[sane-devel] Fujitsu JPEG Duplex Scanning

m. allan noah kitno455 at gmail.com
Sat Jul 5 12:27:44 UTC 2008

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.

"The truth is an offense, but not a sin"

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