Luminous Landscape Forum

Raw & Post Processing, Printing => Digital Image Processing => Topic started by: John R Smith on February 17, 2010, 05:44:56 am

Title: Lab Color for B/W - Why does it work so well?
Post by: John R Smith on February 17, 2010, 05:44:56 am
Good Morning from Cornwall, where after a chilly start the early mist burnt off, and we now have a sunny day with cloudless skies. My question –

I print only B/W photographs, never colour, and after many years of shooting film have now made the transition to a MF digital back for my Hasselblads and have spent the last two months grappling with the complexities of converting a digital colour image to monochrome. This, as you can imagine, has been a steep learning curve. After trying every monochrome strategy I could find out about, and using terrifying quantities of ink and paper in the process, I have come to the conclusion that converting the RGB image to Lab color and extracting the L channel gives me the best result as a basis for the B/W image. But exactly why this should be I don’t know. I can find no technical information on exactly how the Lab L channel is constructed, however perhaps someone here can help.

Why does the L channel from Lab color look different to a straight de-saturation, or a greyscale conversion, or a PS Channel Mixer conversion with the channels set to 33/33/33? Because it does look different – subtly so, perhaps, but nonetheless more punchy and more luminous.

Any technical information would be most welcome.

John
Title: Lab Color for B/W - Why does it work so well?
Post by: Mike Arst on February 17, 2010, 07:22:33 am
I hope you receive informative replies -- I would love to hear more about this. I've recently become interested in trying black and white after a few years of shooting color alone with a digital SLR. Among the reasons I wasn't interested in black and white (though I cut my teeth on b&w printing and once loved to work in the darkroom): I have never had an inkjet printer capable of producing decent black and white prints, and I don't know if I ever will. Printers of that caliber must cost a small fortune. The thought of being able to make only sub-par b&w prints has not been appealing...

Still, it's possible to produce b&w images that display well on the web. Perhaps, I thought, I could at least please myself to that extent.

Recently I ran across a technique that uses the "L" channel -- something worked out, I hear, by a digital-imaging expert who works with John Paul Caponigro. Perhaps it's the same one you've been using. I tried it and was  surprised by how well it worked (I had never been impressed by the channel-mixer approach). My first attempt produced some posterization in the image -- probably because my test image was only an 8-bit TIFF -- but it was clear the technique has a lot of promise.

This was just after I had bought a set of plug-ins called PowerRetouche, two of which perform black and white conversions. It's clear to me that they can do a pretty good job, although it's going to take a while to master them. That aside, the "L" channel approach worked surprisingly well.

(The Photoshop plug-in called Convert to Black And White Pro was widely praised as the best of the lot, but its author stopped developing or supporting it and as far as I know it's no longer possible to get a registered [non-demo] copy.)
Title: Lab Color for B/W - Why does it work so well?
Post by: crames on February 17, 2010, 08:06:10 am
Quote from: John R Smith
... I have come to the conclusion that converting the RGB image to Lab color and extracting the L channel gives me the best result as a basis for the B/W image.
Hi John,

Lab is an implementation of CIELAB, where L is called L* (L-star) and  represents Lightness. Any technical information you find about CIELAB applies.

Lightness is defined as the perceived brightness of a color relative to the brightness of white. L or L* is perceptually uniform, meaning that differences in L correspond to perceived differences in Lightness. So the L channel (accurately) represents the relative brightness of colors in an image.
 
When you say "extracting the L channel", how do you do it exactly? If you are separating the L channel from the a and b channels, either by deleting the a & b channels or by copy/pasting the L channel into an RGB channel, then that L channel no longer represents Lightness, and is interpreted by PS according to the RGB space in effect, or its Gray: setting in Color Settings. The effect of this will in most cases result in a visible change of contrast, depending on the difference between the tone curve of L, which is about gamma=3, and the tone curve of the destination RGB space or gray-scale space. This might explain the difference in punchiness and luminousness you are seeing.

If instead you wanted actually to preserve the L channel as Lightness, then desaturate in Lab mode before converting to the desired RGB or gray-scale space.

Regards,
Cliff
Title: Lab Color for B/W - Why does it work so well?
Post by: John R Smith on February 17, 2010, 08:13:48 am
Mike

I tried many printers, and like you was very underwhelmed with the results in B/W. However, for the last three years I have been printing scanned B/W film to my Epson R2400 and I am very happy indeed. I process the files entirely in 16-bit greyscale, resample to print size and 360 dpi as a final step before USM, and print using the Epson Advanced Black and White mode on Harman FB gloss. The results are indistinguishable from my darkroom prints on the old Ilford Galerie paper, except for a little bit of gloss differential. I know this, because I have scanned 25 year old MF negs for which I already had prints, printed to the same size and compared the outputs very critically.

So I would have thought that any Epson printer which has the ABW mode would do the same for you.

John
Title: Lab Color for B/W - Why does it work so well?
Post by: John R Smith on February 17, 2010, 08:24:15 am
Quote from: crames
When you say "extracting the L channel", how do you do it exactly? If you are separating the L channel from the a and b channels, either by deleting the a & b channels or by copy/pasting the L channel into an RGB channel, then that L channel no longer represents Lightness, and is interpreted by PS according to the RGB space in effect, or its Gray: setting in Color Settings. The effect of this will in most cases result in a visible change of contrast, depending on the difference between the tone curve of L, which is about gamma=3, and the tone curve of the destination RGB space or gray-scale space. This might explain the difference in punchiness and luminousness you are seeing.

Cliff

In PS(7) I convert to Lab from RGB (all 16-bit), select the L-channel from the channels palette, go to Mode > Greyscale, and click OK to "Discard Other Channels?". I can observe no visible difference on screen or in the histogram in the L channel before and after this process.

John
Title: Lab Color for B/W - Why does it work so well?
Post by: crames on February 17, 2010, 08:52:52 am
Quote from: John R Smith
In PS(7) I convert to Lab from RGB (all 16-bit), select the L-channel from the channels palette, go to Mode > Greyscale, and click OK to "Discard Other Channels?". I can observe no visible difference on screen or in the histogram in the L channel before and after this process.
John,

I believe that by selecting the L channel before converting to Grayscale, the L channel is interpreted according to the Gray: setting in Color Settings. In other words, your results depend on whatever the Gray: setting is.

If you were to convert to Grayscale without selecting the L channel (convert while viewing all channels = full-color version), actual Lightness will be preserved. (I'm not saying you should preserve Lightness, just that the results will be different)

To duplicate your results, what is your Gray: setting in Color Settings?

Cliff
Title: Lab Color for B/W - Why does it work so well?
Post by: Mark D Segal on February 17, 2010, 09:21:22 am
There are scads of resources on the internet and in books about converting to B&W and everyone has their favorite techniques ranging from the most simple to the most convoluted. I've been doing this for quite a while with quite a few images and would recommend the following. But for starters, there is nothing particularly complex about what you need to do to get first-class results, so the keep-it-simple philosophy should serve you well.

For medium format digital captures, if Capture 1 can read your raw files, use Capture-1 and convert to B&W non-destructively using the controls offered there. It produces excellent results.

If Capture-1 cannot handle your files but Lightroom/Camera Raw can, use the Grayscale option in the HSL panel (LR) to make a non-destructive well-controlled B&W rendition.

If you wish to work on rendered PSD or TIFF files, use the B&W adjustment layer in Photoshop, as it works very much like its counterpart in LR/ACR.

If you wish to use a third-party plug-in which provides a raft of looks, effects and localized controls over luminosity in B&W, there is nothing better on the market these days than Nik Silver EFEX Pro, which is also non-destructive because it works on its own layer.

Forget converting images to Lab. It makes for more work than necesary, is not non-destructive per se, and compared with contemporary techniques mentioned above has no value-added.

Title: Lab Color for B/W - Why does it work so well?
Post by: John R Smith on February 17, 2010, 09:21:53 am
Cliff

Gray = Gray Gamma 2.2. However, in "Color Management Policies", Gray is Off. So that might make a difference, I will have to try it out.

I cannot de-saturate the file (either RGB or Lab) in 16-bit using PS7. It will only desat in 8-bit.

Mark

Thank you for your input. I use the Hasselblad back, so I have Phocus as the RAW converter. That has a B/W option. I have also used the Channel Mixer in PS Elements 6, and various PS plugins I got off the net. Then I tried using ACR and de-saturating there. I have tried all of these, done gazillions of test prints, and given my particular combination of camera/lenses/desires/software/and printer the best result is (to my eyes, and I have been shooting B/W for fifty years) the Lab 'L' channel. I don't know why, but I know what I like. My interest is how the Lab lightness algorithm works compared to a straight desat.

PS These differences are not usually very visible on-screen (or at least not on my screen), but are on my work prints. Just as in the dark room days . . .

John
Title: Lab Color for B/W - Why does it work so well?
Post by: crames on February 17, 2010, 10:30:30 am
Quote from: John R Smith
...I cannot de-saturate the file (either RGB or Lab) in 16-bit using PS7. It will only desat in 8-bit.
Hmm, PS7 does limit the things you can do in 16 bit, but I don't remember which. Maybe try setting  saturation=0 in Hue/Sat, or fill the a and b channels with zero. But  this will give you something different from what you are currently  satisfied with. I think what you're getting is Lightness interpreted in a gamma 2.2 space, which seems to give a small boost to the mid-tones.

Cliff
Title: Lab Color for B/W - Why does it work so well?
Post by: Mike Arst on February 17, 2010, 02:33:35 pm
John --

The technique about which I received the e-mail is discussed here: http://www.designbyfire.com/?p=17 (http://www.designbyfire.com/?p=17) -- with the discussion starting partway through the page. I wish it were a bit more readable (it's odd when designers make web pages with near-unreadable typography...I wonder if they propose similar book designs to their clients...fortunately, browsers' type-size controls to the rescue).

Interesting to hear that the R2400 is capable of doing such good b&w printing. I have the R1800. Close, but not close enough. I can well imagine that the Harman Gloss is a good paper for this purpose, and your finding those prints indistinguishable from darkroom prints on Galerie is a pretty encouraging recommendation. The Harman is certainly good for color. I would have been happy to use Ilford's similar inkjet-paper offering (at least for color; I found it producing somewhat stronger reds and oranges than the Harman), but it has a heavy 'reverse' curl that makes it unusable in the R1800.

Do you have any of your black and white work displayed on the web?


