# HP PhotoSmart strip lengths

john allen pitney (pitney@students.uiuc.edu)
Sun, 16 May 1999 21:45:54 -0500

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Hi all!

I'm playing with writing a little SANE frontend for my HP PhotoSmart. It's
not going to be as general as xscanimage or XSane; I only want to duplicate
the HP frontend (with improvements possibly) using GTK and SANE.

I wonder if anyone doing HP backend development has any leads on getting
the actual length of a film strip scan from the scanner? The method I've
found for acquiring a preview scan of a strip of unknown length, is to
scan the whole thing using the maximum length, buffer everything including
the spurious bytes at the end, then quit sane and do sane_init again. Now,
the HP backend reports a maximum scan length which corresponds to the
actual length of the film strip. Unfortunately, this method has a couple
of problems: I have to buffer a lot of junk then throw it away later, and
the sane quit/restart cycle is a little slow.

Is there any way to get the "end of film strip" signal from the scanner
during the sane_read() loop?

Also, I'm noticing that the image gets stretched in the Y direction for
any exposure setting which does not have a 100% Red exposure, that is,
only "Off" and "Negative" seem to have the proper dimensions. I might
be remembering the effect I saw incorrectly, but I noticed something
along these lines.

I'm using a Photosmart R032, by the way.

Thanks!

John Pitney

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