Hi all, A while back I got an Epson Perfection 4490 Photo and found out that the 16-bit scanning didn't work, so I made a patch for the epkowa driver to fix the problem. I posted it on the avasys message board, but evidently didn't do enough research to find out that I could've posted it here. Now Johannes Meixner has alerted me to the fact that Olaf Meeuwissen is active on this list and the epkowa driver is indeed on-topic.
My patch has been mentioned on this list before: http://lists.alioth.debian.org/pipermail/sane-devel/2007-September/019874.html but now I've split it into the actual 16-bit fix and some entirely optional code cosmetics. The reason that 16-bit scanning didn't work is that the 4490 is a 'D' level scanner, which means that it doesn't do colour correction. Instead, the driver does this (which means that 16-bit raw data from the scanner is all the more important to reduce discretization) but the driver assumes that the data is 8-bit RGB. So the first patch merely adds a 16-bit version of color_correct and a check for the depth. The modified code path is only reachable for D-level scanners and should change nothing for the 8-bit case. The second and third patch are just minor cleanup that should have no noticable effects except on code size. The first-middle-last cases of the data download are rolled into a smaller (and IMHO more readable) loop, and a redundant memset is removed. Cheers, //Carl -- Carl Troein - carl.troein at ed.ac.uk http://carl.troein.com/ -------------- next part -------------- A non-text attachment was scrubbed... Name: level_D_16_bit.patch Type: text/x-patch Size: 3435 bytes Desc: not available Url : http://lists.alioth.debian.org/pipermail/sane-devel/attachments/20080524/3aededc8/attachment.bin -------------- next part -------------- A non-text attachment was scrubbed... Name: main_loop_deunroll.patch Type: text/x-patch Size: 4847 bytes Desc: not available Url : http://lists.alioth.debian.org/pipermail/sane-devel/attachments/20080524/3aededc8/attachment-0001.bin -------------- next part -------------- A non-text attachment was scrubbed... Name: minor_cleanup.patch Type: text/x-patch Size: 555 bytes Desc: not available Url : http://lists.alioth.debian.org/pipermail/sane-devel/attachments/20080524/3aededc8/attachment-0002.bin
