Hello, Am Montag, den 05. Mai schrieb Stef: > On 25/04/2014 02:55, Andrew Kanaber wrote: > >I hit the same problem with a Canon LiDE 110. I tried measuring the > >distortion by scanning a sheet of graph paper in various modes. > > > >With sane 1.0.24 in 600dpi lineart and gray modes the scan is > >stretched vertically by about 30%. Color mode scans are actually > >also stretched at 600dpi, but much less noticeably by about 2%. The > >stretching is still visible though if you compare the scanned > >images side-by-side. With version 1.0.22 the lineart and gray scans > >are correct at 600dpi but the 2%-ish stretching is still present in > >600dpi color mode. > > > >In case it helps I've put some of the scans up at > >http://www.chiark.greenend.org.uk/~akanaber/lide110/ > > > >Let me know if there's something else I can do that might help, > > > >Andrew > > > >M G Berberich wrote: > >>Hello, > >> > >>Canon LiDE 210 with sane-backends 1.0.24 (libsane:amd64 1.0.24-1.1+b1 > >>from debian testing) has problems with 600 dpi gray and lineart. > >> > >>In 600 dpi gray and lineart the scan is partial and aspect-ratio is > >>not correct. Vertically only about ? of the area is scanned and then > >>scaled to the area, horizontally all is fine. (So probably the driver > >>sets the wrong scanline-skip (to small)). > >> > >>This worked in older versions, at least 1.0.22. > >> > >>600 dpi Color-scanning works fine, so do preview, 300dpi and 1200 dpi > >>in all modes. > >> > >>2400 dpi and 4800 dpi do not work at all, but never did. > >> > >> MfG > >> bmg > > Hello, > > the vertical resolution is given by the motor speed which is eventually > an int. So rounding errors may give ~2% distortion: > target=((exposure * dpi) / base_dpi)>>step_type; > Maybe by decreasing or increasing slightly exposure time rounding errors > could be mitigated, but changing exposure may raise other problems. If the > windows driver can do it, I'll manage to find something. > > I'll check how the gray scan beahves. The change between 1.022 and > 1.0.24 is to use the LINESEL function when we try to scan below the minimal > scanning speed of the motor. This should affect scans below 600 dpi, but not > 600 dpi which is the minimal scanning speed. > > 2400 and 4800 dpi scans works on my LiDE 210. So I'd need some logs or > better information on what is not working for you.
Made some logs and images. Please see http://www.m-berberich.de/sane/ Details are in Readme.txt > I'm currently working on shading calibration problems for gl646 based > scanners (HP2400 and HP3670). I'll look into this issues when I have > finished it. If you have time for it, you can open a bug in the bug tracker > (https://alioth.debian.org/tracker/?group_id=30186) and assigned it to me. > > Regards, > Stef MfG bmg -- ?Des is v?llig wurscht, was heut beschlos- | M G Berberich sen wird: I bin sowieso dagegn!? | berberic at fmi.uni-passau.de (SPD-Stadtrat Kurt Schindler; Regensburg) | www.fmi.uni-passau.de/~berberic
