Luminous Landscape Forum

Raw & Post Processing, Printing => Colour Management => Topic started by: Christoph C. Feldhaim on February 18, 2012, 05:40:14 pm

Title: Colormanaging scanned negatives - How to do best ?
Post by: Christoph C. Feldhaim on February 18, 2012, 05:40:14 pm
I want to profile the films I am using and wonder what would be the best method.
Which role plays having a better target ?
I have only a Colorchecker passport - doesn't work creating DNG profiles for TIFFs, since these can't be assigned in LR.

When I scan I am using a simple standard procedure to get positives from my negatives - no adjustments - just a repeatable set of adjustments using Silverfasts "Negafix" function and infrared based dust and scratch removal. So - getting a positive from a negative I have standardized.

I'd like to create an ICC profile I could just assign in PS to have better colors after getting the positive file from the scanned negative.
Just for fun I tried that using Argyll CMS and my colorchecker,
but the profile was crap (The target was taken in overcast weather and not totally protected from reflections).

I think I pretty much understood the basics of colormanagement and
would like to have an as simple as possible workflow to create profiles for my scanned negative films,
but I don't have experience with creating profiles.

Ideas that don't cost tons of money?

Should I use a proper IT8 or Q60 target?
Should use a specific light when taking the image of the target like D50?

Thanks
~Chris
Title: Re: Colormanaging scanned negatives - How to do best ?
Post by: Mark D Segal on February 18, 2012, 05:49:42 pm
Hi Christophe,

I did an extensive tutorial on this subject published on this website here: http://www.luminous-landscape.com/techniques/scanning_colour_negatives_raw_or_not.shtml (http://www.luminous-landscape.com/techniques/scanning_colour_negatives_raw_or_not.shtml)

It predates SilverFast 8 but the principles are the same and you can automate some aspects of it. Don't know whether this is the kind of thing you want, but have a look. Basically I've come to the conclusion that customizing NegaFix is the easiest and best way of doing this.

Cheers,

Mark
Title: Re: Colormanaging scanned negatives - How to do best ?
Post by: Christoph C. Feldhaim on February 18, 2012, 06:11:41 pm
I have read and understood your article - awesome tutorial by the way...

I have one additional question:
How exactly do you set your CMS settings in SF ?

My impression is, they apply the scanner specific profile as a means to get correct input data, but have no solution to correctly render ALL colors by getting film specific.
Of course I tweak and try to optimize the look of an image with the various tools, including the orange mask method you describe.
But how about rendition of the different colors by different films?
ProPhoto does not work in SF because it seems, that there is not a real conversion to ProPhoto but just an assignment.
When I assign the native scanner profile created by the Auto IT8 process my colors become much better.
Adobe RGB works only better, I believe, because its gamut is much nearer to the native scanner gamut.

So what I do is to use the scanner profile for output and I convert (as opposed to assign) to ProPhoto in PS.

What is not solved at this point is the different color rendition of the various films.
I'd like to have the opportunity to eliminate that from the beginning by using a specially tailored profile for each film type.

Title: Re: Colormanaging scanned negatives - How to do best ?
Post by: Mark D Segal on February 18, 2012, 06:33:08 pm
Thanks Christophe, glad you enjoyed the tutorial.

Scanner profiles don't assure accuracy of colour rendition for colour negatives because the film can't really be profiled with icc profiles in the same way positive transparency film/scanner combinations can be. That is why they developed Negafix. The fact is, that you need to use a separate Negafix profile for each colour negative film type you are scanning. And this goes not only for the type, but also for the ISO sensitivity within each type, insofar as - for example - a Kodak Gold 200 will not render colour the same way as a Kodak Gold 400. If you are using SF Ai Studio, there is an Expert Mode which allows you a great deal of customization potential to fine-tune the Negafix profile very correctly.

The most workable combination of settings in CMS I've found is to use your scanner profile as the Input profile, and use Adobe RGB(98) for the Colour Working Space for the reason you mention. OR, you can scan with no profile embedded by chosing one of the HDR modes (and going into CMS and putting <none> everywhere, in General Preferences making) sure your Gamma is 2.2 and check the box "for HDR output" if you are making an HDR scan). Scan with Negafix working, then when you open the image in Photoshop you will get the missing profile warning. At this point I would Assign the scanner profile and Convert to the Working Space - selecting ARG(98) in this instance. 
Title: Re: Colormanaging scanned negatives - How to do best ?
Post by: Schewe on February 18, 2012, 07:09:42 pm
Scanner profiles don't assure accuracy of colour rendition for colour negatives because the film can't really be profiled with icc profiles in the same way positive transparency film/scanner combinations can be.

Mark is correct...E-6 chrome processing tended to be very, very consistent (unless the lab screwed up) so an Ektachrome Q60 was a really good way of profiling the E-6 rendering. C-41 color neg processing tended to be all over the map and stuff varied greatly by film type. Even with the same film type, film processed in one lab would not be at all the same colorimetrically as another lab. That's why you can't really create an ICC profile for scanning negs.
Title: Re: Colormanaging scanned negatives - How to do best ?
Post by: Christoph C. Feldhaim on February 18, 2012, 07:23:17 pm
Mark is correct...E-6 chrome processing tended to be very, very consistent (unless the lab screwed up) so an Ektachrome Q60 was a really good way of profiling the E-6 rendering. C-41 color neg processing tended to be all over the map and stuff varied greatly by film type. Even with the same film type, film processed in one lab would not be at all the same colorimetrically as another lab. That's why you can't really create an ICC profile for scanning negs.

I had hoped to just assign a film specific tailored ICC profile once SF has produced a positive from the negative using Negafix.
This should work, I thought, since the file is a positive at that stage.
But if negative film is so variant it surely doesn't make sense.

