Originally Posted by Blossom
It doesn't matter what temp my Kindle is I use it 5 to 8 hours a day. The contrast never changes.
Thin fonts are a known problem, because of the way that kindles use gray pixels for antialiasing the fonts. The antialiasing algorithm was designed for light-emitting displays, and does not work well for passive displays like eInk. Additionally, changing an isolated pixel using an electric field slightly affects neighboring pixels (which is what causes ghosting on gray pixels). The problem is that eInk displays work best with pure black and white pixels forming the core lines and curves of font characters, which is WHY you need a bold font, to ensure that no part of the character is "gray-only". As you can see here, thin fonts have some portions that do not contain black pixels:
The top font in the image is a "standard" kindle antialiased font. The bottom one has enhanced contrast that works better on an eInk display. This is especially noticable in poorly lighted conditions, or when the eInk is operating outside its optimal environmental conditions.
The problem as shown is not with the hardware, but is instead a software problem (incorrect font rendering algorithm). This software problem is especially noticable with thin fonts that were antialiased for light-emitting displays used on eInk, when the correct thing to do would have been to use pure black and white antialiasing with pixel dispersion as is used on older laser printers.
Because this is a SOFTWARE problem, the comparison results also depend on which software versions are installed in the two kindles. A software upgrade may install a font with higher contrast.
Of course, every individual display unit is slightly different (even from the same batch), which is why they contain calibration data in a ROM on the flex cable. It is possible that your unit was not tuned correctly, or was not at the correct temperature when it was tuned. Perhaps a batch of units is statistically sampled and the whole batch uses the same tuning parameters.
Not knowing what procedure is used when calibrating these displays at the factory, it is possible that some kindles either were not tuned correctly, or deviate too far from others in the batch to look good with a "typical" set of tuning parameters (IF that is how they are done).
Perhaps somebody at amazon or lab126 can enlighten us on why *some* kindles may have inferior quality compared to others (if they have been tested properly).