In the Window where it shows Digital Color Meter, what is the unit of measurement used in RGB?

  • Protip: If you look in the menu bar, you can change the unit to something like hexadecimal. – haykam Dec 5 '16 at 15:28
  • RGB and Hexadecimal colors actually have the same number of available colors: 16,777,216 (256^3), though I've never heard of a specific unit of measurement. The only difference between RGB and Hex is syntax. – Charles John Thompson III Dec 5 '16 at 15:56

I don't think there's a particular unit of measurement, just 256 "steps" between lowest and highest for each of red, green and blue.

Take a look at the Wikipedia page for Adobe RGB - it has some useful diagrams. In particular, the diagram showing "The CIE 1931 xy chromaticity diagram showing the primaries of the Adobe RGB (1998) color space" - the three points of the triangle (the "primaries") correspond to these points (moving anti-clockwise, from the right):

  • R = 255, G = 0, B = 0
  • R = 0, G = 255, B = 0
  • R = 0, G = 0, B = 255

The same system of 256 steps is used for other colour spaces like sRGB, even though they may well be a different size to Adobe RGB's colour space.

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  • I am using this to test how strong the intensity of the glow output by a Bioluminescent Algae, is there another form of measuring that? – LilVinny Dec 5 '16 at 23:22
  • I honestly don't know! How exactly are you measuring the intensity? (Or, perhaps more importantly, how would intensity normally be measured?) The digital colour meter has an option for L * a * b (where 'L' is "lightness", from 0 to 100) - it's possible that that might be appropriate? (However, I suspect some calibration would be required). – John N Dec 6 '16 at 8:42

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