Re: Measuring 'Dominant Wavelength'?

Posted by Gabriel Landini on Jan 28, 2015; 9:37am
URL: http://imagej.273.s1.nabble.com/Measuring-Dominant-Wavelength-tp5011335p5011343.html

On Tuesday 27 Jan 2015 19:31:27 Greg <[hidden email]> wrote:
> Probably the best you can do without a spectrometer would be to convert
> the color space of your image to a cylindrical one such as HSV and use
> the H (Hue) value to get an approximation of the dominant color (not
> wavelength).   Alternatively, you might get better results with a simple
> diffraction grating spectrometer in front of the camera ala the public
> lab spectrometer.

Hm... not in HSV space derived from RGB images...
E.g. "Yellow pixels" could be proper "yellow light", or the "sum or red and
green light". You can't reach any conclusions with HSV.

If you want to do this properly, with images, you could use a calibrated
greyscale camera and a bank of narrow band pass filters or one of those fancy
"tunable filters" like the Varispec system.

Cheers

Gabriel

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