mapping luminosity -> colour gradient

Discussion in 'Photoshop Tutorials' started by Peter Williams, Oct 29, 2004.

  1. Hello.

    I have a black and white image. Id like to smoothly map the luminosity
    values to rgb values in the image.

    An example would be a black and white image of a cloudy sky. Id like
    to colorize the image so that eg. the brightest clouds stay white, the
    darkest clouds become a reddish blue, the midrange luminosity values
    become a bright yellow etc. I suppose in general Im looking for a way
    to map luminosity values to colours in a gradient, where Ideally I can
    define/create the gradient as I please. Even better would be where I
    can alter the mapping on the fly so that I change the mapping/gradient
    in retrospect at any time without altering the original/underlying
    image pixels (ie the luminosity information).

    Id be very grateful for any good suggestions on how to best achieve
    such an effect.
    Thanks in Advance.
     
    Peter Williams, Oct 29, 2004
    #1
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  2. Peter Williams

    Mike Russell Guest

    Check out gradient map - I think it will do exactly what you want: smloothly
    map a grayscale value to a color.
     
    Mike Russell, Oct 29, 2004
    #2
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  3. Peter Williams

    Aerticus Guest

    Maybe even grayscale -> duotones (this allows duo tri and quad tone effects)
    b

    then swap image mode back to rgb?

    Aerticus
     
    Aerticus, Oct 29, 2004
    #3
  4. Peter Williams

    Tom Nelson Guest

    You can also do this with Curves. Change the mode to RGB, then invoke
    Curves and move the endpoints around for each color channel. You can
    cmd (ctrl) click a point on the curve to set an intermediate point you
    can manipulate.
    Tom Nelson
    Tom Nelson Photography
     
    Tom Nelson, Oct 29, 2004
    #4
  5. Thanks for the helpful suggestions.
     
    Peter Williams, Nov 1, 2004
    #5
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