[Sidefx-houdini-list] COPS - Average Colour Luminance in Image

Mark Alexander malexander at sidefx.com
Fri Apr 20 16:23:09 EDT 2007


> and this has brought the result within a decent range.
>  
> (The result is 3.05 for a white image)
>  
> - I'm now multiplying by a 'magic' number 
> to get the results between 0 and 1


Ah, right. I forgot to mention you should run it through a Mono COP 
first to change RGB -> lum, and then just read the Red channel into 
CHOPs. It's 3x higher than normal because of the 3 RGB channels. Sorry, 
forgot about that :) At least that should reduce the 0.05 error to 
around ~0.01, which is probably acceptable.

M.



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