[sane-devel] reverse engineering techniques

Henning Meier-Geinitz henning@meier-geinitz.de
Sun, 8 Aug 2004 11:38:03 +0200


please also reply to sane-devel, as other people may laso have
comments about your questions.

On Tue, Aug 03, 2004 at 10:51:46AM -0400, Dave Burns wrote:
> Henning - thanks for the reply. It was the only one I got. Your ideas are
> ones I hadn't considered (this is the first time I've delved into scanner
> internals) so I'll do some more experiments with this in mind.
> The notion of exposure times leads me to a new question though. Since the
> scanner head is moving past/over the image, I'm not clear on how exposure
> times would work. I'd think that the only way to change exposure times is to
> change the speed of the scanning head but, at least on the FS4000, there's
> already a separate parameter for controlling that. Do I not have a good
> mental model for what's going on inside? (If it matters, this is a film
> scanner - not sure if you know of any differences as to how they might
> handle exposure differently from flatbeds.)

I don't really know how it works. However, for CIS scanners you could
think about how longh the different LED lines are turned on. The
longer they are turned on, the longer the exposure time is. Maybe you
can also influence the time a pixel is sampled with CCD sensors? The
maximum is limited by the motor speed but maybe you can decrese the