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From: Chuck Simmons
Organization: You jest.
X-Mailer: Mozilla 4.61 [en] (X11; U; Linux 2.0.33 i586)
Subject: Re: Detecting colored objects
Date: Wed, 30 Oct 2002 01:01:20 GMT
NNTP-Posting-Date: Tue, 29 Oct 2002 17:01:20 PST
Harry Dellamano wrote:
> I would like to candle eggs that have 11 possible solid colors rolling down
> an assembly line. Once the color is determined a microprocessor will drop
> them into the correct bin. I do not know the best way to detect color on the
> fly. It would be nice if a photocell would put out different current levels
> that can be calibrated and detected by a threshold detector. Once I get by
> the light to electronic transducer I am home free. What is the best photo
> detector and light source for this job??
What about a white light source, three filters (red, green and blue) and
three sensitive photodetectors? Normalization for variation in
absorbtion and brightness of the light can be done using the sum of the
three detectors. Do a search on colorimetry. This will give you clues
about calibrating initially to a reference gray or white and then
recognizing color with pretty good resolution.
Note that suitable colorimetry filters can be purchased from several
different optics companies. Edmund Industrial Optics has both additive
and subtractive filters designed for machine vision applications.
... The times have been,
That, when the brains were out,
the man would die. ... Macbeth
Chuck Simmons email@example.com
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