I just wonder if the orange masks vary as well - or would it be sufficient to have one mask file per film type so I could automate the process in PS?
Because if they don't vary but the emulsion does any idea about consistent color with negative film would be futile.
Or I would need to shoot a greycard / Colorchecker in D50 (or other consistent) light on every film I expose.
Title: Re: Colormanaging scanned negatives - How to do best ?
Post by: Schewe on February 18, 2012, 07:25:44 pm
I just wonder if the orange masks vary as well

You betcha...and that's one of the big problems trying to scan various emulsions. And again even that could vary lab by lab or over time. There's just no good way to create an ICC profile for neg film that I'm aware of....
Title: Re: Colormanaging scanned negatives - How to do best ?
Post by: Mark D Segal on February 18, 2012, 07:28:59 pm
On top of which not all "orange masks" are "orange" :-)
Title: Re: Colormanaging scanned negatives - How to do best ?
Post by: Christoph C. Feldhaim on February 18, 2012, 07:32:30 pm
If I'd process a negative the way Mark describes by subtracting the orange mask of that specific roll of film - would an ICC profile make sense after this step?

I imagine taking
an image of an IT8 target,
make a raw scan,
subtract the orange mask from the scan and
use that file (now a positive with orangemask removed) for creation of an ICC profile
which I'd subsequently apply to all other images after they have passed the procedure??
Title: Re: Colormanaging scanned negatives - How to do best ?
Post by: Mark D Segal on February 18, 2012, 07:39:52 pm
Why not just do it the easy way of using Negafix to get your positive and embed ARGB(98) as the colour working space? If you've "tuned" your Negafix profile for the batch of film you're scanning, it should look the same in Photoshop as it does in the SilverFast preview converted with the right Negafix profile. And if you need to tweak the Negafix profile for the specific film batch, you have the option in Ai Studio of saving it as a new NegaFix Profile (a custom one) which you can load every time you need to convert an image from that same film batch. By film batch I mean same vendor, type, ISO, film processor and processing date. Once you do that you don't need to worry about IT8 targets and all the rest of it. LaserSoft Imaging made it nice and easy for us, and as I demo'd in that tutorial - all kinds of ways to skin the cat, but none of them do it any better and they are all more complexified.
Title: Re: Colormanaging scanned negatives - How to do best ?
Post by: Christoph C. Feldhaim on February 18, 2012, 07:45:50 pm
I wished Lasersoft would allow us to shoot an IT8 target and use this to create a specific negafix profile so we could have an easy way to adapt.
Though technically somewhat capable I'm not really the type for twiddleing with curves at a computer monitor.
However - the answers helped me a lot since I'm now safe from unnecessary work.

Thanks and cheers
~Chris
Title: Re: Colormanaging scanned negatives - How to do best ?
Post by: Schewe on February 18, 2012, 07:56:55 pm
If I'd process a negative the way Mark describes by subtracting the orange mask of that specific roll of film - would an ICC profile make sense after this step?

Nope...not in my experience...ICC profiles just don't work for neg film. Sorry...your much better off taking Mark's advice and do the correct setup for Lasersoft and get it as good as you can when you scan–knowing the addition corrections will prolly be required in Photoshop-particularly local corrections since a scan app can't really do local corrections...
Title: Re: Colormanaging scanned negatives - How to do best ?
Post by: Mark D Segal on February 18, 2012, 08:01:42 pm
Hi Christoph,

There's nothing LSI is preventing you from doing. The problem is you can't create an ICC profile from the negative of an IT8 target, because the reference values in the target file are all based on positive values of the patches. An ICC profile is designed to characterize your scanner's response to rendition of IT8 patches in positive mode by comparing the colour values of the patches the device renders compared with the correct - positive - values in the target's reference file. I'd love to see how the math in a profile creation program would cope with the disconnect between positive reference file colour values and negative colour values for the same patches from the scanner. Wow, that would be fun! Perhaps a new branch of abstract photography. :-)

Getting back to those Negafix profiles - if you use Curves for adjusting your images in Photoshop, the principle is the same in the NegaFix Expert Mode; yes, it can be a bit "fiddly"; but most of the time most people don't need to get into that.

And yes - always a good idea to avoid needless work :-)

Cheers,

Mark
Title: Re: Colormanaging scanned negatives - How to do best ?
Post by: Mark D Segal on February 18, 2012, 08:03:57 pm


Jeff,

SilverFast 8 can do a lot of local corrections.
Title: Re: Colormanaging scanned negatives - How to do best ?
Post by: Christoph C. Feldhaim on February 18, 2012, 08:46:23 pm
Maybe just for the fun of it I'll try to get hold of an IT8 target and try that thing above -
more for learning and seeing how I'll bump into a wall.
At least it will be educative.
When I asked the Lasersoft guys about using IT8 targets they took it as an idea -
so who knows with what they will come up with in the future ..

Cheers
~Chris
Title: Re: Colormanaging scanned negatives - How to do best ?
Post by: Mark D Segal on February 18, 2012, 08:51:36 pm
Keep us posted what you discover!
Title: Re: Colormanaging scanned negatives - How to do best ?
Post by: MonsterBaby on February 19, 2012, 04:03:33 am
maybe a lil crazy...

but couldnt you take a picture of an reflective it8 target with a certain film (shade outdoor whatever you wanna set up) and then have it developed..

scan it.. use a standard negafix curve for the orange mask so you get a positive.. save it without ICC..

THEN create an ICC profile from the target... !

and there goes your ICC workflow...?

scan.. use standard negfix.. assign new ICC profile.. ??

this way you wouldnt have to fine tune the negfix but just use it for the standard mask
Title: Re: Colormanaging scanned negatives - How to do best ?
Post by: Christoph C. Feldhaim on February 19, 2012, 05:11:26 am
maybe a lil crazy...

but couldnt you take a picture of an reflective it8 target with a certain film (shade outdoor whatever you wanna set up) and then have it developed..

scan it.. use a standard negafix curve for the orange mask so you get a positive.. save it without ICC..

THEN create an ICC profile from the target... !

and there goes your ICC workflow...?

scan.. use standard negfix.. assign new ICC profile.. ??

this way you wouldnt have to fine tune the negfix but just use it for the standard mask

Exactly that is the experiment I'm going to do as outlined above.  ;)
I just found out, I can scan in linear gamma without any curves applied.
And the orange mask removal can also be standardized - So I believe its possible.
If it works in the real world only the experiment will show.
Title: Re: Colormanaging scanned negatives - How to do best ?
Post by: Mark D Segal on February 19, 2012, 08:52:21 am
maybe a lil crazy...

