Early users of iPhone4 have reported issues with the iPhone Display, the iPhone’s much discussed Retina Display has been noticed with a yellow discolored area either as a thin line or as a circular tint .

After fiddling with the display settings users confirmed it as a screen defect, many users have reported it to Macrumors with negative reviews, Gizmodo is also getting a flood of complaints regarding the issues from its readers.
One of the discussions started by the victim says
“Just synced up my iPhone 4 and noticed that, on screens with a white background (i.e., Settings.), there is a decidedly yellow spot on the lower left corner of my screen. It appears circular (about the size of a pencil eraser) but when you rotate the phone sideways, it’s more visible as running across the bottom edge of the screen a ways. Anyone else? Also, assuming I wait til the weekend to make a Genius Bar appointment (to avoid the Thursday crush at the store), is Apple likely to have replacement phones on hand this early in the launch? “
On requesting pictures from the user he replied
“Well, it doesn’t show up in screenshots since the defect appears to be in the output screen and (I assume), the screenshot really just snaps the data as presented to the screen. I think I’d need to use an external camera to capture it and, though it is noticeable, I’m not positive a camera would capture it. I guess I’ll wait a couple of days to see if “burn-in” or some similar concept will address it. But, you know, one I saw it, I can’t UNsee it.”
Apple has dealt with a similar problem in its 27” iMacs , possible cause of the problem is still unknown neither the intensity of the problem is known .
Apple has offered to replace the iphone4 , but when a user rushed to a Apple retail store he was told there are no replacement units available at the moment , it may take some time until affected users receive a replacement .
