Lab vs RGB vs HSV color spaces for color detection?

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I'm having trouble understanding why there exist multiple color spaces. That is, informatically, all three spaces have the same color information content, so why would one perform better or worse for selecting out, say, red?
I saw from the example demo by ImageAnalyst that lab space is very good for detecting a particular color selected by the user, but I just don't get why the performance should be different for any color space? does it have to do with some computational issues?
thank you for your time.

Accepted Answer

Image Analyst
Image Analyst on 5 Aug 2013
You have to look at the shape of the gamut in the different color spaces to understand which color space will be best. Unfortunately MATLAB does not have a gamut visualizer like imageJ does ( http://rsb.info.nih.gov/ij/plugins/color-inspector.html) so you'll have to use that to understand your gamut. I've been telling the Mathworks for years that it's my number one most requested upgrade they can do. For example imagine that you have a gamut that is like a cigar shape extending out into the orange region of LAB/HSV space. You're not going to be able to carve out those pixels with a box, which is what you get if you set thresholds in LAB color space, but if you set thresholds on H, you can carve out a sector going radially, for example you can get all hues going from 40 to 50 degrees, which is the orange region.
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Image Analyst
Image Analyst on 9 Apr 2014
Glad I could help. You can also vote for my answer if you want.

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