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Author Topic: ProPhotoRGB  (Read 18665 times)
paulbk
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« Reply #100 on: August 05, 2005, 03:42:50 PM »
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Rodney,
Don’t delete the RAW keepers. I often go back and reedit my original RAW capture as the technology improves as well as my skill. And since my skill is two clicks from none, I have lots to look forward to..

Why should any one edit using colors they can not print, today?
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paul b. kramarchyk
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PeterLange
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« Reply #101 on: August 06, 2005, 02:05:47 AM »
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First, with rendering intents to output spaces, you have to decide if you’ll clip the colors or compress them. ...
Just a friendly question:
 
Are there any printer profiles
which support Perceptual rendering in way
which assumes that the source space was ProPhotoRGB?

Peter

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No. Output profiles don’t have any idea when built what the source color space will be.
 

Doesn’t the profiling software implement the Perceptual intent
and its non-linear transforms
based on a on a silent assumption about the source color range?

Peter

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Hermie
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« Reply #102 on: August 07, 2005, 12:18:24 PM »
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The main parameters for calibrating a monitor are the white point, black point and gamma. Once these are set, profiling is done to measure the numerical differences between the (correct) data describing the color reference patches of the profiling software and the (perhaps incorrect) values the monitor shows them as. These measurements are then used to create a profile that neutralizes these differences so the monitor shows the colors of the file data. Likewise the printer profile measures and neutralizes differences between the (correct) data in the software file for each patch on the profiling target and the (perhaps incorrect) numerical values the printer prints them at. (Both sets of profiles calculate interpolations for all the data between these reference points.)
A bit OT but, generally this works just a bit different, it does NOT measure the numerical differences between the (correct) data describing the color reference patches of the profiling software and the (perhaps incorrect) values the monitor shows them as

Generally monitors/printers are fed with input signals (just numbers without any perceptual meaning, e.g. RGB(255,0,0). Remember you have to turn off color management when sending patches to a printer, it's all about the numbers. The devices response to these input signals is measured in device-independent (or colorimetric) color coordinates and is used to create the forward (A2B) table and inverse (B2A) table (computational step) or matrix.

Herman
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PeterLange
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« Reply #103 on: August 08, 2005, 05:32:58 PM »
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Peter - fine, the same thing with added detail, but so what? The bottom line is that anyone claiming a significant downside to working in Prophoto color space needs to demonstrate in normal photographic prints that rendering intents have a differentially negative impact on posterization as you move from smaller to larger embedded or working color spaces relative to the (fixed size) output color space. It is not clear in principle and where is the practical real-life evidence?
Mark,

Now after we have talked about RelCol (posterization / channel clipping), please have a second look at my initial posts at page 7.  Just give it a chance. I have no marketing mission to argue someone into anything.

Cheers! Peter

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digitaldog
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« Reply #104 on: August 09, 2005, 12:19:38 PM »
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Andrew, thanks - now we're getting down to where the rubber hits the road. Is it correct to infer from your reply that one should NOT USUALLY see in a print, for example, increased posterization because of the fact that ProPhoto has more "invisible colors" at play than ARGB98?
Depends on a number of factors. The Synthetic image shows you things you can’t see on real world images or might show up if you just happened to have an image that had color and tone that contained problematic areas. You might never see the issues unless you got lucky (or unlucky). On the other hand, the synthetic image is only useful in showing some things. For example, going to the Dan Margulius “test” rules for evaluating the usefulness of 8 versus 16-bit, a synthetic image is a no/no. However, such an image might very well show the effect of quantization errors. Yes, you may never see this show up in a real image but the errors are still there. That’s somewhat useful. It may not be “real world” but it does provide a wealth of information.

ProPhoto has non visible colors! To make the size it needs to be, the primary colors had to be stretched to the point the blue primary falls off the CIE chromaticity diagram!
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Andrew Rodney
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bossanova808
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« Reply #105 on: August 17, 2005, 12:46:43 AM »
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The point was only that Andrew mis-read the article, perhaps didn't read it, and claimed there is a fundamental mis-understanding of colour spaces in the quote - which there isn't.