Quote from: John R Smith
Mike

I tried many printers, and like you was very underwhelmed with the results in B/W. However, for the last three years I have been printing scanned B/W film to my Epson R2400 and I am very happy indeed. I process the files entirely in 16-bit greyscale, resample to print size and 360 dpi as a final step before USM, and print using the Epson Advanced Black and White mode on Harman FB gloss. The results are indistinguishable from my darkroom prints on the old Ilford Galerie paper, except for a little bit of gloss differential. I know this, because I have scanned 25 year old MF negs for which I already had prints, printed to the same size and compared the outputs very critically.

So I would have thought that any Epson printer which has the ABW mode would do the same for you.

John
Title: Lab Color for B/W - Why does it work so well?
Post by: BernardLanguillier on February 17, 2010, 04:24:03 pm
Quote from: Mark D Segal
If you wish to use a third-party plug-in which provides a raft of looks, effects and localized controls over luminosity in B&W, there is nothing better on the market these days than Nik Silver EFEX Pro, which is also non-destructive because it works on its own layer.

I would second that.

The images in the linked page below did undergo various manipulations, but Silver efex was part of the workflow for all of them.

http://www.flickr.com/photos/bernardlangui...57623305594697/ (http://www.flickr.com/photos/bernardlanguillier/sets/72157623305594697/)

As far as print goes, I have had execllent results on my Epson 9900 with the Epson driver B&W mode.

Cheers,
Bernard

Title: Lab Color for B/W - Why does it work so well?
Post by: Mark D Segal on February 17, 2010, 04:43:48 pm
Hi Bernard,

As usual - excellent photographs.

I'm using an Epson 3800 and also get clean, neutral B&W results from the combo of Photoshop with the Epson driver, on Ilford Gold Fibre Silk paper.

Cheers,

Mark
Title: Lab Color for B/W - Why does it work so well?
Post by: John R Smith on February 18, 2010, 03:48:53 am
Quote from: Mike Arst
John --

Interesting to hear that the R2400 is capable of doing such good b&w printing. I have the R1800. Close, but not close enough. I can well imagine that the Harman Gloss is a good paper for this purpose, and your finding those prints indistinguishable from darkroom prints on Galerie is a pretty encouraging recommendation. The Harman is certainly good for color. I would have been happy to use Ilford's similar inkjet-paper offering (at least for color; I found it producing somewhat stronger reds and oranges than the Harman), but it has a heavy 'reverse' curl that makes it unusable in the R1800.

Do you have any of your black and white work displayed on the web?

Mike

The 1800 and the 2400 are virtually identical mechanically. However, they are very different in output. I think you would find that there would be a fairly general agreement that the 1800 is best for colour, and the 2400 is far superior for B/W but not so great for colour work. I don't have a website, or any work on the web, because - this is my hobby, not my job (I do quite a lot of photography for work, but that is now all colour digital), and I do B/W for printing on paper, not to look at on screen. And I'm not that great a photographer, anyhow. Still, I could try this attachment thing and see what happens. Hmm, looks as if I may have screwed something up . . . Oh, no, it's worked. Well, there you go, that's a quite nice fern which I have been tending for years on my window seat. Hasselblad 500 C/M, 120mm S-Planar, CFV-39 back.

John
Title: Lab Color for B/W - Why does it work so well?
Post by: Mike Arst on February 18, 2010, 05:39:25 am
John -- thanks for including this sample. Ah, the legendary smoothness of the Hasselblad digital.

I have not been paying attention to the printer market for quite a while and didn't realize until yesterday that Epson has discontinued both the R1800 and R2400 (at least according to their U.S. web site). I now contemplate the likely decreasing availability of those inks (in local stores). Do I have, in effect, a printer-shaped boat anchor, worth a few dollars on eBay not long from now? I didn't find printers comparable to those two on their site. The "low end" printer now seems to be something in the 3xxx series. Perhaps I just haven't searched enough. But if I'm right...what a depressing development. They had the 1270 in their product line for quite a few years. They appear to have changed their approach to "product life." My interest in trying to print b&w is rekindled. But if Epson is going to release printers with ever-shorter life-cycles (and ink types and ink cartridges specific to each model and orphaned by its demise), I don't know if I dare even buy another one of their products...


Quote from: John R Smith
Mike

The 1800 and the 2400 are virtually identical mechanically. However, they are very different in output. I think you would find that there would be a fairly general agreement that the 1800 is best for colour, and the 2400 is far superior for B/W but not so great for colour work. I don't have a website, or any work on the web, because - this is my hobby, not my job (I do quite a lot of photography for work, but that is now all colour digital), and I do B/W for printing on paper, not to look at on screen. And I'm not that great a photographer, anyhow. Still, I could try this attachment thing and see what happens. Hmm, looks as if I may have screwed something up . . . Oh, no, it's worked. Well, there you go, that's a quite nice fern which I have been tending for years on my window seat. Hasselblad 500 C/M, 120mm S-Planar, CFV-39 back.

John
Title: Lab Color for B/W - Why does it work so well?
Post by: Mark D Segal on February 18, 2010, 09:24:27 am
Quote from: Mike Arst
John -- thanks for including this sample. Ah, the legendary smoothness of the Hasselblad digital.

I have not been paying attention to the printer market for quite a while and didn't realize until yesterday that Epson has discontinued both the R1800 and R2400 (at least according to their U.S. web site). I now contemplate the likely decreasing availability of those inks (in local stores). Do I have, in effect, a printer-shaped boat anchor, worth a few dollars on eBay not long from now? I didn't find printers comparable to those two on their site. The "low end" printer now seems to be something in the 3xxx series. Perhaps I just haven't searched enough. But if I'm right...what a depressing development. They had the 1270 in their product line for quite a few years. They appear to have changed their approach to "product life." My interest in trying to print b&w is rekindled. But if Epson is going to release printers with ever-shorter life-cycles (and ink types and ink cartridges specific to each model and orphaned by its demise), I don't know if I dare even buy another one of their products...

Using North American values for the printers and Epson inks, you may not be aware of it, but an Epson 3880 pays for itself over an Epson 2880 (replacements for the 3800 and 2400) once you've made about 400 A4-sized prints, because the ink is so much cheaper on account of the larger cartridges. Not to speak of the quality improvements in gamut, print-head design and B&W rendering. So this is anything but a depressing development - it's real progress. As for life-cycle, the Epson 3800 had a life-cycle of AT LEAST three years, and for many folks will be longer, because eventhough the 3880 is improved over the 3800, perhaps not enough to justify that upgrade. But an up-grade from a 2400 to a 3880 is DEFINITELY a HIGHLY RECOMMENDED progression for anyone who expects to make more than 400 prints over the life of the printer.
Title: Lab Color for B/W - Why does it work so well?
Post by: MarkIV on February 18, 2010, 12:15:03 pm
Quote from: John R Smith
I have come to the conclusion that converting the RGB image to Lab color and extracting the L channel gives me the best result as a basis for the B/W image. But exactly why this should be I don’t know. I can find no technical information on exactly how the Lab L channel is constructed, however perhaps someone here can help. Any technical information would be most welcome.

John

I really would not come to the same conclusion.  

If you want the most powerful flexibility in B+W's (and options) I would set up an action that copies and pastes the RGB Red, Green, and Blue channels, as well as the LAB L channel all as 4 separate layers (all named and the color version trashed).  Then you can simply click on and off the eyeballs on the layers pallet to see the separate qualities of all 4.  I have not found the L channel to be the best, but every image completely different.  Sometimes it is the Red Channel, sometimes the L, sometimes the Green, sometimes even the Blue...  This is an image specific thing.  Then once you identify the particular qualities you prefer in each you can simply, and easily blend them together with different layer opacities (and you can use the Layer Blend Modes, and the Layer Style "Blend If" sliders) for an almost infinite amount of different interpretations and total control of all tones (kind of like Ansel Adam's zone system but on steroids).  Once you have mastered the opasity blend you prefer, you then can easily finish off by doing additional contrast work, or whatever...
Title: Lab Color for B/W - Why does it work so well?
Post by: PeterAit on February 18, 2010, 01:35:28 pm
Quote from: Mark D Segal
Hi Bernard,

As usual - excellent photographs.

I'm using an Epson 3800 and also get clean, neutral B&W results from the combo of Photoshop with the Epson driver, on Ilford Gold Fibre Silk paper.

Cheers,

Mark

Are you printing a color image using the Epson B&W mode? Or, do you convert the image to B&W first and then print?
Title: Lab Color for B/W - Why does it work so well?
Post by: Mark D Segal on February 18, 2010, 02:35:05 pm
Quote from: PeterAit
Are you printing a color image using the Epson B&W mode? Or, do you convert the image to B&W first and then print?

Hi Peter - first, I just visited your website and you have some excellent work there. Congratulations.

I don't use the ABW driver, because I don't have control over soft-proofing with it, though Eric Chan has produced a viable workaround for that with his ABW profiles. If you haven't done so, you may find it interesting to visit Eric's Epson 3800 page.

I haven't gotten into the ABW driver with Eric's profiles, because I've been very satisfied with the methods I'm using, and posted in post #7 above.
Title: Lab Color for B/W - Why does it work so well?
Post by: PeterAit on February 18, 2010, 04:17:34 pm
Quote from: Mark D Segal
Hi Peter - first, I just visited your website and you have some excellent work there. Congratulations.

I don't use the ABW driver, because I don't have control over soft-proofing with it, though Eric Chan has produced a viable workaround for that with his ABW profiles. If you haven't done so, you may find it interesting to visit Eric's Epson 3800 page.

I haven't gotten into the ABW driver with Eric's profiles, because I've been very satisfied with the methods I'm using, and posted in post #7 above.

Thanks, Mark, for the suggestions and comments.
Title: Lab Color for B/W - Why does it work so well?
Post by: Mike Arst on February 19, 2010, 06:16:37 am
I was wrong earlier when I described a B&W conversion technique as being provided by Caponigro. This is the one provided by Caponigro: http://www.adobe.com/digitalimag/ps_pro_primers.html (http://www.adobe.com/digitalimag/ps_pro_primers.html) -- see the link "Black and White Conversion Tutorial" (PDF file).

The technique involves copying and pasting the individual R, G and B channels into the main document, creating a new layer each time you paste. I've tried it a number of times in Photoshop CS2 and haven't been able to get it to work. With each "paste," the new layer that appears in the document contains the data only for the very first channel that was copied. That is, if I first paste the Red channel, at the point when I've copied and pasted the Blue channel, it's still only the red-channel data that appears in the new layer. The same happens when I copy and paste the green-channel data: again I get only the red-channel data in the new layer.

I've been following the instructions slowly and meticulously -- or so I thought -- but clearly I'm doing something wrong. Can anyone reading this message think what it might be? Or, is it possible there's something missing from those instructions?

