Luminous Landscape Forum

Raw & Post Processing, Printing => Printing: Printers, Papers and Inks => Topic started by: natas on May 03, 2011, 10:20:54 am

Title: 16bit printing...your thoughts?
Post by: natas on May 03, 2011, 10:20:54 am
Hey guys,

I am in need of an upgrade, my current mac is just not cutting it. Editing 40mp files is killing me but I am having a hard time deciding on what to do. The mac pro's are way behind and from everything I have read out there and update is not coming anytime soon. So I was thinking of switching back to a PC....but now I am having second thoughts because I will no longer have 16bit printing support for my Epson 7900. Should I allow this to be a show stopper? Does 16bit printing really make a huge difference.

I know you guys are going to come back and say to just do a test but I am color blind (red+green) so I may not be able to see the difference.
Title: Re: 16bit printing...your thoughts?
Post by: digitaldog on May 03, 2011, 10:35:48 am
Does 16bit printing really make a huge difference.

At this time, no. At least sending good high bit data to the printer (of which only a few will pass that high bit data). You do want to work in high bit! But sending the data to the few drivers that can take all that data, its difficult to see a difference in all but the most demanding images (stuff with very smooth gradients). And then, you need to have your nose touching the prints.
Title: Re: 16bit printing...your thoughts?
Post by: natas on May 03, 2011, 10:39:06 am
Thanks DigitalDog. I always work in 16bit when editing :)
Title: Re: 16bit printing...your thoughts?
Post by: Mark D Segal on May 03, 2011, 10:43:13 am
Excuse me - MacPro way behind? Way behind what, how? Please tell me. I'm using a mid-2010 MacPro with 24GB of RAM, 24 effective core processing capacity, 2.63 GHz clock-speed and this thing is blazing fast and rock solid even processing 1 gigabyte files. There are PCs that can do this too, if you want all the performance-degrading baggage that comes with virus, spyware and malware protection you need for those systems (but by the way we may soon be needing for Mac too, as the cyber-criminals have now developed a toolkit for hacking into OSX).

No - from what I've read and observed of my own work sending images to the 4900 in both the 8-bit and 16-bit print options, one doesn't really need a 16-bit print path for a conventional RGB to inkjet workflow, because the heavy-lifting where 16-bit is important happens at the image preparation phase.
Title: Re: 16bit printing...your thoughts?
Post by: neile on May 03, 2011, 11:12:31 am
Ditto to what everyone else has said. Here's my blog entry where I did side-by-side comparisons: http://www.danecreekfolios.com/blog/2010/7/6/is-there-a-difference-printing-16-bit-instead-of-8-bit.html.

Neil
Title: Re: 16bit printing...your thoughts?
Post by: natas on May 03, 2011, 11:35:22 am
Excuse me - MacPro way behind? Way behind what, how? Please tell me. I'm using a mid-2010 MacPro with 24GB of RAM, 24 effective core processing capacity, 2.63 GHz clock-speed and this thing is blazing fast and rock solid even processing 1 gigabyte files. There are PCs that can do this too, if you want all the performance-degrading baggage that comes with virus, spyware and malware protection you need for those systems (but by the way we may soon be needing for Mac too, as the cyber-criminals have now developed a toolkit for hacking into OSX).

Well the new i7 Sandybridge processors are fast...really fast. Test show that the i7-2600 beats the 6core Xeon in PS CS5 test. The new motherboards also support 32Gigs of ram. . Plus you can get this system (with 24Gigs of ram) for less than $1600 compared to $3699 base (3gigs of ram).

Yes a dual 6core is going to beat the i7 in CPU test but I seem to recall that in CS5 test it will not. That's all I plan to use this machine for. CS5, Lightroom and printing.

I am willing to pay the extra for a Mac System (I have 3 Mac's in the house) but Apple needs to do something.

And I guess I went a little to far by saying way behind ;) ...but its really hard right now to shell out that much money for a system that is actually slower at double the price.

Yes the Spyware and all that jazz is a major issue for me...this is why I have all macs in the house. I am just really annoyed that I cannot get the latest system from Apple without having to get an Imac.
Title: Re: 16bit printing...your thoughts?
Post by: Mark D Segal on May 03, 2011, 11:40:59 am
Not the place or time to get into a Mac-PC thing, but when I did a rigorous feature-for-feature comparison last year between buying a Dell and a Mac with as closely matched a feature set I could assemble, the price difference was minimal. Yes, build-it-yourself solutions are bound to be cheaper, but then you need to build it yourself and trouble-shoot it accordingly. (HP/Compaq and Gateway were not compared.)
Title: Re: 16bit printing...your thoughts?
Post by: natas on May 03, 2011, 11:57:52 am
Not the place or time to get into a Mac-PC thing, but when I did a rigorous feature-for-feature comparison last year between buying a Dell and a Mac with as closely matched a feature set I could assemble, the price difference was minimal. Yes, build-it-yourself solutions are bound to be cheaper, but then you need to build it yourself and trouble-shoot it accordingly. (HP/Compaq and Gateway were not compared.)

That may of been the deal last year, but as of right now it's not the case....well unless you build a system with Xeon's :)

It would be awesome if Apple came out with a new line. I understand the need for Xeon's in servers but for guys like us (unless you get the 2 cpu systems) I really think its pointless. If Apple came out with a desktop machine with i7 CPU's in a tower I think they would sell much better than the Mac Pro's. Price them in the $1000-2500 range. I bet gamers would even go for them.

Anyway I guess I really need to think this over. I am really having a hard time deciding on what to do. Part of me wants to just suffer 6 months and wait for the next Mac pro and the other part of me wants to just go to Dell's website and get a i7-2600 for $1600

Title: Re: 16bit printing...your thoughts?
Post by: Scott Martin on May 03, 2011, 12:00:12 pm
There's some debate about what printers can actually process high bit data. Processing data at levels higher than 8 bits is computationally and financially expensive. Do $300 printers really have the hardware needed to process 16 bit data that the driver is now capable of sending to it? Highly unlikely.

Canon is the only manufacturer that makes a big deal about their onboard beefy L-COA processor being able to handle high bit depth data. They are quite open about this conversation and admit that their testing showed a "sweet spot" at 12 bits and have chosen to implement 12 bit processing on their iPF printers for that reason. When I asked Epson's and HP's product managers about this directly they were quick to say "No comment" although their evangelists are quick to say "Yes all Epson printers, even small ones can process full 16 bit data."

