Re: Music Scanning, etc.
By Pete Woodworth
Hello, group!
> Mark A Fontana <mfontana@magnus.acs.ohio-state.edu> wrote:
> [snip]
> The IR exciter source for the phototransistors is a 150 W flood lamp
> powered by a clean DC supply (with variable intensity to compensate
> for various opacities of paper in the rolls).
>
> [clip]
> The system is pretty much done and works, but it has several big disadvantages.
> First of all, it can only scan plain 88-note rolls unless I perform some major
> modifications. Also, it can only scan rolls made before the 70's (or whenever
> companies like QRS started using translucent paper); this material just
> doesn't provide enough contrast for my optical scanner.
Mark, have you tried any of the following to increase contrast?
1. Use a Polarizing(r) filter on the light source? Filter media can be purchased from larger camera stores or from Edmund Scientific.
2. Illuminate the *paper*, possibly from the rear on each side of the tracker, and aim the phototransisters into a 'black hole'. Of course, this would invert the logic...
3. Use an infrared light source. Many (most?) photoelectric devices are extremely sensitive to IR. The paper may filter out more IR than it does visible light. (...or am I thinking of UV?) :)
-or any combination of the above. Just wonderin'.
Cheers! -Pete Woodworth
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(Message sent Wed 7 Jun 1995, 15:58:16 GMT, from time zone GMT-0700.) |
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