The web page contains a Photoshop action that's said to automate the sequence of events described in the tutorial. That isn't quite correct. The action does considerably more than is described in the tutorial. When it is run, the channels when pasted into the main document DO look the way I would expect them to look.

(I realize that Silver Efex Pro is a mere $200. Despite the bargain pricing, I would nevertheless like to find some other workable approach, if possible. To date, Convert to B&W Pro having been discontinued, I have not yet found a decent plug-in for this purpose...)
Title: Lab Color for B/W - Why does it work so well?
Post by: papa v2.0 on February 19, 2010, 07:25:00 am
If you want to work in LAB its fine. Once you have removed AB channels or de-saturated the image (Or what ever way suits you). Keep the image in LAB space and print direct from the LAB file. (image is tagged with LAB profile, either convert to printer profile to preview and print or print direct, using relative colormetric)

Reason is most  profiles  use LAB as the profile connection space. So let the printer profile do the LAB conversion to the printer space and see what you get. Dont go RGB to LAB to RGB and print.

Its the way i would go and it will save you £££££s. This is the method we use to send test targets to the printer to evaluate printer profile performance.

Try printing off a stepwedge.
Title: Lab Color for B/W - Why does it work so well?
Post by: Mark D Segal on February 19, 2010, 08:45:15 am
Quote from: Mike Arst
I was wrong earlier when I described a B&W conversion technique as being provided by Caponigro. This is the one provided by Caponigro: http://www.adobe.com/digitalimag/ps_pro_primers.html (http://www.adobe.com/digitalimag/ps_pro_primers.html) -- see the link "Black and White Conversion Tutorial" (PDF file).

The technique involves copying and pasting the individual R, G and B channels into the main document, creating a new layer each time you paste. I've tried it a number of times in Photoshop CS2 and haven't been able to get it to work. With each "paste," the new layer that appears in the document contains the data only for the very first channel that was copied. That is, if I first paste the Red channel, at the point when I've copied and pasted the Blue channel, it's still only the red-channel data that appears in the new layer. The same happens when I copy and paste the green-channel data: again I get only the red-channel data in the new layer.

I've been following the instructions slowly and meticulously -- or so I thought -- but clearly I'm doing something wrong. Can anyone reading this message think what it might be? Or, is it possible there's something missing from those instructions?

The web page contains a Photoshop action that's said to automate the sequence of events described in the tutorial. That isn't quite correct. The action does considerably more than is described in the tutorial. When it is run, the channels when pasted into the main document DO look the way I would expect them to look.

(I realize that Silver Efex Pro is a mere $200. Despite the bargain pricing, I would nevertheless like to find some other workable approach, if possible. To date, Convert to B&W Pro having been discontinued, I have not yet found a decent plug-in for this purpose...)

Have you exhausted the potential of the B&W panel in Lightroom/ACR and the B&W Adjustment Layer in Photoshop? You may well find that by properly using an up-to-date version of Photoshop you simply don't need plug-ins and convoluted workflows to get great results. There's far too much hype all over the place about making B&W conversions, when most often the easiest and most direct approaches are all that one needs.
Title: Lab Color for B/W - Why does it work so well?
Post by: Mark D Segal on February 19, 2010, 08:49:25 am
Quote from: papa v2.0
Reason is most  profiles  use LAB as the profile connection space. So let the printer profile do the LAB conversion to the printer space and see what you get. Dont go RGB to LAB to RGB and print.

Moat inkjet printers are RGB devices and their drivers are written to expect RGB file numbers in RGB colour space. The printer firmware converts these numbers under the hood to CMYK for printing, because the inks are CMYK inks. I don't recommend interfering with that workflow in general and in particular for the sake of using the "L" channel in L*a*b* to make a B&W print.
Title: Lab Color for B/W - Why does it work so well?
Post by: PeterAit on February 19, 2010, 08:53:51 am
Quote from: Mike Arst
I was wrong earlier when I described a B&W conversion technique as being provided by Caponigro. This is the one provided by Caponigro: http://www.adobe.com/digitalimag/ps_pro_primers.html (http://www.adobe.com/digitalimag/ps_pro_primers.html) -- see the link "Black and White Conversion Tutorial" (PDF file).

The technique involves copying and pasting the individual R, G and B channels into the main document, creating a new layer each time you paste. I've tried it a number of times in Photoshop CS2 and haven't been able to get it to work. With each "paste," the new layer that appears in the document contains the data only for the very first channel that was copied. That is, if I first paste the Red channel, at the point when I've copied and pasted the Blue channel, it's still only the red-channel data that appears in the new layer. The same happens when I copy and paste the green-channel data: again I get only the red-channel data in the new layer.

I've been following the instructions slowly and meticulously -- or so I thought -- but clearly I'm doing something wrong. Can anyone reading this message think what it might be? Or, is it possible there's something missing from those instructions?

The web page contains a Photoshop action that's said to automate the sequence of events described in the tutorial. That isn't quite correct. The action does considerably more than is described in the tutorial. When it is run, the channels when pasted into the main document DO look the way I would expect them to look.

(I realize that Silver Efex Pro is a mere $200. Despite the bargain pricing, I would nevertheless like to find some other workable approach, if possible. To date, Convert to B&W Pro having been discontinued, I have not yet found a decent plug-in for this purpose...)

Do you use LightRoom? Its black and white conversion tools are really quite good.
Title: Lab Color for B/W - Why does it work so well?
Post by: Mark D Segal on February 19, 2010, 09:06:22 am
Quote from: PeterAit
Do you use LightRoom? Its black and white conversion tools are really quite good.

Exactly - and the same tools are in recent versions of Camera Raw and Photoshop.
Title: Lab Color for B/W - Why does it work so well?
Post by: John R Smith on February 19, 2010, 09:27:31 am
All of this has been most interesting, and I do thank everyone for taking the time and trouble to contribute to this debate. Now, you are welcome to correct me if I am wrong, but essentially there seem to be the following options if one wishes to use a digital camera or MF digital back and produce not colour images, but B/W prints.

1) Convert to Grayscale from RGB in Image>Mode>Grayscale. This actually is not a straight desaturation, but is more like 30% R, 60% G, and 10% B (according to the info I have found).

2) Desaturate the RGB image in Image>Adjustments>Desaturate. Or desaturate in ACR or other RAW converter using the saturation slider set to zero. This should produce a file which has exactly equal quantities of RGB.

Both of these strategies produce a file which, to my eyes, is rather flat and lifeless. Others may disagree.

3) Use Channel Mixer in PS to mix varying proportions of the R, G and B channels to a monochrome image. This can be understood in two ways - either as attempting to replicate the effect of using coloured filters on the lens as we used to do when shooting film, or attempting to replicate the non-linear response of B/W film stock, or indeed both at once. Most, if not all, of the other plugins, things in PS or CS4 or whatever are just variations or more sophisticated versions of this basic theme. (Some of them are actually quite good - the FP4 profile in CBW Pro is pretty believable. If you like FP4, of course.)

4) Convert the RGB image to Lab Color in Image>Mode>Lab Color and then extract the L channel. CIE Lab seems to produce something genuinely different which is easily differentiated from the other separation methods when you make a print on good-quality stock. Whether you like it better or not is a matter of taste.

Of course, all the above are just the beginning of the process for a fine quality B/W print. Thereafter must follow all the usual adjustments for levels, local contrast, dodging and burning just as we used to do in the darkroom. Essentially, what I am looking for is the perfect negative as my starting point, except that now it is a positive. Following Ansel's practice, it should be correctly exposed, retain the crucial highlight detail, have excellent tonal separation in the all-important mid-range, and have normal contrast. As he so rightly pointed out, we can fairly easily add contrast, but it is much more difficult to reduce it if the crucial upper-mids have been lost.

John
Title: Lab Color for B/W - Why does it work so well?
Post by: Mark D Segal on February 19, 2010, 10:03:38 am
Quote from: John R Smith
All of this has been most interesting, and I do thank everyone for taking the time and trouble to contribute to this debate. Now, you are welcome to correct me if I am wrong, but essentially there seem to be the following options if one wishes to use a digital camera or MF digital back and produce not colour images, but B/W prints.

1) Convert to Grayscale from RGB in Image>Mode>Grayscale. This actually is not a straight desaturation, but is more like 30% R, 60% G, and 10% B (according to the info I have found).

2) Desaturate the RGB image in Image>Adjustments>Desaturate. Or desaturate in ACR or other RAW converter using the saturation slider set to zero. This should produce a file which has exactly equal quantities of RGB.

Both of these strategies produce a file which, to my eyes, is rather flat and lifeless. Others may disagree.

3) Use Channel Mixer in PS to mix varying proportions of the R, G and B channels to a monochrome image. This can be understood in two ways - either as attempting to replicate the effect of using coloured filters on the lens as we used to do when shooting film, or attempting to replicate the non-linear response of B/W film stock, or indeed both at once. Most, if not all, of the other plugins, things in PS or CS4 or whatever are just variations or more sophisticated versions of this basic theme. (Some of them are actually quite good - the FP4 profile in CBW Pro is pretty believable. If you like FP4, of course.)

4) Convert the RGB image to Lab Color in Image>Mode>Lab Color and then extract the L channel. CIE Lab seems to produce something genuinely different which is easily differentiated from the other separation methods when you make a print on good-quality stock. Whether you like it better or not is a matter of taste.

Of course, all the above are just the beginning of the process for a fine quality B/W print. Thereafter must follow all the usual adjustments for levels, local contrast, dodging and burning just as we used to do in the darkroom. Essentially, what I am looking for is the perfect negative as my starting point, except that now it is a positive. Following Ansel's practice, it should be correctly exposed, retain the crucial highlight detail, have excellent tonal separation in the all-important mid-range, and have normal contrast. As he so rightly pointed out, we can fairly easily add contrast, but it is much more difficult to reduce it if the crucial upper-mids have been lost.