As always, real world testing trumps theory and the typical marketing oriented talk that permeates our industry. From my own and my client's testing, we are only seeing 16 bit printing improvements on Canon iPF printers and then only slight as seen in gradation smoothness. Interestingly enough, XRite's new i1Profiler has proven that profile quality has more effect on output smoothness than bit depth. With an excellent i1P profile you'd be hard pressed to say that an 8 bit granger rainbow isn't totally smooth on an 9900, for example.

As others have pointed out, high bit depth development is the key area where working at high bit depths really matters. Capture would be a close second and printing appears dead last as far as importance goes. Best to prioritize having an superb output profile there.
Title: Re: 16bit printing...your thoughts?
Post by: natas on May 03, 2011, 12:04:57 pm
Thanks for the reply Onsight. That was very helpful!
Title: Re: 16bit printing...your thoughts?
Post by: Scott Martin on May 03, 2011, 12:13:09 pm
It would be awesome if Apple came out with a new line

Thunderbolt/Sandybridge iMacs released this morning, new Mac Pros to follow. Thunderbolt is going to make real differences for us. Even if we can't get the drives till next month it's really nice to know that Apple's already up to speed. Fingers crossed for a matte surface, Thunderbolt 27" Cinema Display....

Thanks for the reply Onsight. That was very helpful!

As my taco joint waiter often says to gringos like me "grassy-ass!"
Title: Re: 16bit printing...your thoughts?
Post by: Sven W on May 03, 2011, 12:44:23 pm
Does 16bit printing really make a huge difference?

Not at all on RGB. But when printing true (one channel) B&W in 8 bit, you play
with only 256 shades of grey. Todays top printers with their three or four black inks can produce more than 256
shades and you'll see a small improvement in 16 bit (65536 possible shades).
And for the flexibility to always edit in 16 and just print it.
/Sven
Title: Re: 16bit printing...your thoughts?
Post by: hjulenissen on May 03, 2011, 03:22:56 pm
I believe that paper can (at best) do a 100:1 contrast, and that 8 bit using ideal gamma encoding is in principle enough for that range to avoid visible banding.

However, there are practical deviations from my idealised case. If the printer does heavy internal processing and/or processing inside the 8-bit domain is done without proper regard to dithering, there may be reasons to do >8bit for specific combinations of gear.

-h

http://www.poynton.com/PDFs/GammaFAQ.pdf
Quote
At a particular level of adaptation, human vision responds to about a
hundred-to-one contrast ratio of intensity from white to black. Call these
intensities 100 and 1. Within this range, vision can detect that two intensi-
ties are different if the ratio between them exceeds about 1.01, corre-
sponding to a contrast sensitivity of one percent.
To shade smoothly over this range, so as to produce no perceptible steps,
at the black end of the scale it is necessary to have coding that represents
different intensity levels 1.00, 1.01, 1.02, and so on. If linear light coding is
used, the “delta” of 0.01 must be maintained all the way up the scale to
white. This requires about 9,900 codes, or about fourteen bits per compo-
nent.
If you use nonlinear coding, then the 1.01 “delta” required at the black
end of the scale applies as a ratio, not an absolute increment, and
progresses like compound interest up to white. This results in about 460
codes, or about nine bits per component. Eight bits, nonlinearly coded
according to Rec. 709, is sufficient for broadcast-quality digital television
at a contrast ratio of about 50:1.
If poor viewing conditions or poor display quality restrict the cont
Title: Re: 16bit printing...your thoughts?
Post by: Bart_van_der_Wolf on May 03, 2011, 05:06:07 pm
I believe that paper can (at best) do a 100:1 contrast, and that 8 bit using ideal gamma encoding is in principle enough for that range to avoid visible banding.[

However, there are practical deviations from my idealised case.

Indeed. Do not forget that the image data has yet to undergo a conversion from the document's colorspace to the output modality's colorspace. That can be a perfect oppostunity to introduce posterization in smooth gradients.

Cheers,
Bart
Title: Re: 16bit printing...your thoughts?
Post by: alain on May 03, 2011, 05:17:22 pm
Indeed. Do not forget that the image data has yet to undergo a conversion from the document's colorspace to the output modality's colorspace. That can be a perfect oppostunity to introduce posterization in smooth gradients.

Cheers,
Bart

Hi Bart

Doesn't that normally happen inside print software going van 16 bit (if the image is 16bit) and only at the last moment converting to 8-bit and then sending that to the printer?
Title: Re: 16bit printing...your thoughts?
Post by: deanwork on May 03, 2011, 05:59:35 pm
So the Canon 16 bit plug in is pretty much a wasted effort in most cases?

john
Title: Re: 16bit printing...your thoughts?
Post by: Scott Martin on May 03, 2011, 06:03:16 pm
So the Canon 16 bit plug in is pretty much a wasted effort in most cases?

No, the printing plug-in has tons of other benefits. If you're printing from Photoshop anyway, the plug-in and it's streamlined workflow, is the way to go.
Title: Re: 16bit printing...your thoughts?
Post by: deanwork on May 03, 2011, 06:25:41 pm
Scott,

I know the plug in is great and avoids a lot of problems, I was referring to the 16 bit capability.

j
Title: Re: 16bit printing...your thoughts?
Post by: Scott Martin on May 03, 2011, 06:30:01 pm
I know the plug in is great and avoids a lot of problems, I was referring to the 16 bit capability.

Well like I said above you can see slight differences but they are just that - very slight. Modern drivers also support a 16 bit path so the Canon PS plug-in isn't the only 16bit party in town anymore.
Title: Re: 16bit printing...your thoughts?
Post by: Bart_van_der_Wolf on May 03, 2011, 06:35:05 pm
Hi Bart

Doesn't that normally happen inside print software going van 16 bit (if the image is 16bit) and only at the last moment converting to 8-bit and then sending that to the printer?

Hi Alain,

Presumably, yes. One can only hope for the sensible thing being done, first a colorspace conversion then followed by a rounding down to 8-b/ch data in case of an 8-b/ch pipeline. However, when starting with an 8-bit/channel source that is an opportunity lost. The only thing left to somewhat mask the potential posterization is clever dithering or adding noise.

Cheers,
Bart
Title: Re: 16bit printing...your thoughts?
Post by: hjulenissen on May 04, 2011, 02:08:55 am
Hi Alain,

Presumably, yes. One can only hope for the sensible thing being done, first a colorspace conversion then followed by a rounding down to 8-b/ch data in case of an 8-b/ch pipeline. However, when starting with an 8-bit/channel source that is an opportunity lost. The only thing left to somewhat mask the potential posterization is clever dithering or adding noise.

