Calibrating Your Scanner?

[DougC]

- - - I am trying to scan a line drawing that uses black and dark green, and even though the two colors appear different to the eye, the scanner mottles each with lots of the other. I can clean it up by hand but would rather not have to.
- I decided to test my printer/scanner. I created and printed out a test sheet with Paint Shop Pro. The test sheet has sample areas of color in pure red, green and blue, as well as black and the 0:2:2 and 1:2:2 combinations of red, green and blue.
- Not one scanned in correctly. I can understand that they might not hit the same exact color, but the scanned areas should at least be consistent and none were. For the color 255,0,0, the scanned sample contained several colors around 220,45,45 and there was no way I could find in PSP to correct the problem. It seems the scanner software has 256 colors available, and seeks to use every damned one of them, if you want it to or not. I could adjust the palette in PSP, but the colors are not only in the red areas (in this case) but scattered in other areas as well.
- Is there any way in PSP to set a palette and then scan (or filter, I guess) an image, "forcing" it into the pre-set palette? That is, if you know an image is only a four-color image and you scan it in, you should only get four colors. I'm guessing that to prevent the errors they'd have to be caught by the scanner software. Are there any that do this?

[Padeye]

I don't think you're going to get the color precision you want from a consumer scanner.

As for making the dark green and black distinct I'd try playing with the brightness and contrast on the scan to get those colors in the middle of the tone scale rather than dark as they really appear. You'll put the important colors in the linear part of the scanner's response cuve rather than near the limit.

[astro]

IIRC I think the scanner palette (on most scanners anyway) is controlled primarily by the twain scanner driver and most have color depth and resolution settings there. Unless you can get your hands on a better quality scanner your problem may be difficult to solve via software.

Once the image is scanned you can force a color depth change via most editing software but I don't think this really will solve your impure color issue as trying to force a reduced pallette onto an inherently muddy color is a frustrating process at best with respect to getting quality results.