John

Approaches (1) and (2) either destroy a lot of information you should keep or they produce sub-optimal results or both - you can read why elsewhere, but your observation that they're no good is correct; approaches (3) and (4) are more convoluted than necessary to make a very high quality B&W rendition, and if you don't have the application engineering background to know what is "just variations" of what, it's probably not productive to speculate - in any case it's only the results that matter. Maybe it would be a productive suggestion to stop ignoring the more straightforward and highly effective advice being offered to you here, for example in posts 7, 23, 24 and 25 - or is it that you prefer convoluted, dated workflows in order to avoid up-grading your software, or are you using file formats which the latest Capture-1, Lightroom and Photoshop versions can't handle (unlikely)? I think at the very least you should give the newer, more straightforward tools a whirl (free trial demos) before coming to conclusions what's been discussed here. Or have you done that already and found it not to your liking?
Title: Lab Color for B/W - Why does it work so well?
Post by: John R Smith on February 19, 2010, 10:22:52 am
Quote from: Mark D Segal
Maybe it would be a productive suggestion to stop ignoring the more straightforward and highly effective advice being offered to you here, for example in posts 7, 23, 24 and 25 - or is it that you prefer convoluted, dated workflows in order to avoid up-grading your software, or are you using file formats which the latest Capture-1, Lightroom and Photoshop versions can't handle (unlikely)? I think at the very least you should give the newer, more straightforward tools a whirl (free trial demos) before coming to conclusions what's been discussed here. Or have you done that already and found it not to your liking?

Well, Mark, all I was doing above was listing the choices which are available to me. And I did say that you were welcome to correct me if I am wrong. I am not trying to ignore anything, but to be frank, extracting the L channel is hardly "convoluted", really, is it? Two or three mouse clicks, actually. My question at the beginning of this thread was not which B/W strategy is best, simply why (technically) does the L channel look different from a straight desaturation. That was all. I still haven't really had an answer to that.

John
Title: Lab Color for B/W - Why does it work so well?
Post by: Mark D Segal on February 19, 2010, 10:45:27 am
Quote from: John R Smith
Well, Mark, all I was doing above was listing the choices which are available to me. And I did say that you were welcome to correct me if I am wrong. I am not trying to ignore anything, but to be frank, extracting the L channel is hardly "convoluted", really, is it? Two or three mouse clicks, actually. My question at the beginning of this thread was not which B/W strategy is best, simply why (technically) does the L channel look different from a straight desaturation. That was all. I still haven't really had an answer to that.

John
John, I hear you, but converting to L*a*b* and back is destructive (this is a huge old debate I'm not trying to revive and won't respond to - you can find it all on the internet - but it's there and should not be ignored). It is only a few mouse clicks, but it's a few mouse clicks more than you need with more up-to-date software that gives you access to better tools; and unless you keep the original file, make a copy, do the L*a*b* thing on the copy, convert it back to RGB, and then copy this reconverted B&W to RGB onto the original RGB file as a layer, it is non-reversible relative to a workflow which simply keeps your B&W work on a separate Adjustment Layer natively if a rendered PSD or TIFF, or as metadata in a raw file which is easliy reversed or amended. So yes, considering all this, using L*a*b* is convoluted and is inferior from a workflow perspective. I'm not arguing that it can't deliver good results - I am arguing that it's needless and quite likely sub-optimal.

Now, as to why the "L" channel looks different from a deaturated version of all three RGB channels, I don't know. I'm not a software engineer and I don't know the colour space math which would explain this. Superficially though, one would expect them to be different because the colour spaces are constructed differently. I can conjure up in my mind the processes which may give rise to those differences, but that isn't a useful substitute for really knowing the answer. You are right to ask for forum members to answer your original question - if they know how   - that's fair ball as we do tend to get carried-away from the OP's original questions in these discussions.
Title: Lab Color for B/W - Why does it work so well?
Post by: joofa on February 19, 2010, 11:04:38 am
Quote from: John R Smith
.. why (technically) does the L channel look different from a straight desaturation.

One way to obtain typical straight desaturation is to take linear R,G,B and multiply them by some weights (derived with some reference white point in mind), which gives you a single number, the relative luminance. Now desatruation is obtained by replicating this single number in R, G, and B. You can convert it to non-linear data by applying a gamma function, where a typical value would be 2.2, i.e., inverse gamma of 1/2.2=0.45. However, for L in the Lab, you would take that relative luminance value, and using the relative luminance value of reference white you would raise it to the inverse gamma of 0.33; the actual process is slightly more complicated with some multiplicative and subtractive constants. So these inverse gammas of 0.45 (or what ever value was chosen by your software program) and the 0.33 in Lab, (together with those multiplicative/subtractive constants) would make the difference.

Title: Lab Color for B/W - Why does it work so well?
Post by: papa v2.0 on February 19, 2010, 01:11:01 pm
Quote from: Mark D Segal
Moat inkjet printers are RGB devices and their drivers are written to expect RGB file numbers in RGB colour space. The printer firmware converts these numbers under the hood to CMYK for printing, because the inks are CMYK inks. I don't recommend interfering with that workflow in general and in particular for the sake of using the "L" channel in L*a*b* to make a B&W print.


Assuming you are using a profile based work flow the image in RGB say sRGB for arguments sake is tagged with a sRGB profile. to print to the printer the file is converted to printer space via the PCS. The PCS is LAB, (well is for my epson inkjet). so the data will go from sRGB to LAB and then EPSON RGB SPACE  and then internally to cmyk probably gamut mapped from LAB space anyway.

so the input to epson RGB space is via LAB not RGB to RGB.
Title: Lab Color for B/W - Why does it work so well?
Post by: Mark D Segal on February 19, 2010, 01:42:28 pm
Quote from: papa v2.0
Assuming you are using a profile based work flow the image in RGB say sRGB for arguments sake is tagged with a sRGB profile. to print to the printer the file is converted to printer space via the PCS. The PCS is LAB, (well is for my epson inkjet). so the data will go from sRGB to LAB and then EPSON RGB SPACE  and then internally to cmyk probably gamut mapped from LAB space anyway.

so the input to epson RGB space is via LAB not RGB to RGB.

However the data gets handled in the CMS and PCS, the print workflow expects an RGB starting point, and the printer profiles we use in Photoshop are also based on reading RGB input data, regardless of whether the CMS and PCS uses CIE L*a*b* or CIE XYZ as the conversion platform. It is true that you can convert your RGB file to L*a*b* which means flattening your image thereby destroying all further access to your adjustment layers (another reason not to use L*a*b* unless you have a duplicate image) and send it to print, and it will print. I have done this and gotten good results, but I don't know (and therefore don't recommend) how reliable this would be accross all images I would print. If you have thoroughly tested and are unequivocally certain that you can begin the print process from Photoshop with L*a*b* data and the resulting print quality will be systematically identical to starting with RGB data in the usual and most recommended way, good to know.
Title: Lab Color for B/W - Why does it work so well?
Post by: crames on February 20, 2010, 12:51:37 am
Quote from: John R Smith
My question at the beginning of this thread was not which B/W strategy is best, simply why (technically) does the L channel look different from a straight desaturation. That was all. I still haven't really had an answer to that.
The difference is that the L channel in Lab is based on the strict CIELAB definition of perceptual lightness and its calculation accounts for the color space and gamma of an image. The result is that the same gray tone will be assigned to a color no matter what the color space. See www.brucelindbloom.com (http://www.brucelindbloom.com/), "Math", for the RGB-to-XYZ and XYZ-to-Lab equations.

The RGB methods use various approximations that seem to ignore the color space and gamma of the image. The result is that the gray tone assigned to a color will vary depending on the color space the image happens to be in. In many cases there is only a rough relationship to perceived lightness. As an example, the Grayscale command appears to involve mixing the RGB channels as: .30*R + .59*G + .11*B. The same ratio is used even though the RGB values for non-neutral colors are different in different color spaces. The mixing is done without regard to whether the RGB values are gamma compressed or not (in contrast, the mixing in Lab is done in the linear XYZ space.)

The Desaturate command appears to use yet another method, resulting in different and varying tones.

Bottom line, the L channel looks different because it's calculated differently.
Title: Lab Color for B/W - Why does it work so well?
Post by: Mike Arst on February 20, 2010, 03:54:24 am
Quote from: Mark D Segal
Have you exhausted the potential of the B&W panel in Lightroom/ACR and the B&W Adjustment Layer in Photoshop? You may well find that by properly using an up-to-date version of Photoshop you simply don't need plug-ins and convoluted workflows to get great results. There's far too much hype all over the place about making B&W conversions, when most often the easiest and most direct approaches are all that one needs.
I definitely have not exhausted these approaches. In fact I'm behind the curve in terms of Photoshop versions, not having felt any burning need to upgrade from CS2 to CS4 -- until, that is, I began to hear some renewed praise for recent versions of ACR (which I had abandoned some time back as not producing especially good results compared with other RAW converters). I hope it has improved in its rendering of fine image detail. This was a clear superiority that I noticed in Capture One, RawShooter Premium, and even the new version of Bibble. All of these beat ACR in terms of fine image detail. I hope ACR has improved in that regard (Lightroom's 1.x versions, at least, didn't impress me fine-image-detail-wise).

Clearly I'd best give the ACR solution a shot (meaning, give CS4 a shot; the ACR version I have doesn't support my camera's format). I have never been fond of Lightroom. I hear, though, that ACR's development "engine's" and LR's are now "identical" (with ACR not having the targeted-adjustments feature). Could this mean that ACR is also now written in LUA? It's hard to imagine how they could be "identical" otherwise. At any rate, having purchased one set of plug-ins that contains an ostensibly decent b&w converter but which turns out to have some fairly serious bugs -- what a disappointment -- I guess I should stop balking at upgrading to CS4...and give it and ACR's b&w solutions a try. Thanks for your feedback about it.
Title: Lab Color for B/W - Why does it work so well?
Post by: Mike Arst on February 20, 2010, 03:59:05 am
Quote from: PeterAit
Do you use LightRoom? Its black and white conversion tools are really quite good.
I haven't used the most recent versions of Lightroom. I became extremely un-fond of its more bizarre UI "features" and for the most part stopped using it. This of course has nothing to do with recent versions' b&w capabilities, and I will take your word about them. If ACR's b&w capability is comparable, I think I'll start there. Being forced into a D.A.M. solution, especially LR's kind of unpleasant implementation, doesn't appeal to me (unless they have made some major progress in the UI dept.). But b&w does appeal to me. :-) Thanks for the feedback about this.
Title: Lab Color for B/W - Why does it work so well?
Post by: stamper on February 20, 2010, 04:05:33 am
Quote from: Mark D Segal
Exactly - and the same tools are in recent versions of Camera Raw and Photoshop.