Cheers,
Bart
Slightly philosophical here:
The final image could be thought of as 1-bit (when doing B&W): either a piece of paper is covered in ink, or it is not. Perhaps in reality it is >1 due to combination of ink etc, but my point still stands that the final print covers a minimal range between maximum black and maximum white.

What you call "clever dithering and adding noise" is therefore needed, as the spatial resolution is very high, while the tonal resolution is low. By encoding any given 8-bit pixel as a number of ink/no ink "pixels" on paper, the viewer will get the impression of smooth tonality.

Since spatial/tonal resolution is decoupled this way, it makes me wonder if matching some exact dpi-setting or bit-depth for printing from photoshop should really be needed in an ideal world. In the real world, driver and hardware manufacturers make choices that are less than ideal, of course :-)

-h
Title: Re: 16bit printing...your thoughts?
Post by: madmanchan on May 04, 2011, 10:58:24 am
Generally I recommend keeping the image in 16-bit through the entire workflow that is in your hands. For example, if printing from PS, print from the 16-bit document. That means PS will perform the color xform from the document space to the output space (via the ICC printer color profile) with >= 16-bit precision. If the final output stage requires 8 bits, then PS can drop the processed image down to 8 bits (with dither). LR also does this.
Title: Re: 16bit printing...your thoughts?
Post by: Doombrain on May 05, 2011, 07:41:04 am
Epson large format only support 16bit in Mac OSX, however as DD says there's very little benifit in 16bit printing at the moment
Title: Re: 16bit printing...your thoughts?
Post by: Scott Martin on May 05, 2011, 08:20:54 am
Epson large format only support 16bit in Mac OSX, however as DD says there's very little benifit in 16bit printing at the moment

Doombrain, see my post on the previous page. Canon is the only one admits to having high bit depth data processing on their printers, and their printers do, in fact, show some benefit. While many drivers are now capable of sending 16 data to the printer, there's some debate about what other printers are capable of processing that data at a high bit depths. RGB to 8-12 color conversions and dithering takes place on the printer itself (not the driver on your computer). To do all of this on the fly at 8 vs higher bit depths requires serious computational power and cost.
Title: Re: 16bit printing...your thoughts?
Post by: nemophoto on May 05, 2011, 11:17:26 am
Ditto on the comments about the Canon iPF printers. They do implement 16-bit printing well. However, in my experience, it's mostly seen when you have a very long, subtle tonal graduation (large expanse of sky) and especially for B&W. Otherwise, I find there are times the 8-bit driver is just as effective. I know this doesn't help you much with your Epson dilemma, but I don't think Epson has truly implemented 16-bit printing the way Canon has. Therefore, I don't think you'll see a lot of difference.

As for the Mac vs. PC debate, don't let yourself be complacent. Mac Malware is out there and expanding. Up to now, PCs were the target because there are so many of them in use -- bigger bang for the buck. But with more Macs being sold, it's a larger target audience (ditto for iOS). Here's an interesting blog from ZDNET: New MAC OS X scareware (http://www.zdnet.com/blog/security/new-mac-os-x-scareware-delivered-through-blackhat-seo/8614).

Personally, I use PCs. A lot more bang for the buck. My wife, with 25-yrs as a graphic designer, has used Macs for years and is having a tough time ponying up $3500 for a new computer that I could buy/build as a PC for her for about 1/2 the cost. And honestly, once you work in InDesign, Photoshop, etc., there's basically no difference. And let's face it, how much time do you REALLY spend with an operating system (yes, it's the underpinnings). However, since we share an office, I know my wife has at least 2 or 3 program crashes or system lockups A DAY. A lot more than I have with Win 7  x64.

My 2-cents.

Nemo
Title: Re: 16bit printing...your thoughts?
Post by: Sven W on May 05, 2011, 02:41:26 pm
Canon is the only one admits to having high bit depth data processing on their printers, and their printers do, in fact, show some benefit.

I think it was back 2002 ImagePrint introduced a true 16 bit pipeline.
I still use IP on four Epson LFP and always tries to work and print everything in 16.

/Sven
Title: Re: 16bit printing...your thoughts?
Post by: Doombrain on May 09, 2011, 08:29:14 am
Doombrain, see my post on the previous page. Canon is the only one admits to having high bit depth data processing on their printers, and their printers do, in fact, show some benefit. While many drivers are now capable of sending 16 data to the printer, there's some debate about what other printers are capable of processing that data at a high bit depths. RGB to 8-12 color conversions and dithering takes place on the printer itself (not the driver on your computer). To do all of this on the fly at 8 vs higher bit depths requires serious computational power and cost.

Thanks.

Epson printers have no processing on the printer itself apart from some basic RGB rendering. all rastering is done via s/w on the PC/Mac. As it stands >OS10.5 supports 16bit with Epson drivers and a few RIPs on Windows.

while there's improvement on gradations for proof work, there's little benefit in photo/art work IMO
Title: Re: 16bit printing...your thoughts?
Post by: Scott Martin on May 09, 2011, 09:39:30 am
Epson printers have no processing on the printer itself apart from some basic RGB rendering. all rastering is done via s/w on the PC/Mac.

All printers do a fair amount of on-board processing. The printer drivers send RGB data and the on-board processing does the RGB to 8-12 "N" color conversion along with the screening/dithering rendering (the final rastering within these N color channels). The conversions and dithering are major intellectual property that they want to hold close to their chests so to speak. In some rare cases, OEMs have signed agreements with RIP manufactures to share that processing which can speed up the process. Without that onboard processing RIPs have a lot more work to do and send far more data to the printer.
Title: Re: 16bit printing...your thoughts?
Post by: digitaldog on May 09, 2011, 02:34:38 pm
I tested the 16-bit vs. 8-bit differences for my iPF6300 in two ways:

1. Printed a custom 1728 patch target built in i1Profiler in 8bit and 16bit (driver set in both cases for highest quality). Measured and compared the deltaE differences using ColorThink Pro (the results surprised me):

dE Report

Number of Samples: 1728

Delta-E Formula dE2000

Overall - (1728 colors)
--------------------------------------------------
Average dE:   0.28
    Max dE:   3.30
    Min dE:   0.01
 StdDev dE:   0.36

Best 90% - (1554 colors)
--------------------------------------------------
Average dE:   0.18
    Max dE:   0.58
    Min dE:   0.01
 StdDev dE:   0.12

Worst 10% - (174 colors)
--------------------------------------------------
Average dE:   1.14
    Max dE:   3.30
    Min dE:   0.59
 StdDev dE:   0.55

--------------------------------------------------

All the high delta’s were in greens*! I think this illustrates that you may need to send the appropriate bit depth out target and image wise. Anyone else see anything like this?
*162.3   255.0   46.4   

2. Printed a very difficult synthetic image in both 8-bit and 16-bit: Bill Atkinson’s 28 balls test image. The color space was Adobe RGB (1998) and again, the driver was set for highest quality for both documents. Note also that Dither was turned OFF in Color Settings.

