Interactive contrast stretching

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  • tzellman

    Interactive contrast stretching

    Before I ask for help, let me give you my situation, including what I
    HAVE been able to do.

    I am trying to show an image (large, say the whole screen), and allow
    for instantaneous visual results with regards to a lookup table
    change. In essence, I am going for an interactive contrast stretch. I
    have been able to do this, but only for one band of a 3 band image.
    Thus, I have been able to create a byte array of pixels, and by
    changing the IndexColorModel for the image, I can update the screen to
    display "different" values instantaneously . Like I said, I have only
    been able to do this for 8 bit data.

    Knowing I can only do this for 8 bit arrays, I created 3 byte arrays
    of pixels. Each created image would then have its own IndexColorModel .
    However, I have been unsuccessful at taking these 3 created images,
    and on-the-fly (with little or no processing) creating one image that
    just references its red values from one image, its green values from
    theh second image, and its blue values from the third image. I have
    resorted to trying to use alpha values and drawing the 3 images one on
    top of another. This is not ideal, and does not produce the intended
    results.

    What I want to do is take a 3 band image (representing RGB) or
    essentially an int array, and have an IndexColorModel for each band,
    but have the actual image setup to feel like it is based off of 3 byte
    arrays. Thus, it looks up the red values in one model, the green in
    another, and the blue in another... and also looks up the
    corresponding pixels from its 3 RGB components. So, 3 look up tables
    consisting of 256 entries each... and only one image...

    I feel like I have searched high and far, but have come up with
    nothing that helps me with my intentions. The DirectColorMode l only
    allows me to set color masks... but doesnt give me the luxury of
    defining what pixels map to.

    Anyway, any help would be greatly appreciated.
    Thanks.
    -Tom
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