When you use the convert mode in Camera raw and you import to Photoshop are you changing the mode from grayscale to RGB?
Title: Lab Color for B/W - Why does it work so well?
Post by: Mark D Segal on February 20, 2010, 09:11:08 am
Quote from: stamper
When you use the convert mode in Camera raw and you import to Photoshop are you changing the mode from grayscale to RGB?
It exports to Photoshop as a three channel RGB image. Try it. You'll see the three channels. Turning off one channel at a time, you'll get the opponent colour of the channel you turned off. But when all three channels are active, you see greyscale. However, you are never stuck with that - in case you want to go back to colour, you can revert to the raw file and flip back to Color and re-render it to Photoshop, or you can have the raw version embedded in Photoshop as a Smart Object, which makes it that much more convenient to flip around between various raw states and Photoshop editing. Note however you can't do pixel-editing on a Smart Object.
Title: Lab Color for B/W - Why does it work so well?
Post by: Mark D Segal on February 20, 2010, 09:25:08 am
Quote from: Mike Arst
I haven't used the most recent versions of Lightroom. I became extremely un-fond of its more bizarre UI "features" and for the most part stopped using it. This of course has nothing to do with recent versions' b&w capabilities, and I will take your word about them. If ACR's b&w capability is comparable, I think I'll start there. Being forced into a D.A.M. solution, especially LR's kind of unpleasant implementation, doesn't appeal to me (unless they have made some major progress in the UI dept.). But b&w does appeal to me. :-) Thanks for the feedback about this.

Mike, I own no stock in Adobe and I have no vested interest in pushing their software. Let me just put it to you this way: a very large number of highly successful photographers are using Lightroom to achieve a high proportion of their total workflow and they are making a fine living from it. If it produced crappy conversions and sub-optimal output they would be using something else. I have processed thousands of images in Lightroom, and the detail I can see in print, on paper, is fine - and it has passed muster with peer reviewers who have sharp eyesight and decades of experience looking at prints. So all these opinions I keep reading about the inferior quality of Adobe raw converters leaves me thoroughly unimpressed. You need to distinguish between pixel-peeping as a hobby in its own right, and real world results which people see on paper and judge with their wallets. Yes, anything can always be better, but that goes for everything. The ACR and LR processing engines are the same; the GUI differs. I like Lightroom's GUI better, but that's not a fundamental. As for the file management, again, a great many professional photographers buy this program especially because of its image management capability - in the hands of people who take the time to learn how to use it. This is a major strength of the program. Once you get accustomed to the fact that it ISN'T a file browser, and you begin to "wear it's shoes" so to speak, you can use and appreciate what it can do. Up to now, it has always been worthwhile up-dating Photoshop and Lightroom to take advantage of the newer features. There is and always will be place for high quality third party plugins to perform discrete operations, but they complement rather than replace the advantage of up-grading the base software to which they relate.
Title: Lab Color for B/W - Why does it work so well?
Post by: joofa on February 20, 2010, 10:25:23 am
Quote from: crames
the Grayscale command appears to involve mixing the RGB channels as: .30*R + .59*G + .11*B. The same ratio is used even though the RGB values for non-neutral colors are different in different color spaces. The mixing is done without regard to whether the RGB values are gamma compressed or not (in contrast, the mixing in Lab is done in the linear XYZ space.)

You are right about using incorrect coefficients, and IIRC, even some SMPTE documents have used "traditional" coefficients in lieu of "correct" coefficients. But, if one does not know the right primaries for a given RGB data, then wouldn't even RGB->XYZ conversion be incorrect before going XYZ->Lab?
Title: Lab Color for B/W - Why does it work so well?
Post by: crames on February 20, 2010, 10:37:17 am
Quote from: joofa
You are right about using incorrect coefficients, and IIRC, even some SMPTE documents have used "traditional" coefficients in lieu of "correct" coefficients. But, if one does not know the right primaries for a given RGB data, then wouldn't even RGB->XYZ conversion be incorrect before going XYZ->Lab?
Yes, but all the information you need to convert from RGB to XYZ is contained in the color profile, or working color space definition. That is what is used when converting from RGB to Lab in PS.
Title: Lab Color for B/W - Why does it work so well?
Post by: Mike Arst on February 20, 2010, 02:18:16 pm
Quote from: Mark D Segal
a very large number of highly successful photographers are using Lightroom to achieve a high proportion of their total workflow and they are making a fine living from it.
I believe it, though the program's popularity by itself hasn't been any draw for me. Usability, user interface, and output have been. The UI has always left something to be desired -- in the beginning, it left quite a lot to be desired.
[blockquote]If it produced crappy conversions and sub-optimal output they would be using something else.[/blockquote]I don't recall anyone's having said it did. My comment about rendition of fine image detail is based not on mere "pixel-peeping" but on responses to prints by non-technical people. They all picked the same (non-ACR-/non-Lightroom-"developed") versions as having crisper detail. The pixel-peeping approach also confirmed this. It's possible to become obsessed by "sharpness" to the point of no longer even seeing an image. Having taken photographs for rather a long time, I'm well aware of the danger. That aside, I also saw what they saw both in the prints and at the "pixel level." But that was a while ago. More recent LR/ACR versions might be much different. (That's hardly a "sub-optimal output" sort of comment, kindly note.)
[blockquote]So all these opinions I keep reading about the inferior quality of Adobe raw converters leaves me thoroughly unimpressed[/blockquote]Dunno who was saying that, and shame on them for trying to impress you with all these opinions. I was talking about one aspect of image quality that was better (in the past) in some other applications.
[blockquote]You need to distinguish between pixel-peeping as a hobby in its own right[/blockquote]I always love to hear "You need to..." -- what follows is invariably earth-shakingly valuable advice about what "I need to". And so it was! :-) Strangely, I actually do understand the difference between pixel-peeping and:
[blockquote]real world results which people see on paper and judge with their wallets.[/blockquote]Turns out, I shoot photographs to please myself, not to sell them.
[blockquote]As for the file management[/blockquote]That's what Photo Mechanic + my own Perl scripts do for me. Whenever PM's authors get the D.A.M. version out the door, I'm sure it will be mighty fine. I can hardly wait -- but I can wait. :)
[blockquote]a great many professional photographers buy this program especially because of its image management capability - in the hands of people who take the time to learn how to use it. This is a major strength of the program.[/blockquote]The D.A.M. feature isn't a major strength for someone who doesn't need it, and I found that aspect of the UI fairly unpleasant. YMMV. It's the RAW conversion I'm after. From the sound of it, these days for the B&W conversions ACR could be just as good a candidate. (At one time, it wasn't.)
Title: Lab Color for B/W - Why does it work so well?
Post by: Mark D Segal on February 20, 2010, 02:32:02 pm
Mike - we're in the same boat in terms of why we make photographs, but I do have my ears and eyes tuned to what is happening in the professional marketplace, what the pros are doing, etc. But no matter, what's good for some is not necessarily what's good for all.

In some of my remarks you picked up, I wasn't necessarily aiming at you, but more at the tenor of some other comments in this thread and other closely related ones - this is not the first and won't be the last of these discussions.

I think interface preference is very much a personal thing. I happen to like how Lightroom's GUI is organized a lot. I find it very logical and convenient, and it has some really cool time-saving features. As for how it compares with ACR as a converter - under the hood - same engine, same thing - if you are using comprable versions.

I too mainly use this program for image editing and conversion, and my requirements for on-the-fly asset management are not so large as to find this capability indispensable, but I have seen how pros with very large catalogues pull the images they need so easily and quickly using LR, that it is rather compelling.
Title: Lab Color for B/W - Why does it work so well?
Post by: john beardsworth on February 20, 2010, 04:15:08 pm
Mike

As well as the supposed quality of the conversion, you also need to consider the importance of deciding between alternative black and white conversions, something that hasn't changed since people first started using coloured filters and film.

The Lab method might produce a pleasing, neutral rendition, in many cases. But it offers little scope for creative choice - ie do you want skin tones to appear soft or harsh, do you want clouds to stand out more against the sky, do you want to show the viewer that a green area differs from a neighbouring red region that has the same luminosity? And the Lab method certainly offers no ability to convert part of an image differently from the rest.

Where Lightroom and more modern versions of Photoshop stand out is in making it easy to make such creative decisions. While Lightroom presets can inspire a brain dead recipe-driven approach, in creative hands they can mimic various conversion mixes and mean one just rolls the mouse over them to assess the alternative b&w renditions.

In my view the best feature is the targeted adjustment tool which lets you drag over areas of the image and lighten or darken their greyscale rendition. So you're looking at the image and how blocks of colour are rendering in greyscale tones - thinking in terms of composition and interpretation rather than the pixel peeper's paradise of whether one method is supposedly "better" than another. You also have this with the new black and white adjustment layer in Photoshop CS3.

John
Title: Lab Color for B/W - Why does it work so well?
Post by: MarkIV on February 20, 2010, 05:24:52 pm
Although the Action might be a little complicated for beginner users of PS, once it is set up, working with great flexibility, options and control on B+W's is a cinch (as apposed to convoluted). Setting up the action should take maybe 5 minutes.  Here is a simple but powerful formula:

Get the color raw image to look great in color, in ACR with your preferred white balance (it can be relatively saturated).

Once the image is brought into PS (in 16 bit) start recording the Action (and maybe assign it an F-Key) by going to Windows/Actions/New Action.

The B+W Action:

With your RGB image open in PS, go to Channels palette, Copy the Blue channel (select all, CTRL A, copy, CTRL C).
Click on the composite (RGB) channel (the top one) there before going back to your layers pallet.
Open a New Document (once you do this just click "OK" and it will be the right size and color space) and then paste (CTRL V) the Blue channel there, name it in the layers palette "Blue" (by double clicking on the name) and then flatten the layer (Layer/Flatten) to get rid of the extra canvas underneath the layer.
Go back to the original RGB image and do the same thing for the Green Channel (select all, then copy the green channel).
Go back to the New Document and paste the Green Chanel into the document on top of the Blue one, name it and don't flatten.
Go back to the original RGB image and do the same thing for the Red Chanel (copy the Red Chanel).
Go back to the New Document and paste the Red Chanel into the document on top of the Green one, name it, don't flatten.
Go back to the Original, and convert the color space to LAB (Image/Mode/LAB).
Click on the L-Chanel (in the Channels Pallet) and select all, and copy.
Go back to the New Document and paste the LAB, L -Chanel into the document on top of the Red one, name it and don't flatten. (yes the L Chanel will convert to your preferred RGB space with no quality loss or significant noticeable change).  
Name the top Chanel L.

Stop recording the Action.

You are done.

Now you have the R, the G, the B, and the L (and potentially anything else you want) sitting there with the press of one simple button as Layers (and all the power that goes along with that).

