I see the same thing like you do, its odd. My first scanner was an HP 6300C model used it for a very long time, still scan but much slower so I changed to Epson Perfection V500 Photo Digital ICE Technology which is what I am presently using.

Did you try scanning with lower or higher 24 bit color? How about decreasing or increasing the dpi? Try experimenting using both the "Auto Contrast" and playing around with the scan manually with the "brightness" and "contrast" and see how it goes.

The best scan chips that I have ever seen are the ones done by Greg Susong. His chip scans are pratrically perfect circle/square - Greg has a "secret" weapon and skills use behind in his "darkroom" - and the latest digital technology available in the market today. We should invite Greg Susong to give us Free Seminar in "Chip Scans and The Latest Technology" and this board will get a much better images. I am not saying that he is the only one out here, although I respect individuality of expressing individual posters chip scans.

When you get the right mix please share it here in the board or please send me an email - I believe I got plenty of room to improve my scans.

Good luck!

Leonidas