..............

scan it.. use a standard negafix curve for the orange mask so you get a positive.. save it without ICC..

THEN create an ICC profile from the target... !


As Jeff and I have been trying to explain, there is no such thing as a "standard negafix curve" because "orange masks" are all over the place, varying in hue, saturation and lightness depending on the vendor, type, ISO, batch, processor and processing date. But to begin with don't confuse orange mask detection with colour inversion; these are separate issues; orange mask detection is one part of the operation, then the colours need to be inverted - properly. Also, on the mechanical side of it, your photograph of the IT8 target would need to produce a result dimensioned exactly to what a profile creation application could read correctly. Let's see what Christoph comes up with, but I'd be surprised if it turned out to be a more practical workflow than simply using a (perhaps customized) NegaFix profile in SilverFast.
Title: Re: Colormanaging scanned negatives - How to do best ?
Post by: Christoph C. Feldhaim on February 19, 2012, 09:44:06 am
As Jeff and I have been trying to explain, there is no such thing as a "standard negafix curve" because "orange masks" are all over the place, varying in hue, saturation and lightness depending on the vendor, type, ISO, batch, processor and processing date. But to begin with don't confuse orange mask detection with colour inversion; these are separate issues; orange mask detection is one part of the operation, then the colours need to be inverted - properly. Also, on the mechanical side of it, your photograph of the IT8 target would need to produce a result dimensioned exactly to what a profile creation application could read correctly. Let's see what Christoph comes up with, but I'd be surprised if it turned out to be a more practical workflow than simply using a (perhaps customized) NegaFix profile in SilverFast.

And the funny thing is:
Totally controlled and calibrated colors aren't necessarily beautiful, maybe not even THE prerequisite to get beautiful color rendition.
Postprocessing skills, a good calibrated monitor and a good eye are most likely much more important ....
Title: Re: Colormanaging scanned negatives - How to do best ?
Post by: Mark D Segal on February 19, 2012, 09:49:26 am
And the funny thing is:
Totally controlled and calibrated colors aren't necessarily beautiful, maybe not even THE prerequisite to get beautiful color rendition.
Postprocessing skills, a good calibrated monitor and a good eye are most likely much more important ....

Yes, from the artistic perspective this is really true; that said, good artistry still requires control over one's medium and that control starts with reliable methods and techniques, and so much the better if they are also efficient. Not to say that "good art" isn't also created by random walks, but that's not the main point.
Title: Re: Colormanaging scanned negatives - How to do best ?
Post by: Christoph C. Feldhaim on February 19, 2012, 10:53:40 am
Yes, from the artistic perspective this is really true; that said, good artistry still requires control over one's medium and that control starts with reliable methods and techniques, and so much the better if they are also efficient. Not to say that "good art" isn't also created by random walks, but that's not the main point.

Umm ... yes ... I'm a nursery child as you can see here:
(shameless plug (http://www.feldhaim.com/about))
The less I master the technique, the more I become infantile ...  :P
Title: Re: Colormanaging scanned negatives - How to do best ?
Post by: Mark D Segal on February 19, 2012, 11:18:31 am
You're being modest or pulling my leg - some really nice work on your website, so you know what you are doing, and it isn't random walks! Interesting how a generation and a continent apart we had similar parental experiences with a similar outcome.........anyhow I digress.

The real point about this post is that I went back to SilverFast to re-try a few things. Apart from the selection and adjustment of the Negafix Profile, the choice of colour space is the only thing that matters for colour management of a negative scan in SF8 Preferences; for my Nikon SC 5000-ED, ProPhoto is too wide (too much influence of reds) but ARGB(98) produces much better behaved colours.
Title: Re: Colormanaging scanned negatives - How to do best ?
Post by: Christoph C. Feldhaim on February 19, 2012, 01:29:21 pm
I changed my CMS setings to the following:

Input -> Working Space: ICM
Working Space -> Monitor: ICM
Working Space -> Output: RGB

Input: SF_T(Nikon LS 9000 Slide)
Internal: None
Output/Printer: None

No embedding

When I open the file in PS I ASSIGN the SF_T(Nikon LS 9000 Slide) profile and immediately CONVERT to Holmes Chroma 100 (Yes i did it - bough it today along with the 30 Chroma variants).

When I had used ProPhoto as internal Colorspace the reds looked awful and much too oversaturated.
Now with the method above I get good colors (Holmes or Prophoto doesn't make a difference here, I use Holmes for the chroma variants - looks great so far I can judge - much better than using a vibrance layer in PS)
Title: Re: Colormanaging scanned negatives - How to do best ?
Post by: Mark D Segal on February 19, 2012, 02:52:50 pm
Yup - sounds right. ProPhoto produces saturated reds from both Nikon scanners (5000 and 9000). It also did the same from the Minolta 5400 back in those days. Selecting the scanner profile at the scan stage when you are using Negafix is neither here nor there - doesn't do anything. It's the assignment and conversion you did in Photoshop that counts. Good, glad you got a usable workflow. Do you find the Holmes colour space much better for these scans than just using ARGB(98)?
Title: Re: Colormanaging scanned negatives - How to do best ?
Post by: TylerB on February 19, 2012, 03:03:59 pm
well... for what it's worth some of us have been experimenting with various ways to tame color neg results with color management processes, on a film batch basis. I came up with a convoluted approach that results in some of the best color I have ever produced, for one project, from Ektar 120 scans. However it's not anything really workable, and was simply one idea that will be abandoned on the way to better ideas, hopefully.
If we get something workable for humans.. it'll get posted.
In the meantime, I guess dinking with negafix (I too use Silverfast with my Howtek) and a lot of PS work is the way to go...
Tyler
Title: Re: Colormanaging scanned negatives - How to do best ?
Post by: Mark D Segal on February 19, 2012, 03:15:35 pm
well... for what it's worth some of us have been experimenting with various ways to tame color neg results with color management processes, on a film batch basis. I came up with a convoluted approach that results in some of the best color I have ever produced, for one project, from Ektar 120 scans. However it's not anything really workable, and was simply one idea that will be abandoned on the way to better ideas, hopefully.
If we get something workable for humans.. it'll get posted.
In the meantime, I guess dinking with negafix (I too use Silverfast with my Howtek) and a lot of PS work is the way to go...
Tyler

