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### From the subjective to the objective

Posted: Sat Nov 17, 2012 4:08 pm UTC
I'm interested to your approach there XKCDans.

Suppose you want to map a RGB colour to a "colourful" measure (as in, "intense colour", not "variety of intense colours"). How would you proceed?
To get thing started, I could envision 2 approaches:

1) An heuristic: considering 'vivid' is NOT 'white', 'gray', or 'black', maybe something like max ( (R-G)^2 , (R-B)^2, (R-G)^2 ). This could be modified to account for high Rs having a better return or something.

2) Get people online to vote on how vivid a colour is ("<blink>Can you answer the same than the majority? Win an iPhone!</blink>"). Then use those answers to interpolate a function f(U,V) so that we get
vividness = luminance * f(chrominance)

What would you do?

### Re: From the subjective to the objective

Posted: Sat Nov 17, 2012 5:52 pm UTC
Menacing Spike wrote:1) An heuristic: considering 'vivid' is NOT 'white', 'gray', or 'black', maybe something like max ( (R-G)^2 , (R-B)^2, (R-G)^2 ). This could be modified to account for high Rs having a better return or something.

I would do something along these lines although I feel like this exact algorithm would bias against non-primary colours. What would probably be better is to convert into a hue-sat-lum colour space and then have "vividness" being some function of primarily saturation and luminosity (possibly with some slight weighting to make reds more vivid than blues).

### Re: From the subjective to the objective

Posted: Sat Nov 17, 2012 8:20 pm UTC
It seems to me that in hue-saturation-value coordinates, 'colourful colours' would be those with with high saturation and high value. In other words, you'd just want a function of saturation and value that was monotonically increasing in both. It is an interesting question, though, whether hue plays a role in how we perceive the vividness of a colour. I can put myself in a frame of mind where I say, 'no, a vivid blue and a vivid red are equally colourful, just different colours' or one where I say, 'yes, reds and yellows are more vivid than blues and greens'.