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From: littauer@uts.amdahl.com (Tom Littauer)
Newsgroups: comp.graphics
Subject: Re: COLOR SCANNING.
Summary: Watch out for IR when using TV cameras
Message-ID: <80MS02cY76x401@amdahl.uts.amdahl.com>
Date: 20 Dec 89 16:29:10 GMT
References: <13428@s.ms.uky.edu> <2300002@hprnd.HP.COM>
Reply-To: littauer@amdahl.uts.amdahl.com (Tom Littauer)
Organization: Amdahl Corporation, Sunnyvale CA
Lines: 35

In article <2300002@hprnd.HP.COM> tms@hprnd.HP.COM (Thomas Skibo) writes:
>
>/ hprnd:comp.graphics / munish@ms.uky.edu (Munish Mehra) /  2:25 pm  Dec  5, 1989 /
>> There are many scanners that scan images into 16,32 or more gray levels .
>> (Some very reasonable)
>> Is it possible to use color filters / colored cellophane paper to
>> scan an image through Red, Green and Blue Filters and then combine
>> the RGB values to create a colored image ?
>
>I tried a similar approach with a B/W video camera and did not achieve very
>good results.  The problem was that the video camera was not equally sensitive
>to all visible colors.  The three filtered images were not true representations
>of the red, green, and blue components.

This is true, but you can scale the individual components.

Other problems I've run into using RS-170 cameras:

Many are sensitive to IR, and most RGB filters pass IR. Get an IR-blocking
filter for best results.

Be sure to include samples of pure black and pure white (as you define them)
in each frame you digitize for scaling purposes. Many cameras do some form
of AGC even if you turn off all the widgets marked AGC.

Good Luck,
Tom Littauer
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