Now all you have to do is enjoy looking at the different qualities of each channel (clicking on and off each eyeballs in the Layers pallet) figure out an opacity mix you like the most (or even just work with one).  As previously mentioned, you now can also use layer Blend Modes, and the Layer Style "Blend If" sliders for unprecedented power, control and options for your B+W's (also blending of layers by standard erasing, or making selections and feathering and deleting or graduated erasing with a mask and gradient...).  Once you get the B+W image just the way you like it most (by working simply or more powerfully) Flatten the image and then do additional contrast work (if you want, both globally and locally).  

If you keep a color layer in the mix (at the bottom of your layer stack) you could also add b&w adjustment layers to the mix or even a channel mixer layer if you so desire.

There are ways to make this even more powerful, but for most people this is plenty and can take their B+W's into a new stratospheric realm.

BTW, this is the general technique I teach my B+W PS students, bypassing the basic Channel mixer and such.  So far it has worked wonders for them.
Title: Lab Color for B/W - Why does it work so well?
Post by: Mike Arst on February 20, 2010, 05:32:54 pm
Quote from: johnbeardy
As well as the supposed quality of the conversion, you also need to consider the importance of deciding between alternative black and white conversions, something that hasn't changed since people first started using coloured filters and film.
I remember that kind of decision. As with the time I decided to try my hand at black and white "subtlety" by buying a color enlarger (found it used, fortunately) that allowed you to dial in filtration via gel filters mounted in front of the light sources. Oh, what science I was going to do with it. The heat was oppressive. Ok, so use a neg carrier with glass. The dust was oppressive. :-) And when I realized what a fortune I'd be spending in gels -- given the intensity of those halogen bulbs, the dyes couldn't possibly remain stable for long -- I gave that up and went back to the cold-light head.

But the real joy came from the hard work of burning and dodging, not to mention the choice of paper and developer and toner. One challenge with the digital work is that I came to enjoy the darkroom experience (the smells and the carcinogens aside) and of course staring into the computer screen isn't at all like that. Perhaps I should build a darkroom (no plumbing required, of course), put the printer in there with a wireless setup, and then go in there and turn on a safelight as the print emerges from the inkjet printer. How Zen it will be. :)

Quote
The Lab method might produce a pleasing, neutral rendition, in many cases.
I have noticed this in the Greg Gorman technique (which I mis-identified, earlier, as having been recommended by John Paul Caponigro -- whose technique still isn't producing on-screen for me what it's claimed to do in the instructions...color me "baffled"). The LAB approach is producing a fairly neutral-looking result. Yet, it's less "greyish" than the Channel Mixer solutions I've also read about. The addition of a Levels adjustment has been useful as well.

I did have some success altering the look of skin-tones with the Gorman technique. You're right, though, about the difficulty of depicting that "a green area differ from a neighbouring red region that has the same luminosity." Yes, that's going to be difficult or even impossible using such a technique. The Caponigro technique, using multiple channels pasted into the original image as layers, would probably provide this ability...well, if I could get it to work.

There is another alternative at hand at least vaguely analogous to the LR/PS approaches recommended in this thread. For better or worse (sometimes I think "worse") I bought the 5.0 version of Bibble. Many problems yet, though the conversions aren't all bad and its rendition of fine image detail is very good -- comparable, IMO, to Capture One's. There is a not-terribly-expensive plug-in for it that provides many "film" choices and even tries to mimic the effects of varying film and paper development (number of minutes in Absurditol at such-and-such at 'x' degrees, that kind of thing). It does seem to work pretty well. And I believe Bibble can edit TIFF files. This might be worth a try...

Regarding your description of LR's targeted-adjustment feature (which as I recall is not present in ACR): in the LR version I now have, that makes a global change in the image and doesn't restrict it to the area immediately near the mouse position. But have they added selection tools for this purpose?

Thanks,
Mike
Title: Lab Color for B/W - Why does it work so well?
Post by: john beardsworth on February 20, 2010, 05:35:47 pm
And why would you want to bypass the channel mixer (or the new b&w adjustment layer)? I've never understood why anyone likes this channels-to-layers method. Any of the blend-if or blend mode tricks are not unprecedented but can be accomplished equally well with adjustment layers, you can't use the method with a smart object workflow that retains the editability of the raw data, it complicates any retouching, and it wipes your metadata.
Title: Lab Color for B/W - Why does it work so well?
Post by: john beardsworth on February 20, 2010, 05:46:35 pm
Quote from: Mike Arst
Regarding your description of LR's targeted-adjustment feature (which as I recall is not present in ACR): in the LR version I now have, that makes a global change in the image and doesn't restrict it to the area immediately near the mouse position. But have they added selection tools for this purpose?
It affects the global conversion recipe, but does so on the basis of sampling local areas. So dragging upwards on a face would lighten all reds in the image. But that's not necessarily a weakness -  dragging means keeping your eyes on the image and considering its appearance. The TAT is also in Photoshop, so you can use multiple b&w adjustment layers to limit a conversion to selected regions.

John
Title: Lab Color for B/W - Why does it work so well?
Post by: MarkIV on February 20, 2010, 05:47:13 pm
Quote from: johnbeardy
And why would you want to bypass the channel mixer (or the new b&w adjustment layer)? I've never understood why anyone likes this channels-to-layers method. Any of the blend-if or blend mode tricks are not unprecedented but can be accomplished equally well with adjustment layers, you can't use the method with a smart object workflow that retains the editability of the raw data, it complicates any retouching, and it wipes your metadata.

I was editing my post as you posted this.

My edit:

"If you keep a color layer in the mix (at the bottom of your layer stack) you could also add b&w adjustment layers to the mix or even a channel mixer layer if you so desire."
Title: Lab Color for B/W - Why does it work so well?
Post by: john beardsworth on February 20, 2010, 05:51:03 pm
Quote from: MarkIV
I was editing my post as you posted this.

My edit:

"If you keep a color layer in the mix (at the bottom) you can also add b&w adjustment layers to the mix or even a channel mixer layer."

Agreed! Using adjustment layers also has the advantage that it's nice and easy to produce a colour print some time in the future.

John
Title: Lab Color for B/W - Why does it work so well?
Post by: Mark D Segal on February 20, 2010, 05:55:26 pm
Quote from: MarkIV
Although the Action might be a little complicated for beginner users of PS, once it is set up, working with great flexibility, options and control on B+W's is a cinch (as apposed to convoluted). Setting up the action should take maybe 5 minutes.  Here is a simple but powerful formula:

Get the color raw image to look great in color, in ACR with your preferred white balance (it can be relatively saturated).

Once the image is brought into PS (in 16 bit) start recording the Action (and maybe assign it an F-Key) by going to Windows/Actions/New Action.

The B+W Action:

With your RGB image open in PS, go to Channels palette, Copy the Blue channel (select all, CTRL A, copy, CTRL C).
Click on the composite (RGB) channel (the top one) there before going back to your layers pallet.
Open a New Document (once you do this just click "OK" and it will be the right size and color space) and then paste (CTRL V) the Blue channel there, name it in the layers palette "Blue" (by double clicking on the name) and then flatten the layer (Layer/Flatten) to get rid of the extra canvas underneath the layer.
Go back to the original RGB image and do the same thing for the Green Channel (select all, then copy the green channel).
Go back to the New Document and paste the Green Chanel into the document on top of the Blue one, name it and don't flatten.
Go back to the original RGB image and do the same thing for the Red Chanel (copy the Red Chanel).
Go back to the New Document and paste the Red Chanel into the document on top of the Green one, name it, don't flatten.
Go back to the Original, and convert the color space to LAB (Image/Mode/LAB).
Click on the L-Chanel (in the Channels Pallet) and select all, and copy.
Go back to the New Document and paste the LAB, L -Chanel into the document on top of the Red one, name it and don't flatten. (yes the L Chanel will convert to your preferred RGB space with no quality loss or significant noticeable change).  
Name the top Chanel L.

Stop recording the Action.

You are done.

Now you have the R, the G, the B, and the L (and potentially anything else you want) sitting there with the press of one simple button as Layers (and all the power that goes along with that).

Now all you have to do is enjoy looking at the different qualities of each channel (clicking on and off each eyeballs in the Layers pallet) figure out an opacity mix you like the most (or even just work with one).  As previously mentioned, you now can also use layer Blend Modes, and the Layer Style "Blend If" sliders for unprecedented power, control and options for your B+W's (also blending of layers by standard erasing, or making selections and feathering and deleting or graduated erasing with a mask and gradient...).  Once you get the B+W image just the way you like it most (by working simply or more powerfully) Flatten the image and then do additional contrast work (if you want, both globally and locally).  

If you keep a color layer in the mix (at the bottom of your layer stack) you could also add b&w adjustment layers to the mix or even a channel mixer layer if you so desire.

There are ways to make this even more powerful, but for most people this is plenty and can take their B+W's into a new stratospheric realm.

BTW, this is the general technique I teach my B+W PS students, bypassing the basic Channel mixer and such.  So far it has worked wonders for them.

Setting aside the hype about "stratospheric realm", have you ever actually compared the result you get using this so-called "not-convoluted" procedure with intelligent use of the Greyscale mode in Lightroom/ACR or the B&W adjustment Layer in PS, combined with curves etc. if needed?
Title: Lab Color for B/W - Why does it work so well?
Post by: Mike Arst on February 20, 2010, 08:14:56 pm
Quote from: MarkIV
Now all you have to do is enjoy looking at the different qualities of each channel (clicking on and off each eyeballs in the Layers pallet) figure out an opacity mix you like the most (or even just work with one).

Thanks for posting these steps. The action was easy enough to record. I did add one step in which the history state of the original document is tweaked to undo the effect of converting to LAB mode.

The aftermath seems a bit limiting in this respect (or else I'm the limited one): if opacity of the uppermost layer (Lightness, unless you've moved them) remains 100%, clicking the others on and off to toggle their visibility has no effect at all. This means either setting the uppermost layer to less than 100%, or moving one of the others to the top. In which case, its characteristics are the only visible ones unless its opacity is reduced below 100% -- and again clicking the others on and off (or changing their blending mode) has no effect. Finally, if the first layer copied (Blue) is made the active one and its opacity is reduced, this introduces obvious transparency into the file... all of this leaves me wondering if I might have missed something obvious in the procedure. Why would clicking individual layers off and on, wherever they might be in the stack, not make their effects immediately invisible/visible? How to transfer transparency "out" of that Blue layer?
Title: Lab Color for B/W - Why does it work so well?
Post by: Schewe on February 21, 2010, 12:35:58 am
Quote from: Mike Arst
Regarding your description of LR's targeted-adjustment feature (which as I recall is not present in ACR)

Wrong...Camera Raw got the TAT in version 5.2.