You're just re-stating the point - that it is the gap between tones, and what those tones mean (ie how the numbers are tied to concrete colours), that changes in a colour space, NOT the total number of tones.

What inferences should be drawn from said point is up to you.

That's all!  I certainly wasn't taking on the whole thread - I'd rather be doing some real work!
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Hermie
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« Reply #106 on: August 04, 2005, 01:26:42 AM »
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paulbk wrote: Bottom Line: Being able to "see colors on a monitor" is self-deceit if your intention is to make a print. And for me, it is ALL about the print.

and by using ProPhoto RGB you are actually using your printer's full gamut. I agree with Mark saying that "printers can reproduce certain hues that are within the ProPhoto gamut but outside the Adobe RGB98 gamut. By using the wider gamut you don't run the risk of losing hues that the printer can handle."

See e.g. this graph that'll show the relationship between camera, monitor, printer and working spaces:
http://www.xs4all.nl/~teeuwen/ColorThink%20Graph.jpg
It's all about the small triangle on top of the Artisan profile:
Adobe RGB clips some camera colors, especially dark greens/yellows that you see frequently in foliage. Although your monitor cannot show these colors, the Epson R800 for example can print them.

Herman
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Mark D Segal
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« Reply #107 on: August 05, 2005, 09:07:12 AM »
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Suppose one day you change printers, get one with a different and wider color gamut and you want to make better prints of some older files - you would need to have had the benefit of the additional information. As well, you can visualize data loss within PS before printing by soft-proofing with your printer profile in the soft-proof set-up, allowing you to make last-minute adjustments if you don't like what you see.
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Mark D Segal (formerly MarkDS)
Author: "Scanning Workflows with SilverFast 8....." http://www.luminous-landscape.com/reviews/film/scanning_workflows_with_silverfast_8.shtml
digitaldog
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« Reply #108 on: August 05, 2005, 03:49:40 PM »
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Rodney,
Don’t delete the RAW keepers. I often go back and reedit my original RAW capture as the technology improves as well as my skill.

Why should any one edit using colors they can not print, today?
Delete them, never. In fact my big decision today is do I want to fully embed the original RAW in my .DNG’s or not. Bigger file and I have a lot more confidence in .DNG but it’s hard to get past the idea of throwing away the actual original data.

However, once I process my RAW data into a wide gamut, high bit archive, I really don’t want to go back to the RAW/DNG unless there’s a gun to my head. Yes, as RAW converters get better so can the rendered data. But I’d rather if possible go to the actual image data (the rendered and encoded file in ProPhoto) and work from that. I’ll do capture sharpening, clean up whatever needs to be done and consider that my “transparency” to use for all subsequent uses. I can go back to the “Negative” and make a “new print” so to speak but I’d rather not.

By starting the process by going into a wider gamut working space, there are fewer reasons I’d go back to the RAW.

There may be colors today I can use but that device may not be sitting on my desktop. I don’t own a LightJet (as well as a lot of really nice output devices) and it’s possible I might want a print in a week that has a wider gamut than what I have on my desktop. It’s not like I have to way 5 years.
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Andrew Rodney
Author “Color Management for Photographers”
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paulbk
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« Reply #109 on: August 05, 2005, 11:22:32 PM »
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>Well, unless you have a new Adobe RGB display, you're STILL not "seeing" everything in the image, what's your point?

You don’t improve anything by adding more unknowns.

>Actually, testing has indicated that there is potentially a Delta E of up to 2+- even sending the same file to the exact same printer/paper combo, even on the same day. There's built in variability (read chaos) in most anything...

From a practical point of view I agree there’s variability in the mechanical performance. That’s a manufacturing QA issue. Not much we can do about it except keep the nozzles clean and aligned etc. I’m talking about the digital process. Send the same file to a printer and the printer receives the same set of ones and zeros in exactly the same sequence. The nozzles fire in exactly the same sequence. Etc. You get the same print within the manufacturing/repeatability tolerance of the printer.

>have no idea what you are talking about. . .wanna take another whack at it?

