I'm having the same on my new 21.5". It's not really hindering me from working with the system but since I noticed it first time, it's more and more disturbing and I'm also thinking about giving it back to Apple.
Read about in the german forums also. There are more people having this "Yellow tinge" issue.
Think its a quality issue of the panel.
Yep, the 21 inch seems to have it too.
I visited a local Mac retailer today and their demo 27" had it. Looked exactly like my iMac, even the same shape of the yellow tinted area. Sounds very much like a panel fault to me. Hopefully not all machines have it.
I hope the link works, it is an image with two grey bars. Download it, open in Preview and compare the upper and lower grey bar. On my screen the upper one looks fine but the lower one is very yellow/warm.
I talked to another Mac retailer in my town and he confirmed that their demo 27" has it too.
I will check the next batch of machines and if they also have it I must return it and go back to my previous alu 24".
OK, I called Apple this morning and they agreed to send me a new iMac to replace the one with
the yellow tinge. In the afternoon I went to a electronic store where they also have a Mac corner.
They had 4 new iMacs there (2x 21 and 2x27) and guess what - they all have the yellow tinge, so for
me this is something really serious because every panel seems to have it and I don't know how people can not recognize it.
I have at least two more reports of 27" with the yellow tint.
Now looking for a reliable report of a uniform screen. Anyone with a 27" that see the same color temperature for the upper and lower grey bar in the image I posted above?
I would be extremely disappointed if all the iMacs have this fault. It would be terrible if it is because of heat or something else that is not fixed with a new panel...
If so, I hope Apple will make a Cinema Display 27" and I will keep my 24" ATI 4850...
Same problem with two iMac 21,5" bought at "Gravis-Store" in Germany. Apple Support registered my case and told me to contact Gravis.
Gravis will call me back if there are new 21,5" iMacs for change in stock - the are sold out at the moment...
Anyway, nice to see that I´m not the only one with this problem
A pic of the screen if anyone is interested.
I have slightly adjusted saturation to better show the variations in color. It is very visible with the eye.
Lower right has some kind of strong yellow/green tint while the upper has a slightly blue/purple tint.
I just been to my apple reseller and demo models they have also has the yellow tinge. I also was telling them this problem and a few others that I have. He says they would look at it but because of the limitation in LCD screen technology, there is an acceptable amount that apple has before leaving the factory.
If I spent $1800 on this machine I would expect that it would have the best LCD screen available.
Some bad news for the weekend:
Just received my replacement iMac 27". This one is even worser than the previews one. Together
with the yellow tinge fading to the bottom it has also a vertical yellow strip (about 100 mm) right
from the center of the screen. It looks terrible if you have a grey background or if you drag a finder window across the desktop area.
Conclusion: These LED displays are terrible and not useable. Maybe the guys only watching HD Movies on there iMacs will not recognize it but that's not the application I want to use a Mac for.