Gerald Murray schrieb: > Quoting Pierre Willenbrock <pie...@pirsoft.dnsalias.org>: > >> Hi Gerald, >> >> Gerald Murray schrieb: >>> Tested: >>> LiDE 35: 150,300,600,1200 using usb-1.1. > --snip-- >> That is probably a calibration problem. There is no easy way to fix >> that. What helped Henning was to clean the calibration area. The backend >> is currently not able to cope with (much) dirt there. You can get a >> distorted raw scan of the calibration area by enabling debugging. That >> should give you a file named "black_white_shading.pnm". When scanned at >> the higher resolutions(>=600dpi), it should have vertically striped >> area(s), but only very few dirt particles. > > I have not figured out how to clean the calibration area. There was no > instructions that came with the scanner. Is there some guide to how > to take the parts apart? There is one possible plastic hook pair on the > bottom, but it looks like a manuafacturer-only access point, requiring a > special tool.
Then i guess you need to live with the vertical stripes. But please send the black_white_shading.pnm from a 1200dpi scan so i can try to find a better calibration algorithm. >>> Also a few slices across the image, possibly from a >>> jerk of the head at that point in the scan. On the whole, an acceptable >>> image. >> Did this happen because the scanner moved the head back to restart at >> the buffer overflow position? If that is the case, i need to do some >> more tuning on the acceleration tables. That should definitely not >> happen(Though it is no reason not to put the code into sane-backends). > > It happened at 10 cm of an 11cm postcard scan. The scanner does quite > a bit of shuffling, and I thought it might be related to that forward/reverse > timing in the shuffle. > I guess that did not happen all the time at the same position? >>> HP2400: no change, not working. >> Not working as in "refuses to move head/deliver useful data" or as in >> "provides a 2400x1200dpi image"? For the latter case i do have a patch, >> enabling a nearest match interpolation. > > The head never moves. It goes into a calibration at the beginning, and > never completes the calibration correctly, and then times out with a > question on the lamp: > [genesys] genesys_warmup_lamp: warmup timed out after 46 seconds. Lamp > defective? > scanimage: sane_start: Error during device I/O > Sorry, misread "HP2400" to be "2400 dpi".. Regards, Pierre