Color, Color Management, Settings and Work Flow

[Roger Clark]

Many of us here on BPN calibrate out monitors, but what specific settings do you maintain throughout your workflow from start to finish?

First some background. I believe I understand in detail the theory behind color management. As a scientist, I do imaging spectroscopy, both measuring the reflectance of different materials, computing reflectance, and computing different instrument responses (the eye is "just" another instrument), as well as creating color output for various devises (from monitors to print). Most of this I do from my own software. Where I get confused is when I need to use other software that is not adequately documented (or maybe I haven't found the right documentation) and so is just a "black box" to me, e.g. photoshop. Then add confusion where the operating system may be doing something with color management and may be fighting other programs (like photoshop) in the background.

Background for people new to color management, see the links in this thread:
http://www.birdphotographers.net/forums/showthread.php/84347-Color-Management-Tutorial

Let me first describe my color settings/workflow.

Calibration with Spyder 3 for gamma 2.2, white point= 6500 K (using Argyll in linux).
In linux: do:
system -> Preferences -> Color Profiles and select the profile to use to each monitor.

Camera: in raw conversion I output a 16-bit tif Abobe RGB image (e.g. with ACR).

In photoshop, open the image and photoshop recognises the adobe rgb color space.
This is the source color space.

But what are the correct settings in photoshop? It seems that one should be using the monitor profile and using:
view -> proof setup -> monitor RGB
and
view -> proof colors (checked).

This sets up photoshop to use the monitor profile correctly. But what if the operating system is already managing the colors with the monitor ICC profile? When I had a windows machine (I still do have a windows laptop) it seemed the colors in photoshop were never quite correct.

For example, download the color calibration test photos here:
http://www.gballard.net/photoshop/pdi_download/
and load the adobe RGB and sRGB images into photoshop and into firefox (or other color managed browser). On a correctly configured system, the four images should look virtually identical in color managed programs like photoshop and firefox. Do they for you?

Check your color-managed web browser and examine the images on this web page (these are the same images as for the above downloads):
http://www.gballard.net/psd/go_live_page_profile/embeddedJPEGprofiles.html
The first image on the upper left is adobe RGB and when you mouse over it, it is sRGB. In firefox on my linux machine, the two images appear pretty identical, as they are supposed to. Note they should appear identical whether or not your system is calibrated. This is also independent of whether or not the colors are accurate on your monitor, and assumes the gamut of your monitor is adequate to render the colors in the image correctly.

On my system, I get consistent and expected response from firefox, but NOT from photoshop. I can easily toggle on and off linux's color management (something I was never sure of in windows) and the photoshop relative differences are similar though there is a brightness and color shift..

Here is what I observe in photoshop:

Proof setup = monitor RGB, proof colors on: adobe rgb image looks like that in firefox but different than sRGB image (sRGB image is redder and more vibrant). The sRGB image in frefox looks like the adobe RGB image in firefox and the adobe RGB image in photoshop.

Proof colors off: adobe RGB and sRGB look closer in photoshop, and more like the sRGB image above (proof colors on), but the abobe RGB image in photoshop does not match what is seen in firefox.

Does anyone observe similar situations and/or can explain what is going on?

it seems to me that the correct settings should be:
view -> proof setup -> monitor RGB'
and
view -> proof colors (checked).

But I find it frustrating in photoshop that many operations result in turning off proof colors. So I can be editing and find my proof colors have been turned off. Is there a way to keep this on until I want to change it?

Roger

[Mike Milicia]

I believe this recent email from "Ask Tim Grey" will at least partly address your questions.
Bottom line is that you should not be using "View -> Proof Setup -> Monitor RGB" for image editing.

http://myemail.constantcontact.com/Ask-Tim-Grey---Soft-Proofing-for-Display---May-24--2011.html?soid=1103416365862&aid=2ZzVnPDLEX4

[Roger Clark]

I believe this recent email from "Ask Tim Grey" will at least partly address your questions.
Bottom line is that you should not be using "View -> Proof Setup -> Monitor RGB" for image editing.

http://myemail.constantcontact.com/Ask-Tim-Grey---Soft-Proofing-for-Display---May-24--2011.html?soid=1103416365862&aid=2ZzVnPDLEX4

Interesting.

I found in Frazer, Murphy, and Bunting, Real World Color Management, 2nd edition, 2005, page 217, it says to choose proof setup: Monitor RGB.

Roger

[Mike Milicia]

Hi Roger,

I do not have that book and I am by no means a color management guru but my understanding is that "Proof Colors" on with "View->Proof Setup->Monitor RGB" will display the image as it would appear if the RGB values in the image file were simply put out to your monitor with no color management of any kind. You will see major color shifts when you do this unless the image file is already in a color space which closely matches the native monitor, e.g. sRGB. In general, "Proof Colors" is a way to simulate what the image would look like on various output devices. For general image editing, you want the display to reflect the colors represented in the image's color space. Photoshop's color management does this by default using the image's current profile to determine the color that is represented by a given RGB value in the file and then consulting the active monitor profile to determine what the monitor needs to be given to have it accurately display that color. With "Proof Colors" on, Photoshop will instead display what the image would like if it were converted to the specified profile (without actually converting the file's RGB values). So, unless you are optimizing for a specific output device, "Proof Colors" should be off.

Hopefully, someone else who understands all of this better than I do will chime in and can also comment on the recommendation made in the "Real World Color Management" book.

[Roger Clark]

OK, I got it solved!