Have you worked on customizing the preferred Negafix profile in the Expert Dialog? If you get that right, you really shouldn't need too much futzing around in Photoshop - at least for basic exposure and colour balance for the same film brand/type/ISO/batch/processor/processing date.
Title: Re: Colormanaging scanned negatives - How to do best ?
Post by: Christoph C. Feldhaim on February 19, 2012, 03:43:38 pm
Yup - sounds right. ProPhoto produces saturated reds from both Nikon scanners (5000 and 9000). It also did the same from the Minolta 5400 back in those days. Selecting the scanner profile at the scan stage when you are using Negafix is neither here nor there - doesn't do anything. It's the assignment and conversion you did in Photoshop that counts. Good, glad you got a usable workflow. Do you find the Holmes colour space much better for these scans than just using ARGB(98)?

I just bought the Holmes Chroma 100 set with the variants today and can say only one thing:
It works better if you want to adapt saturation than using vibrance / saturation  layers.
The size is similar to Prophoto, so if you want to stick with PS/LR saturation adjustments you won't need it, but my first impression is, that its worth it.
Adobe RGB drops/clips a lot of colors my scanner can reproduce, so switching to a wider gamut than AdobeRGB for scanning is a no-brainer for me.
Title: Re: Colormanaging scanned negatives - How to do best ?
Post by: Mark D Segal on February 19, 2012, 04:07:25 pm

Adobe RGB drops/clips a lot of colors my scanner can reproduce, so switching to a wider gamut than AdobeRGB for scanning is a no-brainer for me.

Yes, it is true that the gamut volume measured from the transparency profiles for the Nikon 5000 (and I assume same for your 9000) exceeds RGB(98). But once using ProPhoto, one encounters the redness issue. So if I understand correctly, you are saying that the Holmes colour space gives you the gamut volume without the redness tendency. If so, that sounds like a win-win.
Title: Re: Colormanaging scanned negatives - How to do best ?
Post by: Mark D Segal on February 19, 2012, 04:13:14 pm
Christoph,

Added question to the one above, Holme's page is really out of date, so it's not clear how compatible his profiles are with SilverFast 8 and with Photoshop CS 5. Are these the applications you are using them with?
Title: Re: Colormanaging scanned negatives - How to do best ?
Post by: Christoph C. Feldhaim on February 19, 2012, 04:21:48 pm
I don't think the Holmes space is necessarily better than Prophoto.
The advantage of it is the chroma variants.
My impression is, that the conversion from the scanner input space into the working space in SF8 is simply bugged.
To me it looks as if Prophoto just was assigned and not converted and that the conversion did not work when using Prophoto as working colorspace in SF8.
ASSIGNING the scanner colorspace in PS and then CONVERTING to the larger gamut in PS did the trick.
This should also work with Prophoto.
I will call Lasersoft next week and ask them about it.

I mean:
What happens when we profile the scanner?
We put in a target with known XYZ/LAB values and scan it.
We get a profile which connects the numbers coming out of the scanner with the real world colors.
When suddenly after changing the colorspace a number which represents a real world red tone shows an out of bound extreme red something has gone wrong.
Since Prophoto is a wide gamut colorspace which allows these extreme reds, I believe the number which represents a sane red in the measured scanner profile/colorspace and which suddenly represents an extreme color has been wrongly converted or just been assigned.
So - basically I believe its a bug.
A conversion from a colorspace/profile which gives good color to a larger colorspace which contains the original colorspace should never lead to these extreme colors.
I tried all rendering intents, and the reds were always out of bounds - so I believe its a bug.
Title: Re: Colormanaging scanned negatives - How to do best ?
Post by: dmerger on February 19, 2012, 04:44:01 pm
My impression is, that the conversion from the scanner input space into the working space in SF8 is simply bugged.
To me it looks as if Prophoto just was assigned and not converted and that the conversion did not work when using Prophoto as working colorspace in SF8.

Same here (with an earlier version of SF).  This problem has been known and discussed for a long time.
Title: Re: Colormanaging scanned negatives - How to do best ?
Post by: Mark D Segal on February 19, 2012, 05:18:41 pm
I don't think the Holmes space is necessarily better than Prophoto.
The advantage of it is the chroma variants.
My impression is, that the conversion from the scanner input space into the working space in SF8 is simply bugged.
To me it looks as if Prophoto just was assigned and not converted and that the conversion did not work when using Prophoto as working colorspace in SF8.
ASSIGNING the scanner colorspace in PS and then CONVERTING to the larger gamut in PS did the trick.
This should also work with Prophoto.
I will call Lasersoft next week and ask them about it.

I mean:
What happens when we profile the scanner?
We put in a target with known XYZ/LAB values and scan it.
We get a profile which connects the numbers coming out of the scanner with the real world colors.
When suddenly after changing the colorspace a number which represents a real world red tone shows an out of bound extreme red something has gone wrong.
Since Prophoto is a wide gamut colorspace which allows these extreme reds, I believe the number which represents a sane red in the measured scanner profile/colorspace and which suddenly represents an extreme color has been wrongly converted or just been assigned.
So - basically I believe its a bug.
A conversion from a colorspace/profile which gives good color to a larger colorspace which contains the original colorspace should never lead to these extreme colors.
I tried all rendering intents, and the reds were always out of bounds - so I believe its a bug.

