Forums > Jitter

Manipulating certain RGB values in a matrix

March 9, 2007 | 4:04 am

Hello, I’m sure this is probably very simple but I was hoping to pick someone’s brain about it.

Say I have a picture / video of some mountains and a sky and I’d like to manipulate only those RGB values that are close to the general sky-blue color. Ideally (and I’m sure this is easy in Max) a settable range of color tolerance as well as where in the matrix pixels are or aren’t affected. I know jit.chromakey will get the selection, but how might I manage the selected pixels? Perhaps that resulting matrix would be manipulated, then mixed back into the original? Guess I’m not sure how to manipulate, then re-mix back in so that the effect can be anything from subtle to extreme (generally most effects seem to be extreme).

Thanks for humoring me, it’s probably rather noobish of a question, but I’d be interested to see what others have done with this.

-CJ


March 12, 2007 | 10:45 pm

what about using those selected pixels from jit.chromakey as an alpha
channel, and going on from there?

On Mar 8, 2007, at 11:04 PM, Seejay James wrote:

>
> Hello, I’m sure this is probably very simple but I was hoping to
> pick someone’s brain about it.
>
> Say I have a picture / video of some mountains and a sky and I’d
> like to manipulate only those RGB values that are close to the
> general sky-blue color. Ideally (and I’m sure this is easy in Max)
> a settable range of color tolerance as well as where in the matrix
> pixels are or aren’t affected. I know jit.chromakey will get the
> selection, but how might I manage the selected pixels? Perhaps that
> resulting matrix would be manipulated, then mixed back into the
> original? Guess I’m not sure how to manipulate, then re-mix back in
> so that the effect can be anything from subtle to extreme
> (generally most effects seem to be extreme).
>
> Thanks for humoring me, it’s probably rather noobish of a question,
> but I’d be interested to see what others have done with this.
>
> -CJ
>


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