I said in my original post that I could see consistency in programs like firefox, but not photoshop. That was not quite correct. The problem is that the reference images I was using from the web site
http://www.gballard.net/psd/go_live_page_profile/embeddedJPEGprofiles.html
did not give COMPLETE consistency. And I was not quite sure which appearance was correct. The key was loading 3 images: the sRGB, Adobe RGB and Pro Photo RGB images. I loaded all of them into photoshop, into firefox, and into the windows 7 image and fax viewer, which are all color managed. All three images in all the color managed programs should show the same colors. Further, in the web site above, there is a panel called:
"FULL COLOR MANAGEMENT" (Value 1) in Firefox 3.6x
where if you mouse over the image, the colors should remain the same. On my system, they were not. Further, while I had some consistency within a program and some between programs, it was not COMPLETE consistency.

As a result, I would observe things like color shifts when I converted from Adobe RGB to sRGB. I have seen others complain of such color shifts here on BPN. Or say they see a color shift between images on their system and after posting on BPN. If you observe any such color shift, something is not set correctly! There should be no color shifts, It is true that in conversion from aRGB to sRGB, some colors are clipped, but perceptually this should, and in general, does not cause a visible color shift. I tested several images where I previously observed color shifts in conversion to sRGB, and retested them and now see NO color shifts.

Now this problem of color shifts occured on my windows XP system and on my new linux + virtualbox + windows 7 + photoshop system (seems like asking for trouble, but linux has given me the tools to understand and diagnose the problem).

My solution. (even if you are not using linux, if you have color shift issues, read on).

1) Color calibrate with a Spyder 3. I calibrated under linux using Argyll (very impressive). Argyll makes an ICC profile which in linux is easy to apply at the system level.

2) Apply the monitor profile:
Ubuntu:
System -> Preferences -> Color Profiles
select icc profile generated from argyll (the dispcal program)

3) CHECK that the calibration is correct. For example, go to
http://www.normankoren.com/makingfineprints1A.html
and about half way down the page is an image for checking gamma. It should be 2.2 (mac may be 1.8, but there is controversy about whether is should be 1.8). Anyway, I calibrated to 2.2 but when tested, found it was about 2.7!. Recalibrate and test again. I had to do several tries eventually telling Argyll to calibrate to gamma 1.7 and white point 6500 K.

Once I had a verified calibration, the 3 test images were much closer, but still varied depending on settings in different programs.

One would think that if the ICC monitor profile was set at the system level, that other programs would be using the system, so get the colors correct. NOT! For example, in firefox, enter (as the URL): about:config and look at gfx.color_management.display_profile. By default, it is set to blank, meaning use the system profile. Well it sort of was, but for some reason I can't explain, it was not complete. On the gballard.net web site above, in the "FULL COLOR MANAGEMENT" (Value 1) in Firefox 3.6x section, I did not observe with firefox the behavior described. I had changed gfx.color_management.mode to 1 (default is 2), but that did not help. What I had to do was load the full path to the monitor ICC profile, e.g.:
gfx.color_management.display_profile /home/profiles/del30inch-may25_2011.icc
(Note, above is a linux path, windows will be something like C:\profiles\mymonitor.icc)
Once I did this, I finally had complete consistency within firefox on the gballard.net web page and when loading the test images from the web site into firefox. Note: I left gfx.color_management.rendering_intent at 0.

Now to photoshop.

edit -> color settings ....
custom
Adobe RGB (1998)

View -> proof colors unchecked.

With proof colors checked, I do not have complete consistency. So now I see, with proof colors unchecked, the same colors between all test images in photoshop, as well as firefox, windows 7 image and fax viewer, and gimp (gimp and firefox under linux). And when I go to my images I've posted on BPN, I see the same colors as my images in photoshop (viewing BPN with firefox or seamonkey).

In the next couple of weeks, I'll do this on a window 7 system.

So if you are seeing any color shifts between Adobe RGB and sRGB, and postings on BPN, your colors settings are not correct.

Roger

[Roger Clark]

Hi Roger,

I do not have that book and I am by no means a color management guru but my understanding is that "Proof Colors" on with "View->Proof Setup->Monitor RGB" will display the image as it would appear if the RGB values in the image file were simply put out to your monitor with no color management of any kind. You will see major color shifts when you do this unless the image file is already in a color space which closely matches the native monitor, e.g. sRGB. In general, "Proof Colors" is a way to simulate what the image would look like on various output devices. For general image editing, you want the display to reflect the colors represented in the image's color space. Photoshop's color management does this by default using the image's current profile to determine the color that is represented by a given RGB value in the file and then consulting the active monitor profile to determine what the monitor needs to be given to have it accurately display that color. With "Proof Colors" on, Photoshop will instead display what the image would like if it were converted to the specified profile (without actually converting the file's RGB values). So, unless you are optimizing for a specific output device, "Proof Colors" should be off.

Hopefully, someone else who understands all of this better than I do will chime in and can also comment on the recommendation made in the "Real World Color Management" book.

Hi Mike,

What you describe is what I observe, so I think you are correct. It is a little strange though, as color management is supposed to manage the colors to produce a consistent color on each selected device, whether it be printer A or printer XYZ. So why then if one chooses the monitor as the output device, it turns off color management? Seems like it should treat the monitor as the output device and make the colors consistent. Does not seem logical to me. But that is exactly what I observe now that I have everything correct. So Tim Grey is correct (I also have his book on color management): view -> proof colors unchecked is the way to go. Thanks for posting the Tim Grey link as that lead me to more research that solved my problems. Now it makes the Frazer et al tip more confusing.

Roger