A)  Make a 1 inch square filled with ProPhoto SATURATED red, R=255, G=0, B=0.
  Send it to the printer using relative rendering intent. It probably doesn’t matter.
C)  You get a 1 inch square of saturated print space red. Not (A) above.
D)  Make a 1 inch square filled with ProPhoto ALMOST saturated red, R=254, G=0, B=0.
E)  You get a 1 inch square of saturated print space red. Not (D) above.
F)  Make a 1 inch square filled with ProPhoto NEARLY saturated red, R=253, G=0, B=0.
G)  You get a 1 inch square of saturated print space red. Not (F) above.

Now you’ve sent three different files to the printer and you got the same print each time. And this series is almost endless. You are going through motions in the belief your efforts will have some real effect. When in fact they will not. I call that a religious experience.
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paul b. kramarchyk
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Mark D Segal
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« Reply #110 on: August 07, 2005, 12:37:22 PM »
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Herman, yes that is a more precise description of what I was getting at.

Peter Lange: further to my previous post I should have mentioned one could also adopt a workflow whereby one insures all colors are in gamut by having the gamut warning turned on (this only works properly with soft proofing set-up) and adjusting everything so nothing is "greyed out" (if grey is the color selected to illustrate out of gamut stuff). However - the point relevant to this thread is that this procedure does not become any more or less useful as a function of the chosen color space.
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Mark D Segal (formerly MarkDS)
Author: "Scanning Workflows with SilverFast 8....." http://www.luminous-landscape.com/reviews/film/scanning_workflows_with_silverfast_8.shtml
Hermie
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« Reply #111 on: August 08, 2005, 12:20:41 PM »
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You might want to try this on a synthetically constructed image like a Granger Rainbow.
you can download a Granger Rainbow from:

http://www.colorremedies.com/realworldcolor/downloads.html
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Mark D Segal
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« Reply #112 on: August 09, 2005, 12:07:29 PM »
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Andrew, thanks - now we're getting down to where the rubber hits the road. Is it correct to infer from your reply that one should NOT USUALLY see in a print, for example, increased posterization because of the fact that ProPhoto has more "invisible colors" at play than ARGB98?
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Mark D Segal (formerly MarkDS)
Author: "Scanning Workflows with SilverFast 8....." http://www.luminous-landscape.com/reviews/film/scanning_workflows_with_silverfast_8.shtml
Hermie
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« Reply #113 on: August 17, 2005, 01:31:28 AM »
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The point was only that Andrew mis-read the article, perhaps didn't read it, and claimed there is a fundamental mis-understanding of colour spaces in the quote - which there isn't.

You're just re-stating the point - that it is the gap between tones, and what those tones mean (ie how the numbers are tied to concrete colours), that changes in a colour space, NOT the total number of tones.

What inferences should be drawn from said point is up to you.

That's all!  I certainly wasn't taking on the whole thread - I'd rather be doing some real work!
There IS a fundamental misunderstanding in Daalder's quote:
"All colour spaces of the same bit depth (typically 8 or 16 bit) have the same total number of tones. That is, a bigger colour space does not mean there are more colours in total!"

A bigger space DOES mean more colors.
A color space doesn't have a bit depth! It's the image that has a bit depth. So the following statement is true: An image with a given bit depth has the same number of tones, regardless of the color space it's in.

Herman
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Mark D Segal
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« Reply #114 on: August 04, 2005, 08:59:20 AM »
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Thanks for the reference to the Jeremy Daalder article which I read with interest. But I am not convinced. Firstly, I work in 16 bit mode, so anything that can happen in 8 bit mode is of no concern. Secondly, I have been using ProPhoto for months with a variety of photos, some with deep shadow areas, and I have observed ZERO banding of anything anywhere in the printed output. I look upon using ProPhoto as an insurance policy. Just in case there are some ProPhoto hues - say deep yellows or magentas - that my 4000 can print - I haven't sacrificed them by confining myself to AdobeRGB98. This might not sound as scientific as the Daalder article, but I think it makes practical sense.
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Mark D Segal (formerly MarkDS)
Author: "Scanning Workflows with SilverFast 8....." http://www.luminous-landscape.com/reviews/film/scanning_workflows_with_silverfast_8.shtml
digitaldog
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« Reply #115 on: August 05, 2005, 12:02:25 PM »
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Correct me  if I'm wrong, and I think that this is what Paul has been saying all along. If my prints are made on a Fuji Frontier which prints to the sRGB colour space, then does it not make more sense to work in that colour space  from the beginning of my workflow so that I am not assuming certain saturated colours are contained in ACR using prophoto and then converting to the print colour space of sRGB just before sending to print, losing the saturated detail and having to start again.
The Frontier does not, repeat does not print to sRGB. It assumes all files are in sRGB to convert to it’s output color space.\

