>  > Normal scanner operation is to scan one page. What I'd like to do is
>>  figure out how to put a scanner into some sort of "continuous" mode,
>>  where it scans forever, streaming data out. Then I could advance the
>>  film in front of the array at a suitable rate. I wonder if some
>>  scanners have a diagnostics mode, where you can get them to scan
>>  continuously?
>>
>
>Image sensors I'm familiar with integrate the pixels for a period of time,
>then shift out the image. If in a continuous mode, they are shifting out
>the previous set while integrating the new set. If in snapshot mode, they
>integrate, then shift. If your film is moving continuously, the
>integration would blur "vertical pixels." If the integration time is short
>enough, this problem can be minimized.

Right, my thought is to move the film slowly enough to minimize the 
blurring.  I'd have an automated scanning machine, so I would not be 
terribly concerned about how long it took. Worst case a stepper drive 
could be used to move/stop, but I think a continuous motion could 
work, experimentation would tell!

I wonder if I should look around for a *very old* scanner, with the 
thought that it would tend to have lots of individual chips to 
control things, rather than one big FPGA, with the hope that I could 
get at the data I want, and perhaps trick the unit into continuously 
integrating.  Time to visit Goodwill I think.

>I understand this project is for scanning 35mm microfilm. Sounds like an
>interesting project! At some point, I'd like to take the old Federal
>Registers, available on microfilm, and scan them to a pdf. The software
>would have to figure out where one page ends and the next starts, since I
>don't think you can rely on sprocket holes like you can with motion
>picture film. Maybe you can?

I suspect you can't rely on the sprocket holes. I know I can't in my 
case, as the images were manually photographed and the spacing 
between pages is not fixed. Perhaps if the filming was automated, the 
page spacing is more precise, and you could?

For my use, I am OK with having one large data file that I would 
"manually" scroll through, I am thinking of writing software (if I 
ever get the hardware built!) that would in effect emulate a 
microfilm reader - I could go to an arbitrary point in the film, 
scroll, etc, and then "take a snapshot" to a JPG/PNG/etc picture file 
of the current page.
-- 

---
Chris Smolinski
Black Cat Systems
http://www.blackcatsystems.com
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