When you scan negatives in SilverFast and you use the Negative image type, this disables the effect of input profiles altogether. You can try this with a range of input profiles that you know wildly misrepresent your scanner's colour rendering behaviour when used with positives, and when used with negatives they don't make a particle of difference. In fact, in SF 6.x there wasn't even an option to adopt an input profile with the Negative film type selected. It was grayed-out in CMS. In SF8 it isn't grayed-out, but may just as well have been, because they don't do anything. Stick in <none> or a profile for the wrong scanner and the result is the same. Now, regardless of how you treat the input profile, when it comes to the internal profile (colour working space) - that selection does make a difference. If you select ARGB(98), and you have a decent NegaFix profile, the rendition comes out OK in both SilverFast and identically in Photoshop. But you'll get the Profile Mismatch warning when you open the image in Photoshop. It will tell you that the embedded profile is ARGB(98) - (not a scanner profile) which is correct, and give you the usual options. If you chose to either use the embedded profile or convert to the working space, the colour appearance remains identical, because Photoshop simply remaps those ARGB(98) values to their equivalents in ProPhoto. But by doing that of course we haven't added anything to the image. Only the scale changes. What wasn't scanned-in to begin with won't reappear now. SO, let us say we now select ProPhoto as the working space in SF8. That immediately wrecks the colours in the way we agree it does - reddish. Now, you open that wreck in Photoshop and there is no Profile Mismatch warning because there is no mismatch between the embedded profile and the working space, so you see the same wreck. So yes, definitely something is happening with ProPhoto in SilverFast. This by the way is nothing new. It has been forever so in Ai 6.x too. And perhaps before that. And they have completely re-written the code for SF8 and reviewed all the colour management stuff. Not to say what we're observing isn't a bug, but at this stage i wonder how it survived if it is. It will be interesting to hear of their explanation when you speak to them.
Title: Re: Colormanaging scanned negatives - How to do best ?
Post by: MonsterBaby on February 19, 2012, 05:56:27 pm
regarding my post.. yes i know there are def. different orange masks (i developed some GDR orwo color negs myself).. and again.. i wont try this method as i totally agree with you that silverfast negfix is prob. all we need.. but im still pretty sure this process will work!

if i want to scan an orwo film.. of course i have to use orwo for the profile!..

but another aspect you guys talk about is the prophoto "thing" with negafix.. actually i have the feeling the whole colormanagement in silverfast doesnt work for negatives!!

i get different colors weather i use adobe s or prophoto.. although i dont assign it but use it in silverfast ist working space!.. thats a bug right?

it should always keep the konstant colors and use the scanners profile or gamut as ICC and then convert to my workin space and not asign..

thats typical to get redish reds.. if you just assign prophoto!
Title: Re: Colormanaging scanned negatives - How to do best ?
Post by: sertsa on February 19, 2012, 06:21:01 pm
If it is a bad idea to piggyback on this thread, I will start a new one but I've been struggling with something similar.  Came across an old slide copier and have been playing with shooting my negs with my DSLR.  It works pretty well but have had no success with making a decent positive image.  Is there any way to get something workable from a raw DSLR image of a negative?  Can I feed an image into Silverfast without a scanner (seems unlikely, but have never used Silverfast) and then do as you all are doing?
Title: Re: Colormanaging scanned negatives - How to do best ?
Post by: Christoph C. Feldhaim on February 19, 2012, 06:26:27 pm
If it is a bad idea to piggyback on this thread, I will start a new one but I've been struggling with something similar.  Came across an old slide copier and have been playing with shooting my negs with my DSLR.  It works pretty well but have had no success with making a decent positive image.  Is there any way to get something workable from a raw DSLR image of a negative?  Can I feed an image into Silverfast without a scanner (seems unlikely, but have never used Silverfast) and then do as you all are doing?

Just a wild guess but:
Maybe the heavy orange tone of the negatives somehow exceeds the gamut your DSLR can capture and you'll get some clipping and thus no good colors.

Title: Re: Colormanaging scanned negatives - How to do best ?
Post by: dmerger on February 19, 2012, 06:33:35 pm
ColorNeg/ColorPerfect is a PS plugin that may help.  I tried a demo version a while ago for scanning negatives as positives, then removing the orange mask and inverting.  I didn't work with it much and didn't get good results immediately.  Maybe with a little more learning I could have achieved better results.  http://www.c-f-systems.com/Plug-ins.html#plugdesc
Title: Re: Colormanaging scanned negatives - How to do best ?
Post by: sertsa on February 19, 2012, 06:42:47 pm
Just a wild guess but:
Maybe the heavy orange tone of the negatives somehow exceeds the gamut your DSLR can capture and you'll get some clipping and thus no good colors.

This may be true, but I think I'm not even getting to that point.  From this discussion I'm getting that somehow the orange cast be compensated for and then the colors inverted, you all are relying on the Silverfast scanning software to do these steps.  I guess my question is can this be done without silverfast.  What if you had a simple scanner and software and ended up with just a scan of your negative just as it is, negative and orange, in a tiff (or whatever, in my case it would be a NEF).  Is there any way to get from that to a half decent positive image?
Title: Re: Colormanaging scanned negatives - How to do best ?
Post by: sertsa on February 19, 2012, 07:30:56 pm
ColorNeg/ColorPerfect is a PS plugin that may help.  I tried a demo version a while ago for scanning negatives as positives, then removing the orange mask and inverting.  I didn't work with it much and didn't get good results immediately.  Maybe with a little more learning I could have achieved better results.  http://www.c-f-systems.com/Plug-ins.html#plugdesc

Will look at this , thanks.
Title: Re: Colormanaging scanned negatives - How to do best ?
Post by: Mark D Segal on February 19, 2012, 10:00:34 pm
If it is a bad idea to piggyback on this thread, I will start a new one but I've been struggling with something similar.  Came across an old slide copier and have been playing with shooting my negs with my DSLR.  It works pretty well but have had no success with making a decent positive image.  Is there any way to get something workable from a raw DSLR image of a negative?  Can I feed an image into Silverfast without a scanner (seems unlikely, but have never used Silverfast) and then do as you all are doing?