Results: I can see a difference, the 16-bit output has smoother graduations in many areas of the various balls. You need to look closely but its quite visible. This is a greater difference than I’ve seen in the past using the Epson driver set both ways. If you have a high bit file, you’d certainly want to pass it to the Canon export module and set it for highest quality (16-bit).
Title: Re: 16bit printing...your thoughts?
Post by: Scott Martin on May 09, 2011, 02:47:24 pm
Results: I can see a difference, the 16-bit output has smoother graduations in many areas of the various balls. You need to look closely but its quite visible. This is a greater difference than I’ve seen in the past using the Epson driver set both ways. If you have a high bit file, you’d certainly want to pass it to the Canon export module and set it for highest quality (16-bit).

Yes, that's exactly what I've been seeing from my tests since these printers first came out (2006?). I've been profiling them using true 16 bit targets since the beginning for that very reason. Good to hear your feedback!
Title: Re: 16bit printing...your thoughts?
Post by: digitaldog on May 09, 2011, 02:58:18 pm
I've been profiling them using true 16 bit targets since the beginning for that very reason.

And yet the targets out of i1P are not 16-bit although I did convert em.
Title: Re: 16bit printing...your thoughts?
Post by: Scott Martin on May 09, 2011, 03:00:24 pm
And yet the targets out of i1P are not 16-bit although I did convert em.

Seems like converting them from 8 to 16 wouldn't help much. I've actually painstakingly made my own 16 bit targets in Photoshop using true 16bit values for each and every color patch. I've also made my own reference files that contain true 16 it data.
Title: Re: 16bit printing...your thoughts?
Post by: digitaldog on May 09, 2011, 03:04:45 pm
Seems like converting them from 8 to 16 wouldn't help much. I've actually painstakingly made my own 16 bit targets in Photoshop using true 16bit values for each and every color patch. I've also made my own reference files that contain true 16 it data.

There’s either a difference in how the driver handles the data or the data itself. I suppose I could try to subtract them in Photoshop and see (again, Dither is off). Photoshop doesn’t make this easy when the two doc’s are different bit depths.

So do we need to get X-Rite to export 16-bit data? I can’t imagine why its not the default anyway. Then the next question would be, would they do that and how darn long would it take them?
Title: Re: 16bit printing...your thoughts?
Post by: Scott Martin on May 09, 2011, 03:09:16 pm
So do we need to get X-Rite to export 16-bit data?

Yes, I think so! I vote for full 16 bit support for both for target generation and for measurement data and processing.

Then the next question would be, would they do that and how darn long would it take them?

Oh man, I'm not going to touch that one, LOL!
Title: Re: 16bit printing...your thoughts?
Post by: digitaldog on May 09, 2011, 03:13:45 pm
OK, I asked in the proper channel for this so it seems reasonable we should see it any day now... Oh sorry, major brain fart.
Title: Re: 16bit printing...your thoughts?
Post by: Schewe on May 09, 2011, 07:25:59 pm
I've actually painstakingly made my own 16 bit targets in Photoshop using true 16bit values for each and every color patch. I've also made my own reference files that contain true 16 it data.

Well, if you were using Photoshop then the target file ain't a full 16-bit. They are 15+1 bit targets since Photoshop doesn't do full 16-bit files...PS will only deal with 0-32,768 for a total of 32,769 levels in Photoshop...not 16-bit.
Title: Re: 16bit printing...your thoughts?
Post by: digitaldog on May 09, 2011, 07:49:47 pm
Well, if you were using Photoshop then the target file ain't a full 16-bit. They are 15+1 bit targets since Photoshop doesn't do full 16-bit files...PS will only deal with 0-32,768 for a total of 32,769 levels in Photoshop...not 16-bit.

Further, I tried sampling a target up and down a number of times in Photoshop and comparing to the original. Using Apply Image>Subtract, the results appear to show no difference which kind of makes sense. I have dither off. The patches are solid colors. I’m not certain having the package save out the colors values in high bit would bring anything to the party but I’m open for suggestions in further testing.

Now there clearly is a difference in terms of what the target produces from a Spectrophotometer when 8-bit vs. 16-bit data is sent to the driver. But it doesn’t appear to be based on the target itself, at least as far as I can see with the limited testing I’ve done.
Title: Re: 16bit printing...your thoughts?
Post by: Schewe on May 09, 2011, 11:04:45 pm
Further, I tried sampling a target up and down a number of times in Photoshop and comparing to the original. Using Apply Image>Subtract, the results appear to show no difference which kind of makes sense. I have dither off. The patches are solid colors. I’m not certain having the package save out the colors values in high bit would bring anything to the party but I’m open for suggestions in further testing.

As long as you have dither turned off, I wouldn't expect to seem much difference. However, you could clearly spec different color targets if you were starting from within PS using high bit-depth color specifications.
Title: Re: 16bit printing...your thoughts?
Post by: JeffKohn on May 09, 2011, 11:14:00 pm
Quote
Now there clearly is a difference in terms of what the target produces from a Spectrophotometer when 8-bit vs. 16-bit data is sent to the driver. But it doesn’t appear to be based on the target itself, at least as far as I can see with the limited testing I’ve done.
I don't think 16-bit test targets would be of any benefit. First, unless your test targets have more patches than can be represented in 8-bit color, what is the point? Second, even if you did create such a target, I'm not sure our spectro's are accurate enough to register such minute differences reliably. Trying to measure so many closely-spaced data points could actually hurt profile smoothness. I've seen this when creating monochrome profiles using QuadToneRIP's  QTR-Create-ICC. I got smoother results by averaging multiple 21-step charts than I did by 1 (or mulitple averaged) 51-step charts.

Title: Re: 16bit printing...your thoughts?
Post by: Scott Martin on May 09, 2011, 11:25:07 pm
Quote
They are 15+1 bit targets since Photoshop doesn't do full 16-bit files...

I'm going to miss that little piggy!!! Yes, I understand.

Further, I tried sampling a target up and down a number of times in Photoshop and comparing to the original. Using Apply Image>Subtract, the results appear to show no difference which kind of makes sense. I have dither off. The patches are solid colors. I’m not certain having the package save out the colors values in high bit would bring anything to the party but I’m open for suggestions in further testing.

