This is just the scanner showing you what's there -- the paper around the letters probably is a little darker. Adjust the scanner settings to increase the contrast. Come to that, if you're scanning at 600dpi, you can probably get better results scanning in black and white, not greyscale (except for images, of course). 1-bit sample attached.
Originally Posted by scanner
I scan at1 TIF 600dpi at greyscale in my scanner OpticBook 3600
as you can see in this screenshot, the scanner somehow produces images with some marks, I don't know if glossy paper is responsible for this (the marks look like reflections) or the scanner or something else