[PD] pdp color seperation

[Mathieu Bouchard]

On Thu, 7 Dec 2006, metafor wrote:

> i am wondering if someone already did a patch to separate color channels 
> in order to track some specific objects more easily. for example only 
> display objects with have a certain red value (bigger 200 in RGB) and so 
> on.

Don't do that, because then it can't distinguish between red, yellow, 
white and purple. There are a bunch of techniques for dealing with that. 
For example, use Red minus Green minus Blue, as a way to detect only Red 
but not other colours. (I did that for my currently-running exhibition 
with Andrée Préfontaine at Glendon Gallery, that has a fruit-controlled 
audio sampler)

I don't know how to do that in GEM, but in GridFlow, you just multiply 
each picture by a column matrix; e.g. here are objects for separating 
redness and greenness:

[#inner (3 1 # 1 -1 -1)] for the tomato slice
[#inner (3 1 # -1 1 -1)] for the kiwi slice

  _ _ __ ___ _____ ________ _____________ _____________________ ...
| Mathieu Bouchard - tél:+1.514.383.3801 - http://artengine.ca/matju
| Freelance Digital Arts Engineer, Montréal QC Canada