No need to be. No two screens are exactly the same. It is just like that. It's the reason why photographers and other people in the graphics industry go to great pains to calibrate and profile screens, and even buy very expensive stuff to do it (and expensive screens that take well to calibration). Read below....
This certainly is the case. You *will* get used to it.
As I said in this thread earlier, I take many pictures, and a lot of my time is spent in front of color calibrated and profiled LCD-screens. Color calibration and profiling is done using a special device and some software. This proces makes screens show the correct colors. I've even calibrated the screens I use at my workplace.
Therefore, I am used to seeing true white on LCD screens. If I look to a screen of one of my colleagues, I can *immediately* tell if the screen is off. Most are too reddish, blueish, greenish, or yellowish. On some screens, their white actually looks light red, or light blue to me.
The fun thing is: the person working with that particular screen day in day out says I am stupid and that his whites are perfectly white, not red or blue. And to him, all screens in the office are fine. His eyes are not trained to recognize perfect white, as are mine, and therefore he is unable to pick up color casts.
Until.... he does not look at the screen for some time, and I put my screen right next to his. Then that person will immediately see that his screen is off color.
So yes, you can and will get used to a color cast, eventually, assuming that you do *not* have perfect material to compare with on a regular basis. So, if you have one perfect Paperwhite, and one with blotches, or two with different color casts, and you use them interchangeably, you will not get used to the discoloration.
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Maybe I'm just in luck, but as posted earlier, my PW is perfect with regard to lighting evenness, but it does have a color cast. When used at my preferred light setting 13 in this room, the screen is a bit grayish with a tinge of a blue-green cast. See this picture.
http://members.home.nl/katsunami/mis...n/_0012041.JPG
Photoshop agrees with my assesment, as the eyedropper says:
R: 135 G: 154 B: 163
The paper is (almost) perfectly light gray under these lighting conditions:
R: 169 G: 160 B: 163
So... grayish (all values are quite comparable, and far from 255/255/255 white), but with a green-blueish cast. And when you compare it to the almost perfectly gray paper, you can easily see the color cast. Whe you do not have a real white on screen for comparison, then the paper will after some time look like a dull white, and the kindle will also start to look lighter. It's just the way your eyes work. They fool you. Easily.
The trick is: I don't have another paperwhite to compare with. When reading for some time, the screen is just a dull white. The moment I put it next to "Google", displayed on my perfectly calibrated computer screen, or beside a sheet of high quality photo paper, then it's definately grayish with a blue-green tinge.
When bringing up the level to 17-18 or so, the screen will turn bright white, but then it's too bright to comfortably read in here. Then it's going to start to look like an LCD.