Another test is needed. Try this: Take a BA 16 bit target. It's a true 16 bit file. Which means that a middle grey could 127.5 not just 127 or 128 - there are lots of increments in between 8 bit integers! :-] Take this 16 bit BA file and convert it to 8 bits and back to 16. Do your subtraction comparison (there are at least two ways of doing this - I personally like to have two layers with the top blending mode set to "subtract") and look at the numbers.

Do the numbers all show "0"? Well, think again! Click on the eyedropper in the info palette and switch it to show you 16 bit values (which are really 15 bit 0-32,768 values as Schewe brought up). There *are* differences - just differences so small that a crude 8 bit scale doesn't illustrate. Thus is the delicate nature of 16 bit imaging!

So, being a geek, I like to make custom made 16/15 bit (let's just call them "high bit depth") profiling targets and use them with corresponding high bit depth references files. Just like Bill (gotta give credit where credit is due). Tear apart my ColorPort XML files and you'll see numbers like Red=255.501 Green=127.533 Blue=33.434 instead of Red=255 Green=128 Blue=33. ColorPort's reference files also contain measurements to the third decimal.

True high bit depth profiling hand-in-hand with true high bit depth output seems a wonderful thing. I enjoy it, regardless of how small the benefit may be. :-]

Title: Re: 16bit printing...your thoughts?
Post by: Scott Martin on May 09, 2011, 11:53:19 pm
Even if you did create such a target, I'm not sure our spectro's are accurate enough to register such minute differences reliably.

Oh sure they do. ColorPort saves measurements down to the thousandth of a integer (like 127.583 instead of just 127). Working at this level of accuracy is what Bill Atkinson's targets were all about right?

Trying to measure so many closely-spaced data points could actually hurt profile smoothness. I've seen this when creating monochrome profiles using QuadToneRIP's  QTR-Create-ICC. I got smoother results by averaging multiple 21-step charts than I did by 1 (or mulitple averaged) 51-step charts.

I prefer the QTR 21 step chart as well. But we're not really talking about increasing the *number* of data points are we? We're talking about the *accuracy* of the data points we've got - even if it's just 21 patches. Rounding the data up or down for each patch (via 8 bit values) could potentially be harmful. Your 21 patch results are even better when they (target and measurements) are at high bit depth.

To take your idea a bit further, I'm really excited that i1Profiler produces excellent results with a relatively small number of patches. And I'll suggest that the results are a little better when those small number of patches are at high bit depth. I'll suggest that a high bit depth 800 patch chart yields better results than a 3000+ patch 8 bit target. Follow me on this? Checkout my RGB targets at http://www.on-sight.com/downloads/ if you like.



Title: Re: 16bit printing...your thoughts?
Post by: hjulenissen on May 10, 2011, 01:24:56 am
Oh sure they do. ColorPort saves measurements down to the thousandth of a integer (like 127.583 instead of just 127). Working at this level of accuracy is what Bill Atkinson's targets were all about right?
But does it contain useful information in those decimals?

If you take any 8-bit number (e.g. "42") and add 1/3, it will need lots of bits to be represented (at least using decimal representation): 42.3333333333... but does it contain any more information than "42"?

-h
Title: Re: 16bit printing...your thoughts?
Post by: Scott Martin on May 10, 2011, 09:15:17 am
It is more information and it is useful. How much exactly is up for debate. The returns are super minor if any. Still, it's fun to strive for perfection.
Title: Re: 16bit printing...your thoughts?
Post by: Mark D Segal on May 10, 2011, 09:22:11 am
I think the whole chain of inkjet printing has reached a level of maturity such that henceforward, save for any absolutely unanticipated quantum leap forward in materials technology or software, gains of visible quality are likely to be bit-by-bit. But over time, these little bits accumulate, such that after a few years, looking back, one would see improvement. In this regard, it's good to stay on top of the little bits as they accrue, even though they seem "little" at the time.
Title: Re: 16bit printing...your thoughts?
Post by: JeffKohn on May 10, 2011, 11:43:40 am
Oh sure they do. ColorPort saves measurements down to the thousandth of a integer (like 127.583 instead of just 127). Working at this level of accuracy is what Bill Atkinson's targets were all about right?
But read a chart multiple times and you won't get exactly the same values for each patch. My argument is that you would actually be better off duplicating an 8-bit value and averaging the readings, rather than having patch values of 127.583 and 127.852 and assuming the difference you measure is precise enough to be useful data.

Quote
I prefer the QTR 21 step chart as well. But we're not really talking about increasing the *number* of data points are we? We're talking about the *accuracy* of the data points we've got - even if it's just 21 patches. Rounding the data up or down for each patch (via 8 bit values) could potentially be harmful. Your 21 patch results are even better when they (target and measurements) are at high bit depth.
No, we're talking about synthetic charts here, not real-world photos where a 16-bit capture loses data when converted to 8-bit. As long as the 127,127,127 patch really is 127.000, 127.000, 127.000, it's perfectly accurately represented in 8-bit color. It's just as accurate as a 16-bit patch with a value of 127.333, 127.333, 127.333. There's no data loss from 8-bit here because the chart values are exact 8-bit values to start with. That's what I mean with my original statement about chart size. If you're going to measure 3000 patches out of billions of potential values, there's no reason not to choose the values that happen to be exact 8-bit values.
Title: Re: 16bit printing...your thoughts?
Post by: digitaldog on May 10, 2011, 12:09:58 pm
I’m not sure there is much to gain between a true 16-bit produced target and one that’s 8-bits per color. None the less, the engines that build these targets can (and I would suggest should) feed us 16-bit TIFFs as we can convert to 8-bit per color but going the other way, not so sure. I can’t believe its big engineering for X-Rite to spit out a 16-bit TIFF. I don’t see any downsides.

Could take Bill’s 16-bit target, print, measure and compare to the same target converted to 8-bits per color. But in the end, the delta’s would probably be differences we expect to see with multiple measurements of the same target. And I’d agree, its probably a lot better to just sample a number of targets and build the profile, certainly for some devices (presses).
Title: Re: 16bit printing...your thoughts?
Post by: hjulenissen on May 10, 2011, 02:05:27 pm
It is more information and it is useful. How much exactly is up for debate. The returns are super minor if any. Still, it's fun to strive for perfection.
Adding 1/3 to a number does not add information. If you think that the number of stored bits indicate more information, then you are simply wrong.

Now, if you think that those bits does add information, you need to present some other argument than the number of bits stored.

