detect colors

[imayub]

i have to build a circuit and that will detect the 8 basics colors. Any help would be appreciated.

thanks,

 

[IRstuff]

A little more information would be appreciated:

Are you trying to build a spectrum analyzer?

why 8? ROYGBIV gives 7

how much money do you have to spend? TTFN

 

[imayub]

i want to be able to detect red, yellow, blue, black, green, white, orange, purple, and maybe more such as brown, pink, etc.

i want to make it cheap, less than 10 dollars

i want to use in a manufacturing arm to detect different color pieces.

 

[IRstuff]

Suggestion:

study up on color theory. "pink" and "brown" are not a colors of monochromatic light, but are combinations of different wavelengths. study up on the CIE color map and tristimulus theory. Find a copy of ISO-10526, "CIE standard illuminants for colorimetry"

if you think you can do it for 10 dollars, good luck. In order to accurately measure color, you'll need to have 3 accurately calibrated tristimulus detectors or a decently calibrated spectrophotometer, in addition to at least one calibrated illuminant, none of which are even individually available at the price you state.

You might be able to get by with a color CCD and reference targets and use some image processing to compare sample to reference. Even this will cost you at least $30 for even the cheesiest web cam and you'll still need to get a stable and relevant light source. TTFN

 

[jbartos]

Suggestion: Supposing that one uses photo sensors calibrated to different colors.

 

[IRstuff]

Still requires optical filtering on the detector, neither of which could be done for $10 each, much less $10 for the minimum of 3 required to determine the tristimulus value. TTFN

 

[jbartos]

Suggestion: Visit

http://www.e-insite.net/ednmag/archives/1998/060498/12di.pdf

etc. for more info

 

[cbarn24050]

Hi, first you need to be sure what you mean by colour. Do you mean the wavelenths of light from an object, or do you mean the interpretation the eye/brain puts on them.