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
      >