On 7/5/08, m. allan noah <kitno455 at gmail.com> wrote: > On 7/5/08, Simon Glass <sglass at bluewatersys.com> wrote: > > Hi, > > > > On a Fujitsu FI-5750C I get JPEG working fine on the flatbed, or when > > using ADF on the front / back size simplex. > > > > But when I scan duplex JPEG, I get an image which is only half as wide > > as it should be, and seems to have 8 lines of valid data, then 8 lines > > from somewhere else, etc. Also the JPEG apparently has about half its > > size in extraneous data (I get a warning when loaded into gimp). > > > fujitsu duplex scanners buffer the backside in their internal ram, and > you can request all of the frontside, then request all of the > backside. but, if the machine does not have enough ram to hold the > backside, it may error. so, i default to alternating front/back reads, > and buffer the backside in the backend. most machines can handle > either of those approaches. > > jpeg duplex seems to be a different story- the machines only alternate > or serialize, but not both, you have a machine that serializes, so the > attempt to descramble it does the opposite. > > there seems to be no way to detect the proper format by querying the > scanner, but i might be able to inspect the image data. let me look.
i invented a mechanism to determine the interlacing format while scanning, and switch modes on the fly. I have tested with a small, alternating scanner (fi-4120c2) and a large serialized scanner (fi-4990C). Simon has confirmed that this fixes the issue for his machines (one alternating, one serial) without hardcoding anything. i also fixed the sane_get_parameters bug Simon pointed out in another email. all users of the fujitsu backend should really update to v70, to get these (and quite a few other) fixes. allan -- "The truth is an offense, but not a sin"