-k
Title: Re: 16bit printing...your thoughts?
Post by: Mark D Segal on May 10, 2011, 02:09:26 pm
If I understand this correctly, I believe at the very least it adds precision to the calculations. And if you have more distinguishable finite levels, is this not "adding information"?
Title: Re: 16bit printing...your thoughts?
Post by: JeffKohn on May 10, 2011, 02:52:50 pm
If I understand this correctly, I believe at the very least it adds precision to the calculations.
What calculations? We're talking about a test-chart, not the measurements or actual profile profile generation.

Quote
And if you have more distinguishable finite levels, is this not "adding information"?
No. If you are printing a target with 3,000 patches, whether you take those samples out of 16 million possible values or several billion doesn't determine the accuracy of the values selected.

You guys don't seem to understand precision versus accuracy. You're arguing that a 16-bit value is more accurate than an 8-bit value for all color values. That's true for 16-bit color values that fall in-between the possible 8-bit values; but for the 16million colors that can be exactly represented as 8-bit values, that just isn't true.
Title: Re: 16bit printing...your thoughts?
Post by: Scott Martin on May 10, 2011, 03:05:53 pm
But read a chart multiple times and you won't get exactly the same values for each patch.

Sure, this is an issue of *tolerance* isn't it? At what digit do we see variations? If we always saw variations at the first digit ofter the decimal then I'd agree the additional digits aren't helpful. However, I'm finding that the measurement variations occur (with my instruments) at the second and third digits after the decimal. From this I'd conclude that the additional information, particularly the first digit after the decimal, is valuable extra precision/information. Your results may vary especially if you're using a device with looser tolerances, like an EyeOne Pro.

My argument is that you would actually be better off.....

Have you tested your argument or is it just theory? Have you compared repeated 16bit measurements from true 16bit targets?

No, we're talking about synthetic charts here, not real-world photos where a 16-bit capture loses data when converted to 8-bit.

When we ask i1Profiler to render profiling target patches it can either render them at 16 bits with greater precision or round the numbers to an 8 bit scale. In a manner of speaking, one might say that prior to rendering the targets, the reference colors *are* at a high bit depth. So your analogy to a 16 bit capture workflow is intact with this comparison along with the potential benefits.

There's no data loss from 8-bit here because the chart values are exact 8-bit values to start with.

That's incorrect. Make a set of patches in i1P and save them as a patch set file. Open the txt file at look at the RGB sample numbers - they *are* recorded at a high bit depth with multiple digits after the decimal! 8 bit targets are rounded and bastardized versions of these colors.

I think it's fair to say true 16bit targets and measurements and reference files offer greater precision. What's harder to quantify is how much benefit there is to using them. When I compared Canon's 16bit output with 8 and 16 bit profiling in Monaco Profiler I actually saw slightly smoother results with the 16 bit profiles. I need to repeat this test in i1Profiler - with their smoothing the benefits could be negligible if any. Either way I'm starting to think I'm the only person with a true 16 bit profiling workflow that's capable of showing any potential benefits...

Quote from: Andrew Rodney
I’d agree, its probably a lot better to just sample a number of targets and build the profile.
Probably? Don't assume - test it! I've tested and seen benefits in the past, allbeit small. My demanding clients that have used lots of other profiling services say they are crazy happy with these 16 bit profiles. Let's talk real world results - not theory.
Title: Re: 16bit printing...your thoughts?
Post by: Alan Goldhammer on May 10, 2011, 03:53:57 pm
I’m not sure there is much to gain between a true 16-bit produced target and one that’s 8-bits per color. None the less, the engines that build these targets can (and I would suggest should) feed us 16-bit TIFFs as we can convert to 8-bit per color but going the other way, not so sure. I can’t believe its big engineering for X-Rite to spit out a 16-bit TIFF. I don’t see any downsides.

Could take Bill’s 16-bit target, print, measure and compare to the same target converted to 8-bits per color. But in the end, the delta’s would probably be differences we expect to see with multiple measurements of the same target. And I’d agree, its probably a lot better to just sample a number of targets and build the profile, certainly for some devices (presses).
The one way to do the experiment is to use ArgyllCMS where you do have the choice between 8 and 16 bit targets (along with a lot of other options).
Title: Re: 16bit printing...your thoughts?
Post by: Scott Martin on May 10, 2011, 03:57:10 pm
The one way to do the experiment is to use ArgyllCMS where you do have the choice between 8 and 16 bit targets (along with a lot of other options).

Do you mean to say that's 'one way of doing the experiment', or that's 'the one and only way of doing it'?
Title: Re: 16bit printing...your thoughts?
Post by: Alan Goldhammer on May 10, 2011, 04:17:02 pm
Do you mean to say that's 'one way of doing the experiment', or that's 'the one and only way of doing it'?
Former and not the latter.  I only have access to Argyll as it is free to use; other tools may prove useful as well but cost money.   I'm waiting on an i1 to arrive so I can really start building some Argyll profiles (been using a ColorMunki to date which works but I've been concerned that it's a UV cut spectro (and also not built to the same tolerance as an i1 - I hope) and I'm going to miss something in papers that might have mild OBAs such as Ilford GFS and Hahnmuhle Photo Rag Ultra Smooth).  To date the CM Argyll profiles are quite good.
Title: Re: 16bit printing...your thoughts?
Post by: Passnga on May 10, 2011, 04:58:33 pm
Without reading through the entire thread, and rereading your first question regarding printing, I believe, and Farmer or Jeff Shewe may correct me here, Epson printers are still only working in 8bit. Not that that means you should work in 16bit but rather that the printers themselves are only 8bit.
I would work in 16bit as far processing and working on images but that doesn't mean the printer prints in 16bit. I could be wrong though...
Title: Re: 16bit printing...your thoughts?
Post by: Mark D Segal on May 10, 2011, 05:15:30 pm
What calculations? We're talking about a test-chart, not the measurements or actual profile profile generation.
No. If you are printing a target with 3,000 patches, whether you take those samples out of 16 million possible values or several billion doesn't determine the accuracy of the values selected.

You guys don't seem to understand precision versus accuracy. You're arguing that a 16-bit value is more accurate than an 8-bit value for all color values. That's true for 16-bit color values that fall in-between the possible 8-bit values; but for the 16million colors that can be exactly represented as 8-bit values, that just isn't true.

Yes I know we are talking about a chart. The chart is a printed image file. Each patch represents file numbers. Those numbers will be read by a spectro and the differences between the readings and the file numbers determine the translations the CMS will need to make for colour managing the printer. So it would seem logical to me that the precision/accuracy of the target print would influence the calculations of the profile generated with it and from there the calculations in the CMS. I agree with your last sentence; it makes sense, but are we sure that all the patches in a target represent true 8-bit values?
Title: Re: 16bit printing...your thoughts?
Post by: alain on May 10, 2011, 05:33:58 pm
...
That's incorrect. Make a set of patches in i1P and save them as a patch set file. Open the txt file at look at the RGB sample numbers - they *are* recorded at a high bit depth with multiple digits after the decimal! 8 bit targets are rounded and bastardized versions of these colors.
...

