Important Hints on Color Management under Windows XP!!

Question

After struggling for several hours, I have learned a couple important tidbits I have not seen elsewhere in these forums. As much confusion as I read in here about color management and color issues, this might be quite important to some.
If you want to skip the story, jump down to the last few lines of this entry for the summary.
I recently built a new computer, and when I copied my catalog over to the new drive and opened it, all my files as viewed in Lightroom had a distinctly "yellow" tinge, as compared to their exported JPEG brethren (as viewed in Windows Explorer thumbnail view). I realized, aha, I haven't set up color management on the new system yet, so this is to be expected. Lightroom internally uses a different color space than XP, so without some color management they won't match.
Well, after going around and around setting up monitor profiles and so forth, I was getting nowhere. Nothing was changing the appearance of the yellowish images in Lightroom!
Abandoning the effort for the time being, I switched to other tasks, and imported an old catalog to see if I wanted any of the old work before I deleted it. Then i did a double take... my color problem was fixed! Could color profile info be stored with catalogs? Surely not.
So I started experimenting. Removed all monitor profiles. No change. Switched back to the newer catalog. The colors changed. Put the monitor profile back. No change. Restart Lightroom. No change. Click load catalog, and then pick the same catalog I'm on. No change. Load the old catalog, the colors changed. After several rounds of experimentation, I am now sure of the veracity of this new discovery.
Here is the moral of this story, in two bullets:
(1) Some color management changes in Windows XP are only apparent in Lightroom when you load a catalog. Even restarting Lightroom, or restarting Windows isn't enough. Only loading a catalog makes the changes show up.
(2) You can't simply reload the catalog you are on. You have to load a different catalog, so Lightroom offers to Relaunch, in order to get the changes.
I hope this helps someone.
Vaughn
http://vaughnsphotoart.com

Answer 1

>I recently built a new computer, and when I copied my catalog over to the new drive and opened it, all my files as viewed in Lightroom had a distinctly "yellow" tinge, as compared to their exported JPEG brethren (as viewed in Windows Explorer thumbnail view). I realized, aha, I haven't set up color management on the new system yet, so this is to be expected. Lightroom internally uses a different color space than XP, so without some color management they won't match.
Since Windows Explorer is not managed, they will NEVER match, even if you use sRGB in your exported jpegs as you should. This is even true if you calibrate your monitor. You can only get a complete match when your monitor's primaries correspond precisely to sRGB, which basically never happens. In unmanaged apps, calibration only impacts the contrast (i.e. gamma and blackpoint) of the monitor. This is why the use of managed apps is so important.
>So I started experimenting. Removed all monitor profiles. No change. Switched back to the newer catalog. The colors changed. Put the monitor profile back. No change. Restart Lightroom. No change. Click load catalog, and then pick the same catalog I'm on. No change. Load the old catalog, the colors changed. After several rounds of experimentation, I am now sure of the veracity of this new discovery.
This is weird. Lightroom for me always picks up on a new monitor profile after a restart. I don't need to load a different catalog. Definitely not normal and unexpected behavior.
>How could a monitor profile do this? Monitor profiles effect the image as it's sent to the monitor, so how could LR even "know" what monitor profile is selected? This still isn't making sense to me.
Actually it does have to know. The way color management is implemented on windows (and Mac OS too), is that apps are responsible for doing the translation to the monitor profile. The OS just tells the app about the monitor profile and the app can deal with it as it pleases. This way the app can either use a system library such as ColorSync or the windows equivalent, or its own profile conversion code such as all Adobe Apps do. This is why unmanaged apps are not suddenly magically corrected. The only thing that gets corrected for unmanaged apps is the grey response because this is handled by a LUT (lookup table) in the videocard.