Didn't you look at the caption this picture thread?
It's all the dogs fault.
Reminder don't use a dog to spray the screen in the future.
Of course some of the other junk could be building up on the screen, certainly hate the stuff that builds up on polycarb headlights and turns them yellow. PIA to clean (most it's the remembering to do it that's hard).
Here are a few things:
1.) Check you color sync profile.
2.) Load in a blank white picture and move it around the screen.
Are there really hot spots.
3.) Load in or create a b/w test 4 square test pattern. Do the same.
4.) Try these resolution test patterns. SMPTE and BWH test patterns to download.
5.) Are you a smoker, or is the screen in direct sunlight for a time?
Spotty yellowing may occur behind an in front of the screen from smoke and nicotine. Sunlight may damage a screen with UV.
If you find "hot spots" and have AppleCare, give Apple a call.
6.) If your dog does pee on the screen, it should just drip off. If it doesnt, you dog may be diabetic. Glucose in the urine will cause it to stick.
I hope my advice helps diagnose the problem.
And I hope others chime in.
Sorry about the recent batch of Puckish humor.
I deal with tech problems all the time.
I'm just a little worn. I just had somebody nuke an amp. With a sweaty unwaxed paper cup. I not getting any audio and my cup has a hole it.
The truth about dog pee is true. A good early indicator that your you dog is diabetic is a line of ants visiting their slightly syrupy pee. Some other signs are here!
I'm looking for some more links on LCD and backlight yellowing. I havent experienced yellowing LCDs, and I work with a few dozen. I have experienced color skewing and pixel failures, but not yellowing.
anyway, the issue is real.
the screen sits away from windows and the sun.
i don't smoke.
there's no dog.
the areas that are yellow tinged follow the edges of the screen and best i can figure, it's the pixels burning out in a weird way, or (less likely in my view) dustparticles inside the glass that's making it discolored.
Im assuming that its an Apple LCD
If not what make is your LCD?
How old is it?
It sounds like dust and oxide are creeping in, perhaps from improper sealing of any of the multiple lamintes that comprise an LCD screen.
If it has a cold cathode tube I cant see the reason for only the outer edges to yellow. If the light pipe is oxygen sensitive, it might account for it yellowing around the edges.
EL backing also ages uniformly, but most LCDs dont use this technology.
If you or anybody else has ever taken the screen apart, you might have improperly put it back together. Perhaps the screen is pressing to tightly against the frame. This would cause tweening of the matrix and bending of the light pipe, and ether one could account for a localized spectral shift.
I am just throwing out ideas to see what people think.