This seems and an explanation and a rather stupid error inside i1P.  The software knows it's generating 8-bit data, but stores them as a different RGB number inside the patch set file.  So when generating the patch set file it's already wrong.

When the software knows that the generated value is for example 70,120,130  (8-bit max) and stores it with reference 70.5,120.3,130.4 ...  I hope that they do the other calculations a bit more correct. 
Title: Re: 16bit printing...your thoughts?
Post by: hjulenissen on May 10, 2011, 05:35:58 pm
Yes I know we are talking about a chart. The chart is a printed image file. Each patch represents file numbers. Those numbers will be read by a spectro and the differences between the readings and the file numbers determine the translations the CMS will need to make for colour managing the printer. So it would seem logical to me that the precision/accuracy of the target print would influence the calculations of the profile generated with it and from there the calculations in the CMS. I agree with your last sentence; it makes sense, but are we sure that all the patches in a target represent true 8-bit values?
I think that it is difficult to say anything conclusive without detailed knowledge of each component in the pipeline.

My objection was with claims ala "16 bits must give more precision than 8 bits". Clearly, that is not a valid claim. If the spectrometer or anything else along the chain is limited by analog noise, A/D or D/A conversion, digital processing precision or elsewhere to a precision similar to 8 bits or below, the benefit from doing 16 bits anywhere may be small or none.

This can most easily be seen by doing a digital conversion from 8 bit representation to 16 bit representation. The latter will consume twice the amount of storage/bandwidth, but will add no information.

-h
Title: Re: 16bit printing...your thoughts?
Post by: hjulenissen on May 10, 2011, 05:41:53 pm
Sure, this is an issue of *tolerance* isn't it? At what digit do we see variations? If we always saw variations at the first digit ofter the decimal then I'd agree the additional digits aren't helpful. However, I'm finding that the measurement variations occur (with my instruments) at the second and third digits after the decimal. From this I'd conclude that the additional information, particularly the first digit after the decimal, is valuable extra precision/information. Your results may vary especially if you're using a device with looser tolerances, like an EyeOne Pro.
Then you seem to assume that errors have to be random (noise). A systematic error (like adding a constant, or quantizing to 8 bits) may give series of measurements that have (near) identical values without this variance being a good indicator of the absolute precision.

-h
Title: Re: 16bit printing...your thoughts?
Post by: Alan Goldhammer on May 10, 2011, 06:58:21 pm
It's little bit like arguing how many angels can dance on the head of a pin.  Once can pick the simplest of test charts to print out so that reading is easy.  You can read the patches and see if there is a measurable difference, but we need to know where the weak link is in the chain.  I suspect it will be the spectro in regards to its precision and it's differential repeatability.  If you have a value of 200.0007 but the instrument is capable of only reading to 1/100 of a unit the extra data you have is meaningless.  Similarly if your relative difference in readings is .05, you can be assured that your value of 200 is reasonably certain.  Now I can create an ArgyllCMS profile and run the profcheck utility and get a direct read on every one of the 980 patches that I've read, with the relative error, the RGB value, and LAB values and the difference in the LAB values and what they should be.  When I examine the data in Excel I see readouts of 7 significant figures; I doubt that my ColorMunki has this kind of precision (I know from some early testing that its variance between duplicate readings is roughly 0.25% which is probably pretty good for an instrument in this price range).  So we are left with the question of 8 or 16 bits for targets (and I run an Epson on Win7 so my prints are in 8 bits).
Title: Re: 16bit printing...your thoughts?
Post by: digitaldog on May 10, 2011, 08:04:25 pm
What calculations? We're talking about a test-chart, not the measurements or actual profile profile generation.

Well there is a reference file that defines the expected values. So its not really fair to say that its just a test chart. One would assume the reference of the chart has the same degree of precision as the measurement data.
Title: Re: 16bit printing...your thoughts?
Post by: hjulenissen on May 11, 2011, 03:47:49 am
Similarly if your relative difference in readings is .05, you can be assured that your value of 200 is reasonably certain.
Except if the spectrometer (or the patches) have a constant error.  Knowing the tolerances compared to a golden reference tells us more than simply observing the sample-variance.

If the "true" value is 200.42, then one instrument may measure [200 201 200 200 201], another may measure [200.99 200.98 200.99 200.98]. Which is most accurate?

-h
Title: Re: 16bit printing...your thoughts?
Post by: Shane Webster on May 11, 2011, 10:02:23 am
Quote
Well there is a reference file that defines the expected values. So its not really fair to say that its just a test chart. One would assume the reference of the chart has the same degree of precision as the measurement data.

How precise is it when the pxf file generated by i1P truncates values.  Does this represent 8-bit information that i1P relies on when creating its profile.  If the same patch set is exported as a CGATs file for use with MT, the values are carried to the hundreth decimal place.  Would this then be 16-bit information that PMP relies on when creating its profile.  Having different values for the same item does not seem overly precise (regardless of its real world perceptibility).

In ColorThink, I compared testcharts created from i1P to testcharts created from MT based on non-truncated values and the values were the same for each.  It appears then that both MT and i1P create 8-bit TIFFs.  The is also seen in ColorLab.  I can take the patch set (shows decimals), convert to an image and then back to spot colors and the values are truncated.  Comparing this roundtrip to the original patch set generates an average Delta E of .46, maximum of 1.6, best 90% of .4 and worst 10% of 1.01.  If I've done my comparisons correctly (which may be a big if), it appears both MT and i1P generate testcharts with truncated values and, since the XML files generated by i1P contain truncated information, i1P compares measurement files of those truncated testcharts to truncated patch set information.  This may perhaps then lead to differences within MT because it is reading a chart based on truncated values to a patch set containing decimal values, but, as a property professor of mine long ago stated to our class, I may be meandering through the enchanted forest.   
Title: Re: 16bit printing...your thoughts?
Post by: digitaldog on May 11, 2011, 11:06:48 am
How precise is it when the pxf file generated by i1P truncates values.  Does this represent 8-bit information that i1P relies on when creating its profile. 
Since the TIFF is 8-bits per color, I’d assume the reference is as well. And its kind of moot based on the data the TIFF is composed of.
Quote
It appears then that both MT and i1P create 8-bit TIFFs.
They do indeed.
Title: Re: 16bit printing...your thoughts?
Post by: Shane Webster on May 11, 2011, 11:18:46 am
Quote
Since the TIFF is 8-bits per color, I’d assume the reference is as well

But it's not.  Opening the reference file in MT of the TIFF it created yields a first patch value of 109.3, 221.0, and 17.0.  Opening the TIFF yields values of 109.0, 221.0 and 17.0.
Title: Re: 16bit printing...your thoughts?
Post by: Mark D Segal on May 11, 2011, 11:22:15 am
But it's not.  Opening the reference file in MT of the TIFF it created yields a first patch value of 109.3, 221.0, and 17.0.  Opening the TIFF yields values of 109.0, 221.0 and 17.0.