There’s only one output device on the planet that output’s sRGB. That’s a display that fully follows the specifications (down to the ambient light in which the display resides) of sRGB.
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Andrew Rodney
Author “Color Management for Photographers”
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PeterLange
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« Reply #116 on: August 05, 2005, 04:23:17 PM »
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First, with rendering intents to output spaces, you have to decide if you’ll clip the colors or compress them. ...
Just a friendly question:

Are there any printer profiles
which support Perceptual rendering in way
which assumes that the source space was ProPhotoRGB?

Peter

--
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Schewe
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« Reply #117 on: August 05, 2005, 10:34:09 PM »
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Aside: “using Soft Proofing correctly, you can be about 90% accurate in your visual predictions on-screen to print.”
As I said, using a large color space puts the fun and intrigue back in printing.

Well, unless you have a new Adobe RGB display, you're STILL not "seeing" everything in the image, what's your point?

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Seen from a different point of view: If you send the same file to the printer you get the same print every time.

ding, sorry, thank's for playing our game...

Actually, testing has indicated that there is potentially a Delta E of up to 2+- even sending the same file to the exact same printer/paper combo, even on the same day. There's built in variability (read chaos) in most anything...

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Even if half the pixels are out of print space gamut. The print process is deterministic going one way. But the reverse is not true. If you could run time backwards and feed the same print into the printer you will not get the same file every time. Because there is only one in gamut file and many many out of gamut files that will render to the same print.

I have no idea what you are talking about. . .wanna take another whack at it?
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Schewe
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« Reply #118 on: August 06, 2005, 09:09:31 PM »
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Any “best practice” how to proceed?
Yes, use Photoshop's softproofing to see what the heck the image will look like when printed, pick the best rendering intent for the image and under softproofing, adjust the image to achieve the results you want.

It really isn't all that hard folks...a lot of what has been talked about here is really pointless-what matters is what the heck does the image look like when reproduced in its final form-and that all comes down to learning how to softproof. If you have a 90% accurate prediction, on screen, of the dynamic range and color of the final print, anybody with "decent" Photoshop tone and color adjustment skills can learn to nail the final output if not on the first print (which to be honest is about where I am "most" of the time) or with one single iteration.

Also, just to be absolutely clear-it doesn't matter a bit to an output profile, what the incomming color is...profiles go from the interchange space (usually but not always Lab) to the output space via a rendering intent. Whether the original data is comming from sRGB, A RGB or PP RGB doesn't matter one bit. What DOES matter and matter a lot is the quality of the output profile in terms of the interchange to printer side as well as the interchange to display side. Many profiles can be used to do a decent job of transforming from the working space to the printer space but the reverse tables suck and those profiles are useless for softproofing.
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Schewe
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« Reply #119 on: August 07, 2005, 02:11:15 PM »
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The problem with the Out of Gamut Warning is that while it tells you what colors are in/out of gamut, it doesn't tell you by how much. It only indicates that it's out. Also, it doesn't tell you how the resulting out of gamut clip/compression will effect you image.

Out of Gamut Warning is a much older tool in Photoshop than the softproofing function. As such, Out of Gamut is pretty old tech. The real way to deal with out of gamut colors is to view them in the softproofing environment to see what visual effect will result in the clip/compression of out of gamut colors and allow YOU to choose how to handle it.
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