Hi, On Wed, Dec 31, 2003 at 02:16:40PM -0500, Charles Sprickman wrote: > This will hopefully be the last time I bother the list. My Umax 2200 is > now basically working, but the scans look pretty bad. They have what I > could best describe as "banding" or "smearing". An example from a 300dpi > scan is here (white areas on the left are the scanner lid and show the > pattern rather well - looks like the output of a really bad inkjet > printer): > > http://home.manymonkeys.com/out.png (approx. 1MB png)
On first sight I would have said: the image is ok. When I looked with gimp and it's magnifying option I found two effects: a) There is a small line distance correction error. That means that the colors are not exactly centered vertically. You can see that effect best at the top edge of the photo. There is a blue/brown stripe. Possible causes: Bug in the backend or scanner firmware. Or low quality scanner. b) High noise. The colors of two adjacent pixels should be (mostly) the same in the white area. Possible causes: Low quality sensor. Defective or old lamp. Bug in the backend or firmware (calibration). I guess the horizontal lines that look like an old inkjet print are cause by problem a). As I don't own such a scanner I have no clue how to solve it (if possible), however. Bye, Henning
