Manipulating certain RGB values in a matrix


    Mar 09 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

    • Mar 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 >