Does anyone reading this thread have an operational insight into the practical difference it makes to outcomes whether the first patch reads 109.0 or 109.3? This is a serious question, not a critique of the observation or of the fact that it was measured.
Title: Re: 16bit printing...your thoughts?
Post by: digitaldog on May 11, 2011, 11:27:52 am
But it's not.  Opening the reference file in MT of the TIFF it created yields a first patch value of 109.3, 221.0, and 17.0.  Opening the TIFF yields values of 109.0, 221.0 and 17.0.

I wouldn’t assume that just because you have data after that decimal point its defining 16-bit data of what is obviously an 8-bit per color TIFF. Only X-Rite could tell us and I’d wonder why then they do not save out a high bit TIFF.
Title: Re: 16bit printing...your thoughts?
Post by: Shane Webster on May 11, 2011, 11:48:17 am
Quote
Does anyone reading this thread have an operational insight into the practical difference it makes to outcomes whether the first patch reads 109.0 or 109.3?

I agree and it's is a question I've been curious about for the last week or so when I first noticed it.  The only thing I can tell you is when I compare the truncated TIFF values in ColorLab with the original values, the maximum Delta E is 1.6, with the worst 10% having a Delta E of 1.01, which means the differences would be perceptible to some (though probably only if they were looking).  I brought it up on this thread because the discussion became one of precision and having different values in different files when those files may or may not be used when creating a profile doesn't seem to be overly "precise" to me, regardless of its practical difference (though, ultimately, I realize it's the practical difference the matters). 

Quote
Only X-Rite could tell us and I’d wonder why then they do not save out a high bit TIFF.

Somehow I don't think that's going to happen anytime soon, but it would be nice if we were surprised.  Since I looked at the TIFF, I don't think it does make a difference in i1P.  Its XML data is truncated and the TIFF is 8-bit.  The difference could be in MT and PMP where if it's using the data exported from i1P, the reference would be 16-bit but the TIFF would be 8-bit, which would seem to lead to some erroneous colors, though, as Mark asks, I don't know the practical application of it or even if MT uses the 16-bit numbers or whether it truncates the values when creating a profile.
Title: Re: 16bit printing...your thoughts?
Post by: JeffKohn on May 11, 2011, 12:04:03 pm
Quote
That's incorrect. Make a set of patches in i1P and save them as a patch set file. Open the txt file at look at the RGB sample numbers - they *are* recorded at a high bit depth with multiple digits after the decimal! 8 bit targets are rounded and bastardized versions of these colors.
Well, this just further confirms my low opinion of the XRite/GMB programmers. But it doesn't prove that 16-bit TIFF's are needed for optimal profile quality, it just proves that the reference files are wrong. There's no reason that makes any sense for writing values in the reference file that don't exactly match the corresponding TIFF file, this can only be considered a bug.

So while I remain convinced that 16-bit profile targets are unnecessary, I'm glad this issue came up. Now I know that I need to correct my reference files before I do my next profile.
Title: Re: 16bit printing...your thoughts?
Post by: Alan Goldhammer on May 11, 2011, 12:57:51 pm
Does anyone reading this thread have an operational insight into the practical difference it makes to outcomes whether the first patch reads 109.0 or 109.3? This is a serious question, not a critique of the observation or of the fact that it was measured.
This is the $64 (US) question that begs an answer.  Many years ago when I was still a bench biochemist I had a project that involved a lot of spectroscopy and we highly concerned about the precision of the instruments that we were using.  One had service contracts on every single one of them since going out of spec would have grave consequences for the experimental results.  I'm pretty sure that the same type of QA/QC is not built into i1 (much less ColorMunkis) that X-Rite sells.  Now you can get the specification for the i1 here (http://www.xrite.com/product_overview.aspx?ID=1461&Action=Specifications).  What you don't know is whether the deviation is constant throughout the spectral range of interest.  The short term repeatability appears to be quite good but it was only measured against white.  It might be useful to have information on 10 different patches across the spectrum.  I know from the little bit of work that I've done using ArgyllCMS and my ColorMunki that there is variability throughout the readings of the patch set.  What I don't know is how much of this is because of the paper I am profiling, how much is from the instrument, and finally how much might be from the printer driver's interpretation of the color that is being sent to it.

If one wanted to look at the ArgyllCMS algorithm the code is available for downloading.  The difficulty in all of this is that we are probably too worried about the precision of an instrument that probably cannot read to as many significant figures as our computers and software can handle.  It's very difficult to judge between the scientific precision of the instrument/profile making process and the outcome regarding the standard errors of the readings and the subsequent visual proof.  There are tools out there that can give one an insight into specific patch color and reliability of reading but the bottom line in all of this is to insure that there are no major gaps in the profile, that the gamut volume appears to be reasonable for the printer in question and finally that a well known test print (either one that is commonly used or one that you as a photographer have taken and know what is pleasing about it) can be reliably printed.  I think in the end this is what we can hope for.
Title: Re: 16bit printing...your thoughts?
Post by: Trey on May 29, 2011, 07:44:27 pm
I would make two comments about using 16bit printer. One is that once teaching a class, I printed a 4' by 17" print consisting of two white to black transitions as a demonstration of the difference of bit depth vs resolution. And a four foot 256 step grad right next to a four foot 65000 step grad is quite visibly astounding. This may not transfer into a real world advantage though, I am not sure.

The other point is that I tend to do a lot of photoshop work before I print and editing in 16bit files hardly ever get bashed very badly, as do the 8bit files. The histograms are usually smooth with no holes or spikes.

16bit files are a huge resource hog though. Some operations the take a few seconds in 8bit might take a minute or even more in 16bit. Saving the files is a pain also, although I have heard Adobe released a registry change that helps the files save, I believe, in 1/20 the time.

But as far as sending 8 or 16 bits to the printer, I am not sure I have noticed too much difference.