Title: Lab Color for B/W - Why does it work so well?
Post by: Mike Arst on February 21, 2010, 03:37:53 am
Quote from: Schewe
Wrong...Camera Raw got the TAT in version 5.2.
Well...better news yet, then.
Title: Lab Color for B/W - Why does it work so well?
Post by: stamper on February 21, 2010, 03:59:16 am
Quote from: Mark D Segal
It exports to Photoshop as a three channel RGB image. Try it. You'll see the three channels. Turning off one channel at a time, you'll get the opponent colour of the channel you turned off. But when all three channels are active, you see greyscale. However, you are never stuck with that - in case you want to go back to colour, you can revert to the raw file and flip back to Color and re-render it to Photoshop, or you can have the raw version embedded in Photoshop as a Smart Object, which makes it that much more convenient to flip around between various raw states and Photoshop editing. Note however you can't do pixel-editing on a Smart Object.

In CS3 when I tick the HSL/Grayscale box and import to Photoshop it appears as a one channel layer. I then have to Image /mode /RGB to get a three channel version and when I inspect the three channels there is little difference. What version of Photoshop are you using?
Title: Lab Color for B/W - Why does it work so well?
Post by: Mark D Segal on February 21, 2010, 09:08:06 am
Quote from: stamper
In CS3 when I tick the HSL/Grayscale box and import to Photoshop it appears as a one channel layer. I then have to Image /mode /RGB to get a three channel version and when I inspect the three channels there is little difference. What version of Photoshop are you using?

CS4 and I export from LR 2.6 as a 16-bit ProPhoto PSD file.
Title: Lab Color for B/W - Why does it work so well?
Post by: JeffKohn on February 21, 2010, 12:07:16 pm
LR may export B/W images as RGB, but if you convert them in ACR using the Grayscale option, you'll get a grayscale image (not RGB), unless you also use the toning controls.
Title: Lab Color for B/W - Why does it work so well?
Post by: MarkIV on February 21, 2010, 09:30:04 pm
Quote from: Mark D Segal
Setting aside the hype about "stratospheric realm", have you ever actually compared the result you get using this so-called "not-convoluted" procedure with intelligent use of the Greyscale mode in Lightroom/ACR or the B&W adjustment Layer in PS, combined with curves etc. if needed?

I see no hype.  The sheer flexibility and possibilities are nothing short of potentially stratospheric when competent and creative use of all the aforementioned tools are employed.

Yes, I have compared the techniques.  I enjoy testing.  

It is my opinion that the technique I mention above is much more flexible and powerful (and can even allow for greyscale and ACR/Lightroom layers to be in the mix if you want them added).  It may be convoluted for some, especially potentially those without basic PS skills, but at the same time it can be approached simply without all the power harnessed.  I teach basic to advanced PS users this technique and even the basic users have done very well with it.  

I'm not saying this is the only way to make a B+W, just one of the more flexible/powerful ways I have found.

 

Quote from: Mike Arst
Thanks for posting these steps. The action was easy enough to record. I did add one step in which the history state of the original document is tweaked to undo the effect of converting to LAB mode.

The aftermath seems a bit limiting in this respect (or else I'm the limited one): if opacity of the uppermost layer (Lightness, unless you've moved them) remains 100%, clicking the others on and off to toggle their visibility has no effect at all. This means either setting the uppermost layer to less than 100%, or moving one of the others to the top. In which case, its characteristics are the only visible ones unless its opacity is reduced below 100% -- and again clicking the others on and off (or changing their blending mode) has no effect. Finally, if the first layer copied (Blue) is made the active one and its opacity is reduced, this introduces obvious transparency into the file... all of this leaves me wondering if I might have missed something obvious in the procedure. Why would clicking individual layers off and on, wherever they might be in the stack, not make their effects immediately invisible/visible? How to transfer transparency "out" of that Blue layer?

Sorry if I am having a hard time tracking with the question(s).

Hopefully this helps. Just leave the eyeball on that you want to see.  Turn them all off then toggle each one on and off to see the differences.  You can also move them (the layers) around in the stack to compare or blend.  If you like the L and the green for example, then move the green underneath the L and turn off all the other eyeballs.  Then clicking on the L channel you can mix the layers to whatever opacity you like.  That is a simple way of doing it.  The real power, for myself, comes in when incorporating things like the Layer Styles "Blend If" sliders.  Maybe I like the highlights of one and the shadows of another.  The blend if's allow for that type of blending, among many other things.
Title: Lab Color for B/W - Why does it work so well?
Post by: Schewe on February 21, 2010, 10:18:30 pm
Quote from: Mike Arst
Well...better news yet, then.

If you are still using Camera Raw 3.x in Photoshop CS2, then I suggest you step into the new millennium...Camera Raw made a HUGE change with version 4.1 in Photoshop CS3 an moved even further to the head of class with Camera Raw 5.x in Photoshop CS4. Now, Lightroom 3 beta is even FURTHER removed from your experience...

When Photoshop CS5 (Lightroom 3/Camera Raw 6) ships, you'll prolly want to jump on it to advance to at least current tech. Also note that CS2 will be the OLDEST version that can update to CS5 (Adobe has adopted a 3 version back upgrade policy).


At this point, doing either ACR/LR B&W conversions and printing with recent printers (such as 2880/3880/x900 series) means really great Digital B&W prints have been around for a few years now...
Title: Lab Color for B/W - Why does it work so well?
Post by: stamper on February 22, 2010, 04:07:16 am
Quote from: JeffKohn
LR may export B/W images as RGB, but if you convert them in ACR using the Grayscale option, you'll get a grayscale image (not RGB), unless you also use the toning controls.

I tried as you suggested. Used the toning controls. Also exported as a smart object and not as a smart object. Still a one channel gray background layer. Could it be the settings in Photoshop?
Title: Lab Color for B/W - Why does it work so well?
Post by: DeanSonneborn on February 23, 2010, 12:32:27 am
Sometimes when I use the 3 or 4 layer method and I make adjustments I don't see any differences or changes. I use the split to layer action that I download from adobe so I know the basic action is performed correctly. Then maybe I can adjust 1 layer and then to others don't seem to have any additional effect. I've also used the gorman technique but I usually need to adjust the midtones to a level that I like. Here's and interesting observation: sometimes I use both techniques and have both images on the screen and I can use either technique to replicate the look of the other technique. I'm beginning to think that difference techniques can lead to a similar outcome, so perhaps the specific technique is less important than I originally thought since I seem to be able to get the image to where I want it. I do wish I understood why, sometimes, adjusting the layers in the 3 layer technique do not seem to result in any visible  changes in the image
Title: Lab Color for B/W - Why does it work so well?
Post by: john beardsworth on February 23, 2010, 04:25:37 am
Quote from: DeanSonneborn
...I'm beginning to think that difference techniques can lead to a similar outcome, so perhaps the specific technique is less important than I originally thought since I seem to be able to get the image to where I want it.
That's kinda what I was saying. Focussing too much on the technique takes away from your interpretation of the subject, or your ability to separate colours into distinct tones of grey. However, if you use Lightroom or Photoshop's targeted adjustment tools, you are keeping your eyes on the picture's appearance.

As well as taking your eyes off the picture, the 3 layer technique is pointless when you can achieve the same outcome by using adjustment layers (the B&W adjustment layer if you have CS3/4 and the channel mixer for earlier versions). And if you read that Gorman article quickly, it's more about toning than about the art of black and white and its Lab method is merely one whose conversion looks OK with skin tones. The results are always pretty neutral and the method gives little scope for interpretation - hence your need to do more work afterwards changing the midtones. With the more modern techniques, you can vary the conversion recipe to produce tonal separation (make greens look different from reds etc) or to interpret the image (eg make clouds stand out more or less).

John
Title: Lab Color for B/W - Why does it work so well?
Post by: Mark D Segal on February 23, 2010, 07:04:40 am
If you make changes to Adjustment Layers regardless of where they are in the layer stack, you will see the changes in the image. If you make changes to pixel-based layers, the upper-most layer predominates.

Your observation that different techniques can produce very similar results is correct, and to the extent that's true it argues for using the least convoluted, most efficient approach available for achieving the B&W tonality you like.
Title: Lab Color for B/W - Why does it work so well?
Post by: Mark D Segal on February 23, 2010, 07:10:15 am
Quote from: johnbeardy
That's kinda what I was saying. Focussing too much on the technique takes away from your interpretation of the subject, or your ability to separate colours into distinct tones of grey. However, if you use Lightroom or Photoshop's targeted adjustment tools, you are keeping your eyes on the picture's appearance.

As well as taking your eyes off the picture, the 3 layer technique is pointless when you can achieve the same outcome by using adjustment layers (the B&W adjustment layer if you have CS3/4 and the channel mixer for earlier versions). And if you read that Gorman article quickly, it's more about toning than about the art of black and white and its Lab method is merely one whose conversion looks OK with skin tones. The results are always pretty neutral and the method gives little scope for interpretation - hence your need to do more work afterwards changing the midtones. With the more modern techniques, you can vary the conversion recipe to produce tonal separation (make greens look different from reds etc) or to interpret the image (eg make clouds stand out more or less).

John

I agree, and not only for the convenience of instant feedback re appearance,  but also of course those targeted adjustment tools really do a very good job.

As well, when you combine the B&W Adjustment Layer (or the Greyscale panel in LR/ACR) with Curves and Layer masking, one can get an infinity of effects. And if one wants even more easy options and localized control, and does a lot of B&W work, Nik SIlver Efex Pro (used within Photoshop as a plugin) is highly recommended. Conversion to L*a*b* is not necessary to produce good B&W skin tones.
Title: Lab Color for B/W - Why does it work so well?
Post by: DeanSonneborn on February 25, 2010, 09:59:22 pm
t seems that if I set the opacity of 1 one the layers to 100%, that then making any adjustment above that 100% layer, seems not to have any effect.

Quote from: Mark D Segal
If you make changes to Adjustment Layers regardless of where they are in the layer stack, you will see the changes in the image. If you make changes to pixel-based layers, the upper-most layer predominates.

Your observation that different techniques can produce very similar results is correct, and to the extent that's true it argues for using the least convoluted, most efficient approach available for achieving the B&W tonality you like.
Title: Lab Color for B/W - Why does it work so well?
Post by: Mark D Segal on February 25, 2010, 10:07:06 pm
Quote from: DeanSonneborn
t seems that if I set the opacity of 1 one the layers to 100%, that then making any adjustment above that 100% layer, seems not to have any effect.

