= Adjust colors, levels, black point, and white point =

Color correction nodes in compositing networks appear with a blue
background. Houdini collapses consecutive color correction nodes into
one operation, saving memory, improving performance and avoiding
clipping/quantization issues.


TIP:
    The Bright, Contrast, and Gamma operations can optionally affect
    individual channels.

table>>
    tr>>
        th>> To adjust...
        th>> Use this operator
    tr>>
        td>> Brightness
        td>>
            [Bright COP|Node:cop2/bright]
    tr>>
        td>> Contrast
        td>>
            [Contrast COP|Node:cop2/contrast]
    tr>>
        td>> Gamma
        td>>
            [Gamma COP|Node:cop2/gamma]
    tr>>
        td>> Brightness, Contrast, and Gamma for the overall image,
        highlights, midtones, and lowlights
        td>>
            [Color Correct COP|Node:cop2/colorcorrect]
    tr>>
        td>> Map one color range to another
        td>>
            [Color Map COP|Node:cop2/colormap]
    tr>>
        td>> Clamp minimum and/or maximum color values
        td>>
            [Limit COP|Node:cop2/limit]
    tr>>
        td>> Hue, saturation, and/or value
        td>>
            [HSV COP|Node:cop2/hsv]
    tr>>
        td>> Color curves
        td>>
            [Color Curve COP|Node:cop2/colorcurve] or [Hue Curve
            COP|Node:cop2/huecurve]
== Black point and white point == (comp_blackwhite)

    For planes with integer data, by default 0 means black and the
    maximum value (which depends on whether you are using 8, 16, or
    32-bit integers) is white. However, you can adjust which level
    corresponds to black and which level corresponds to white. This
    allows you to reduce the head and foot clipping errors at the
    expense of quantization errors.

    NOTE:
        For planes with floating point data, 0 is _always_ black and the
        maximum value is _always_ white. You cannot set black and white
        points for floating point data.

    For example, a 16 bit image with black and white points set at
    24,000 and 40,000 gives you 16,000 levels between black and white,
    and quite a bit of head and foot room (the full range is -1.5 to
    2.6).

    Houdini always displays color values as a range from 0 to 1. So, if
    you adjust the black/white points, you can have values less than 0
    or greater than 1, which reduces clipping of values during
    calculations.

    For example, for an 8-bit integer channel, you could set the black
    point to 64 and the white point to 192. In Houdini, the 0 color
    value now corresponds to a value of 64 in the channel, and the 1
    color value now corresponds to a value of 192 in the channel. So,
    the range of color values you can use in Houdini is now from
    (0-64)/(192-64) = -0.5 to (255-64)/(192-64) = 1.492.

    To set the black point and white point of an image, use the [Levels
    operator|Node:cop2/levels].