In the past couple of days I've had a few people contact me privately about their K4 screen having issues. It seems to me there is definitely something going on with a bad batch of K4s out there. One person has two tone text.
This is a very small percentage though compare to those happy with their K4s. I've encourage them to contact Amazon for replacements if they're not happy.
I think concerning screen contrast, the background should be a light color whether it have a gray or creme tint. It should look very light, near white when you are holding the K4 reading. The text should look black and sharp not jagged and not gray. You shouldn't be able to see the pixels on the letters because Pearl uses Anti-Aliasing.
It shouldn't matter if you're using 6 page refresh or 1 page refresh. The text should still look black, sharp and smooth, at least it does on mine. The other difference in the refresh settings I noticed is the background will start to look dirty when I do a 6 page refresh but that's normal. I've seen worst ghosting on my K3 when it's cold. It's really not that bad but I prefer a clean page each time so I use the 1 page refresh setting.
When you contact Kindle support they will ask if you have the latest firmware which is 4.0.1 so be sure to upgrade to that to see if it fixes your problems. They will also have you change the refresh settings and restart the Kindle.
I'm by means am no expert on this. I just speak from personal experience of my own Kindles. I agree that photos can be very misleading and often hard to capture what the naked eye is seeing. As someone who has worked in graphic and web design for years. I just may be picky when it comes to fonts and contrast.