If you are trying to say that by setting an underlying layer to 100% opacity, any adjustments to the layer sitting above it have no effect, I don't see how this is possible. I can't replicate it. Or do you mean something else? And are you talking about layers containing pixels, or adjustment layers?
Title: Lab Color for B/W - Why does it work so well?
Post by: DeanSonneborn on February 25, 2010, 11:40:18 pm
I usually set my layers as red on the bottom, green in the middle, and blue on the top. If I set the opacity of the red layer to 100% then try to adjust the green layer opacity I don't see any changes to the over all image.

Quote from: Mark D Segal
If you are trying to say that by setting an underlying layer to 100% opacity, any adjustments to the layer sitting above it have no effect, I don't see how this is possible. I can't replicate it. Or do you mean something else? And are you talking about layers containing pixels, or adjustment layers?
Title: Lab Color for B/W - Why does it work so well?
Post by: john beardsworth on February 26, 2010, 03:05:45 am
Really, as shown by your confusion here, the layers method is a contorted way of working and produces no better results than more modern methods. You'd be better off using on or more adjustment layers.

John
Title: Lab Color for B/W - Why does it work so well?
Post by: Mark D Segal on February 26, 2010, 08:21:53 am
Quote from: DeanSonneborn
I usually set my layers as red on the bottom, green in the middle, and blue on the top. If I set the opacity of the red layer to 100% then try to adjust the green layer opacity I don't see any changes to the over all image.

Oh - I didn't realize you were speaking of the contorted method of getting to B&W by converting channels to layers; I thought you were talking about the normal way of using Photoshop. If it's in the context of the former, good as its proponents say it is and I won't argue, I have no idea why it's not working because it isn't a procedure to which I would commit time.
Title: Lab Color for B/W - Why does it work so well?
Post by: Mark D Segal on February 26, 2010, 08:22:27 am
Quote from: johnbeardy
Really, as shown by your confusion here, the layers method is a contorted way of working and produces no better results than more modern methods. You'd be better off using on or more adjustment layers.

John

Indeed.
Title: Lab Color for B/W - Why does it work so well?
Post by: DeanSonneborn on February 26, 2010, 09:05:08 am
I had heard that the layer technique was "the best" and so I thought I would give it a try but, as you all can see, it seems to be more trouble than it is worth. I too may return to LR B&W and local adjustment tools.

Quote from: Mark D Segal
Indeed.
Title: Lab Color for B/W - Why does it work so well?
Post by: Schewe on February 26, 2010, 12:43:31 pm
Quote from: johnbeardy
Really, as shown by your confusion here, the layers method is a contorted way of working and produces no better results than more modern methods.


Actually, the channels>layers can produce results that are near impossible to reproduce using adjustment layers...

See, if you start with a color image and use the B&W adjustment, Desaturate, Channel Mixer, etc. you get a global conversion to B&W.

There is no easy way to have local control how the conversion will be handled...you can't use layer masks because, well if you mask part of the adjustment layer, the reveal will be back to the color image and trying to place yet another adjustment layer over it becomes problematic...

In terms of B&W conversion in the raw processor, same global deal.

Where the channel>layer is superior is that you can literally paint in a custom B&W conversion area by area and use masks to control what layer are visible. It's pretty easy to do an action that will do the base conversion for you and add hide all layer masks so all you need to do is choose the layer and paint it in via the mask.

I won't claim it's "the best" way...I often do B&W conversions directly in Camera Raw or Lightroom (usually Lightroom where I can make a virtual copy and keep the color & B&W separate). But if you need precise control over different areas in a B&W conversion then the channel>layer is a good solution. Of course, one does have to know how to do it...
Title: Lab Color for B/W - Why does it work so well?
Post by: Mark D Segal on February 26, 2010, 12:52:44 pm
Quote from: Schewe
But if you need precise control over different areas in a B&W conversion then the channel>layer is a good solution. Of course, one does have to know how to do it...

Jeff, refined localized control is also very much achievable using Nik Silver Efex, and it's a helluva lot easier than replicating this kind of functionality directly in PS. Of course it's another 160 bucks, but for those who may be doing a lot of this stuff, most likely worth its cost in time saved and additional features/functionality. I've been playing with it on-and-off and like it.
Title: Lab Color for B/W - Why does it work so well?
Post by: Jeremy Roussak on February 26, 2010, 01:02:03 pm
Quote from: DeanSonneborn
I usually set my layers as red on the bottom, green in the middle, and blue on the top. If I set the opacity of the red layer to 100% then try to adjust the green layer opacity I don't see any changes to the over all image.
Well, I'm no PS wizard, but I believe that that's what "100% opacity" means. The red layer is completely (100%) opaque, so of course you don't see any difference if you fiddle with layers underneath. What did you expect?

Jeremy
Title: Lab Color for B/W - Why does it work so well?
Post by: DeanSonneborn on February 26, 2010, 06:12:08 pm
I was not quite sure what to expect so I thought I would "test" and see. Nothing wrong with that and your right 100% means 100%, end of adjustment. See, now I know.


Quote from: kikashi
Well, I'm no PS wizard, but I believe that that's what "100% opacity" means. The red layer is completely (100%) opaque, so of course you don't see any difference if you fiddle with layers underneath. What did you expect?

Jeremy
Title: Lab Color for B/W - Why does it work so well?
Post by: Schewe on February 26, 2010, 09:43:09 pm
Quote from: Mark D Segal
Jeff, refined localized control is also very much achievable using Nik Silver Efex

So, you have the full capability of using Color Range and/or other Photoshop selection techniques such as paths or calculations to create your local selection of color>B&W conversions? You do if you use channels as layers (and have the color image open in order to make color based selections).

Really, haven't you ever seen me demo the channels to layers technique? If you want total, absolute control (without having to resort to actual tone changes) it's the most powerful method of controlling the result...
Title: Lab Color for B/W - Why does it work so well?
Post by: Mark D Segal on February 26, 2010, 09:46:57 pm
No I haven't seen your demo. Can you point me to it?

But have you tried Silver Efex Pro's U-point selection technology along with their various effects filters?
Title: Lab Color for B/W - Why does it work so well?
Post by: Schewe on February 26, 2010, 09:56:43 pm
Quote from: Mark D Segal
No I haven't seen your demo. Can you point me to it?

Uh well, it's old but try THIS LINK (http://www.pixelgenius.com/tips/schewe-color-bw.pdf) (800KB PDF)

Quote from: Mark D Segal
But have you tried Silver Efex Pro's U-point selection technology along with their various effects filters?

No, sorry, I don't do NIK–for obvious reasons if you think about it...

:~)

But I'm pretty darn sure the channels>layers is still more powerful and flexible (and easy if you record an action to create your layers and layer masks).
Title: Lab Color for B/W - Why does it work so well?
Post by: stamper on February 27, 2010, 04:17:48 am




No, sorry, I don't do NIK–for obvious reasons if you think about it...

:~)

I don't see why you can't use it as a plug in in Photoshop? It isn't unethical? If you find it to be good then it is to your advantage and if you don't then you are free to criticize it?
Title: Lab Color for B/W - Why does it work so well?
Post by: Mark D Segal on February 27, 2010, 07:51:04 am
Quote from: Schewe
Uh well, it's old but try THIS LINK (http://www.pixelgenius.com/tips/schewe-color-bw.pdf) (800KB PDF)



No, sorry, I don't do NIK–for obvious reasons if you think about it...

:~)

But I'm pretty darn sure the channels>layers is still more powerful and flexible (and easy if you record an action to create your layers and layer masks).

Hi Jeff,

Many thanks for the paper. Now that I access it, I seem to recall that I may have seen it before. I have copied it to my hard drive and will do a tryout. BTW, your illustrations there are stunning.

As for NIK, yes of course I had thought about it, and you know that I know the context, but I was simply thinking of the product as a product, because that particular application is unique.  :-)
Anyhow, I'll select an appropriate image or two and do a side-by-side. Won't be this weekend, but I'll report back when I'm done.

(minor edit today 13:45 EST)
Title: Lab Color for B/W - Why does it work so well?
Post by: john beardsworth on March 01, 2010, 10:31:43 am
Quote from: Schewe
Actually, the channels>layers can produce results that are near impossible to reproduce using adjustment layers...

See, if you start with a color image and use the B&W adjustment, Desaturate, Channel Mixer, etc. you get a global conversion to B&W.

There is no easy way to have local control how the conversion will be handled...you can't use layer masks because, well if you mask part of the adjustment layer, the reveal will be back to the color image and trying to place yet another adjustment layer over it becomes problematic...

In terms of B&W conversion in the raw processor, same global deal.

Where the channel>layer is superior is that you can literally paint in a custom B&W conversion area by area and use masks to control what layer are visible. It's pretty easy to do an action that will do the base conversion for you and add hide all layer masks so all you need to do is choose the layer and paint it in via the mask.

I won't claim it's "the best" way...I often do B&W conversions directly in Camera Raw or Lightroom (usually Lightroom where I can make a virtual copy and keep the color & B&W separate). But if you need precise control over different areas in a B&W conversion then the channel>layer is a good solution. Of course, one does have to know how to do it...

My typo didn't help, but notice you quoted my saying "one or more adjustment layers". If you don't want a global conversion but do want to paint in custom conversions, then the second or later B&W adjustment layer would apply its conversion recipe only to whatever colour shows through after the initial, masked B&W adjustment layer - your "reveal". The topmost adjustment layer would need no mask (to be sure that no remaining colour is peeking through). So I'd have the image as a raw file smart object, plus local conversion with 2+ masked adjustment layers.

Where's the advantage? Well, to some extent we're different rather than better. Assuming we're both staying in high bit etc, we'll both end up with the same best quality data, and we don't care if your 3 pixel layers plus masks result in a bigger file than mine (the SO probably makes it even anyway). We can assume your action included a colour layer, so you can always output the same file as a colour image as easily as I can by switching off my adjustment layers. We'll even take the targeted adjustment tool's virtues out of the comparison. And let's assume in each case one does indeed know how to do it....  

I'd say the main difference is in flexibility, which is key because you don't always get things right first time. Let's say that after making the b&w conversion one wants to do something like tweak the lens vignetting correction or adjust capture sharpening or noise reduction - I'm going to find that a lot easier as my adjustment layers have entirely separated the b&w conversion from the image smart object which I can tweak in ACR. That advantage is even greater if one wants to do more substantial in-Photoshop retouching, whether that's cloning or something like perspective or lens correction. Again, the adjustment layers would provide flexibility that your pixels layers can only provide if one really, really knows how.

The end results can be the same, but the workflow's much sweeter.

John