If you have the SilverFast HDR application, you can bring a TIFF file of a negative image into SilverFast HDR where the Negafix profiles are also bundled, so you could give it a try. SilverFast HDR is now available as a free pre-release download on the SilverFast website, so it is a good time to try this out because you don't need to pay anything - yet. Once they release the commercial version of the application, of course it will no longer be free. Pre-release versions have a limited life-span.
Title: Re: Colormanaging scanned negatives - How to do best ?
Post by: Mark D Segal on February 19, 2012, 10:03:01 pm
ColorNeg/ColorPerfect is a PS plugin that may help.  I tried a demo version a while ago for scanning negatives as positives, then removing the orange mask and inverting.  I didn't work with it much and didn't get good results immediately.  Maybe with a little more learning I could have achieved better results.  http://www.c-f-systems.com/Plug-ins.html#plugdesc

Has to be some of the most dense, convoluted and unreadable material on the internet. Why should people subject themselves to this punishment when there are simple and effective alternatives?
Title: Re: Colormanaging scanned negatives - How to do best ?
Post by: Mark D Segal on February 19, 2012, 10:20:56 pm
regarding my post.. yes i know there are def. different orange masks (i developed some GDR orwo color negs myself).. and again.. i wont try this method as i totally agree with you that silverfast negfix is prob. all we need.. but im still pretty sure this process will work!

if i want to scan an orwo film.. of course i have to use orwo for the profile!..

but another aspect you guys talk about is the prophoto "thing" with negafix.. actually i have the feeling the whole colormanagement in silverfast doesnt work for negatives!!

i get different colors weather i use adobe s or prophoto.. although i dont assign it but use it in silverfast ist working space!.. thats a bug right?

it should always keep the konstant colors and use the scanners profile or gamut as ICC and then convert to my workin space and not asign..

thats typical to get redish reds.. if you just assign prophoto!

I wonder how many people in the world use ORWO film these days? No matter, it isn't mainstream stuff that industry is rushing out to cater for. As a negative film, and as we've been explaining in this thread, there is no ICC profiling for it. You need to use another approach for neutralizing the orange mask, decompressing the contrast and inverting the colours. NegaFix in SilverFast would be a decent start, because you have a choice of about 127 different profiles from which to build on. Given what ORWO film was, you would probably have the best chances within the Agfa group. But most likely you will need to create a custom Negafix profile by using the Expert Dialog controls in the Ai Studio version of SilverFast.

Colour management does work with negatives in SilverFast - any such colour control operations require at least a colour working space. The observation of reddishness emerging from the combination of NegaFix and ProPhoto doesn't nullify the whole functionality of colour management in SilverFast when handling negatives.

I've never heard of "adobe s" so I can't comment on that.

As we've been trying to explain here, there is no scanner profile for handling colour negatives. And reds should be reddish. It's the other colours that shouldn't be reddish.

I'm not at all convinced that this observed reddishness has anything to do with whether colours are rendered from an assigned profile versus converting the colours to Pro Photo. That remains to be determined.

Title: Re: Colormanaging scanned negatives - How to do best ?
Post by: Mark D Segal on February 19, 2012, 10:26:26 pm
This may be true, but I think I'm not even getting to that point.  From this discussion I'm getting that somehow the orange cast be compensated for and then the colors inverted, you all are relying on the Silverfast scanning software to do these steps.  I guess my question is can this be done without silverfast.  What if you had a simple scanner and software and ended up with just a scan of your negative just as it is, negative and orange, in a tiff (or whatever, in my case it would be a NEF).  Is there any way to get from that to a half decent positive image?

Yes there is. I have explained all this step-by-step in extensive detail in the tutorial I created for this website and is hyperlinked above in this thread. It all works, but SilverFast's NegaFix is just so much easier and produces very good results when used properly.
Title: Re: Colormanaging scanned negatives - How to do best ?
Post by: dmerger on February 20, 2012, 12:12:34 am
Has to be some of the most dense, convoluted and unreadable material on the internet. Why should people subject themselves to this punishment when there are simple and effective alternatives?

Reminds me of what a lot of people say about Silverfast.   ;D

Yes, the web site is pretty dense, but actually using ColorNeg/ColorPerfect isn't any more difficult than using Silverfast.  It's probably a little easier.  As far as I remember, ColorNeg/ColorPerfect uses negative film profiles in a manner similar to Silverfast.
Title: Re: Colormanaging scanned negatives - How to do best ?
Post by: MonsterBaby on February 20, 2012, 05:05:28 am
@mark..

 i just used orwo as an example of a very different mask. thats all ;-) and like i said.. i am not going to try that either as negfix does it for me.! even with orwo. .;-) it was just a theoratically aproach.

"i get different colors weather i use adobe s or prophoto" .. sorry.. if i was a little fast here.. i am sure you have heard about it:

i get different colors weather i use AdobeRGB or sRGB or proPHOTO  ;)

and this cannot be right!.. there cannot be a colorshift when i use different WORKING spaces.. there can be clipping of course but not shifting.

its very obvious that negfix "produces" f.e. a red that is 255/0/0.. and then just assigns the workspace to it.. by "accident" Adobe RGB seems to fit best..
Title: Re: Colormanaging scanned negatives - How to do best ?
Post by: Christoph C. Feldhaim on February 20, 2012, 05:17:31 am
I just had a call to Lasersoft and the guy I was talking to admitted that there is a problem and they are working on fixing it.

He basically said that in the moment it seems so, that the numbers of the file are being kept in AdobeRGB and Prophoto (or sRGB) is just assigned and that the conversion seems not to happen.
This sounds like AdobeRGB would be always the internal colorspace, no matter what you do.
But they are still examining it and he promised to send me a beta version with the fix if they find the bug.

I am not sure what happens when not using an internal colorspace at all in SF8 - if the numbers of the file represent the scanners native RGB (in my case "SF_T(Nikon LS9000)") or AdobeRGB.
I'll check against a target visually as soon as possible to see whats the best solution.
Title: Re: Colormanaging scanned negatives - How to do best ?
Post by: MonsterBaby on February 20, 2012, 07:43:44 am
"He basically said that in the moment it seems so, that the numbers of the file are being kept in AdobeRGB and Prophoto (or sRGB) is just assigned and that the conversion seems not to happen. "

isnt that what i said ? well as long as no one else noticed it.. ;-)   :o :o :o ;D

the bug is only with the negs tho.. CM works nicely with slides
Title: Re: Colormanaging scanned negatives - How to do best ?
Post by: Mark D Segal on February 20, 2012, 08:32:15 am
Reminds me of what a lot of people say about Silverfast.   ;D

Yes, the web site is pretty dense, but actually using ColorNeg/ColorPerfect isn't any more difficult than using Silverfast.  It's probably a little easier.  As far as I remember, ColorNeg/ColorPerfect uses negative film profiles in a manner similar to Silverfast.

Dean, if you haven't peaked over there for a long time go over to SilverFast.com and download a demo of SilverFast 8. They got the message and you'll be pleasantly surprised.
Title: Re: Colormanaging scanned negatives - How to do best ?
Post by: Mark D Segal on February 20, 2012, 08:53:52 am
I just had a call to Lasersoft and the guy I was talking to admitted that there is a problem and they are working on fixing it.

He basically said that in the moment it seems so, that the numbers of the file are being kept in AdobeRGB and Prophoto (or sRGB) is just assigned and that the conversion seems not to happen.
This sounds like AdobeRGB would be always the internal colorspace, no matter what you do.
But they are still examining it and he promised to send me a beta version with the fix if they find the bug.

I am not sure what happens when not using an internal colorspace at all in SF8 - if the numbers of the file represent the scanners native RGB (in my case "SF_T(Nikon LS9000)") or AdobeRGB.
I'll check against a target visually as soon as possible to see whats the best solution.

First, this is excellent news - better late than never.

As to what's been happening, I doubt this is an issue related to whether profiles are assigned or there is a conversion. My hunch is that it's a mapping issue.

If you scan a negative (at least in one of these Nikon scanners - in my case SC5000ED) with no profiling whatsoever and open it in Photoshop, you get the missing profile notice. If you assign ProPhoto you will get the influence of excessive reds. If you assign ARGB(98) it will look fine. If you assign ARGB(98) and convert to the working space (ProPhoto) in Photoshop it's also fine. The problem only occurs when you travel straight from the scan to ProPhoto in Photoshop, or chose ProPhoto as the internal space in SilverFast. If no working space is assigned to the scan, my understanding is that the unmanaged data is sent from the scanner unmanaged and stays that way until you make a decision about how to manage it. Anyhow, let us hope that this will soon be academic.
Title: Re: Colormanaging scanned negatives - How to do best ?
Post by: Christoph C. Feldhaim on February 20, 2012, 08:58:26 am
The simple fix in the moment is:

Any positive file created from a neative scan using Negafix requires AdobeRGB as first assigned colorspace. Be it in Silverfast or in PS later.
This is mandatory for now until they have fixed it.
Assigning my scanner colorspace just worked because it doesn't differ too much from AdobeRGB.
Title: Re: Colormanaging scanned negatives - How to do best ?
Post by: Mark D Segal on February 20, 2012, 09:01:31 am
The simple fix in the moment is:

Any positive file created from a neative scan using Negafix requires AdobeRGB as first assigned colorspace. Be it in Silverfast or in PS later.
This is mandatory for now until they have fixed it.
Assigning my scanner colorspace just worked because it doesn't differ too much from AdobeRGB.

Correct, and in fact if you are making prints, the bottom line is the relationship between the gamut shape and volume of your printer profile versus that of the scan, and the bottom line below that bottom line is the kind of image it is and what differences our eyes can see!
Title: Re: Colormanaging scanned negatives - How to do best ?
Post by: dmerger on February 20, 2012, 11:47:44 am
Christoph, your experience with Silverfast and mine are similar.  Using aRGB solves the profile mismatch problem.  Of course, as you already mentioned, using aRGB means that you may not get all the colors your scanner can produce. 

A while ago, I did a few general scanning tests.  I was just trying to determine which scanning software produced better negative scans with my scanner.  My tests were not intended to compare gamut. I randomly selected three photos.  To my surprise, one of them showed gamut clipping with Silverfast and aRGB compared to my scanner’s native color space. Converting from my scanner’s native color space to PhoPhoto didn’t show any clipping.

BTW, the photo wasn’t one where I would have expected a gamut larger than aRGB.  It wasn’t a colorful sunset or saturated flowers.  However, I didn’t print the photo, so I don’t know if the gamut differences would have been noticeable in a print, but I suspect not. In any event, I know you’re fully aware of gamut issues.  Just thought you’d be interested in my experience.
Title: Re: Colormanaging scanned negatives - How to do best ?
Post by: Christoph C. Feldhaim on February 20, 2012, 12:02:25 pm
After all we can overcome these gamut issues by using the method Mark described in his tutorial.
Using an HDR scan with the real raw data from the scanner and the orange mask subtraction trick no colors should be lost.
I'll do some further testing tonight...
Title: Re: Colormanaging scanned negatives - How to do best ?
Post by: Christoph C. Feldhaim on February 21, 2012, 02:58:34 pm
After some testing today I found out the following:

1. You can apply a Gamma value to the HDR scans of Silverfast 8  in the preferences by activating the "for HDR output" checkbox right of the Gamma setting

2. If you deactivate it you get a Gamma of 1 (linear) which seems to be the true raw data. Leaving it activated and setting Gamma to 1 has the same effect.

3. Now the interesting thing:
If you scan with a Gamma of 1 and try Marks method of reversal using the orange mask in photoshop there still is a strong color cast. Marks method doesn't work anymore (He recommends Gamma 2.2)

4. BUT:
If you do this with a Gamma set to 5.0 (the maximum possible) the scan is much lighter, but the reversal process using the orange mask produces a far better removal of the color cast than using a Gamma of 1 or a Gamma of 2.2 as recommended in Marks article.


I am still doing some more testing, since I am not completely sure yet, what this Gamma acrobatics does to the histogram, but in the moment it looks not (yet) too bad.

EDIT:
Attached jpegs derived from the PSDs made from the scans. See filename for Gamma info.
Tonality was restored after the inversion by orange mask subtraction with a simple levels adjustment.
Title: Re: Colormanaging scanned negatives - How to do best ?
Post by: Christoph C. Feldhaim on February 21, 2012, 03:21:59 pm
Here are the PSDs shrunk to 25%
Title: Re: Colormanaging scanned negatives - How to do best ?
Post by: Mark D Segal on February 21, 2012, 03:38:31 pm
The Gamma Acrobatics, as you put it, affects mid-tone brightness and contrast. It is similar to adjusting the middle slider of the Input Histogram in Levels in Photoshop. You are correct that a Gamma value of 1.0 is the "more raw" data insofar as it is linear. The problem with it is that it's almost always much to dark to be useful. That is why they provided that check-box "for HDR output" - to help make sure you get user-friendly brightness and contrast in external applications.

I never experimented with Gamma 5.0 simply because I figured it would be far too bright to be useful, but just as well you are thinking out of the box and coming up with some interesting outcomes. It surprises me however that 2.2 results in the kind of cast your image shows. I didn't get that in mine, which would have shown through the memory colours in the test image I was using. What this means is that brightness is affecting hue in the reversal process. Worth further investigation!
Title: Re: Colormanaging scanned negatives - How to do best ?
Post by: Christoph C. Feldhaim on February 21, 2012, 03:43:33 pm
Yes - for me it was totally unexpected as well.
Title: Re: Colormanaging scanned negatives - How to do best ?
Post by: Christoph C. Feldhaim on February 22, 2012, 06:47:45 am
After some thinking it appears totally clear to me why happened what happened what I described above with the various Gamma settings.

Actually the idea of just subtracting the orange mask to get good color is naive.
The idea of just subtracting the orange masks is based on the assumption, that the gradation curve is linear and has a slope of 1 and that all three color curves are strictly parallel.
This is obviously not the case.
Neither the 3 curves are linear, nor do they have a slope of 1 nor are they parallel.
Using the "right" Gamma value can partially, but not completely correct this error and
this is more or less a random result.
A correct neutral grey point (and whitepoint) must be defined additionally the blackpoint (orange mask).
The nonlinearity of the films gradation curve is where the characteristics of the film lie (pun intended),
and all three curves (for each basic color) are different and have different symmetry properties and slopes, but
the big color shift we can see in the images above comes from the wrong whitepoint and increasing the Gamma just changed this.

So - the proper method would be:

1. Orange mask subtraction like described
2. Definition of the correct whitepoint (or neutral grey in the almost linear middle of the curve) to get rid of the colorcast.
3. Levels adjustment (Luminosity)

Setting the correct greypoint or whitepoint in this linear transformation will make it possible to work with any gamma value.

The amount of the mistake depends on the film curve characteristics and
since the curve is modified by the applied Gamma, Gamma has an influence on the mistake.

I hope that could clear up things a bit.

Orange mask subtraction just does an offset correction, but not the necessary slope correction of the curves.

Cheers
~Chris
Title: Re: Colormanaging scanned negatives - How to do best ?
Post by: Mark D Segal on February 22, 2012, 10:35:39 am
Hi Chris,

I think what you are saying boils down to the following propositions.  Starting with colour cast - the colour of the mask is uniform so once it is neutralized it should be neutralized for the entire image, and if there remains a colour cast after neutralizing the hue of the mask it should not be on account of the mask. Colour casts not related to the mask should be neutralized by correct setting of the black and white points in the "de-masked" image (the minimum necessary intervention for doing this can vary; sometimes one needs to correct black point, white point and middle gray; sometimes one or two of them work fine). Turning to luminosity, The scan of the image is linear unless Gamma > 1.0 is applied in the scan software, but of course the film curves are as you say totally non-linear - by design. So we are always making linear scans (if we set gamma at 1.0) of non-linear media, and needs adjustment in Levels or Curves. So I think we end-up in the same place: get rid of the orange mask bias, correct remaining cast and deal with luminosity. All that still doesn't get to the bottom of why you got better results from Gamma 5.0 than 2.2 or so. That one I need to mess around with both in my mind and with the tools, as soon as time permits!
Title: Re: Colormanaging scanned negatives - How to do best ?
Post by: Christoph C. Feldhaim on February 22, 2012, 11:55:36 am
Gamma compresses on one side of the curve and expands on the other side of the curve if it is not equal 1, since its an exponential function.

f(x)=xgamma

for gamma = 1 there is f(x)=x

x values are normalized between 0 and 1.

This sort of shift moves the curve in a way which probably comes near to the required setting of white  point (black point we have set with orange mask removal).
It appears applying a high gamma as I did comes close to what happens if the white point has been set properly.
I'll do some drawing curves and stuff tonight to understand it better, but as a first step in understanding this it appears to me just so. In the moment I see it as a mathematical problem which has to do with the nature of the gamma function and how it transforms the curves.
Title: Re: Colormanaging scanned negatives - How to do best ?
Post by: Mark D Segal on February 22, 2012, 12:03:13 pm

It appears applying a high gamma as I did comes close to what happens if the white point has been set properly. .


Could be - looking forward to what you find.

And yes, the black point should be remapped to neutral black by removing the mask if done from unexposed film.
Title: Re: Colormanaging scanned negatives - How to do best ?
Post by: Christoph C. Feldhaim on February 22, 2012, 03:19:24 pm
I have played a bit with the gamma and the transformation a linear curve can get by applying gamma.

The formulas:

Gamma (Yellow):  y= x^Gamma

Red linear:    y= 0.8x+0.10
Green linear:  y= 0.8x+0.20
Blue linear:   y= 0.8x+0.25

Red corrected curve:   y=0.10-(0.8x+0.10)^Gamma
Green corrected curve: y=0.20-(0.8x+0.20)^Gamma
Blue corrected curve:  y=0.25-(0.8x+0.25)^Gamma

I have not yet an  idea what it means, nor am I sure if have applied correct x and y values, but if I'm not mistaken values from gamma acrobatics are normalized to values between 0 and 1.
This is as a help for thinking what might have happened above.
No idea if it has any declarative value.
I also am not sure if I did the subtraction correctly.

Ideas about the formulas?



(Rendering done with POVRay 3.7 beta)