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color-space-conversion

Color Space Conversion

Section titled “Color Space Conversion”

Different pixel formats are useful for different operations. After Effects exposes its internal functions through PF_ColorCallbacksSuite. Here are the supported formats.

Pixel Types For Different Color Spaces

Section titled “Pixel Types For Different Color Spaces”
Pixel TypeData Structure
8 bpc ARGB
typedef struct {
  A_u_char alpha, red, green, blue;
} PF_Pixel8;
16 bpc ARGB
typedef struct {
  A_u_short alpha, red, green, blue;
} PF_Pixel16;
32 bpc ARGB
typedef struct {
  PF_FpShort alpha, red, green, blue;
} PF_PixelFloat, PF_Pixel32;
HLS (Hue, Lightness, Saturation)
typedef PF_Fixed PF_HLS_PIXEL[3]
YIQ (luminance, in-phase chrominance, quadrature chrominance)
typedef PF_Fixed PF_YIQ_PIXEL[3]

Plug-ins can draw on image processing algorithms written for nearly any color space by using the following callback functions.

Color Space Conversion Callbacks

Section titled “Color Space Conversion Callbacks”
FunctionPurposeReplaces
RGBtoHLSGiven an RGB pixel, returns an HLS (hue, lightness, saturation) pixel. HLS values are scaled from 0 to 1 in fixed point.PF_RGB_TO_HLS
HLStoRGBGiven an HLS pixel, returns an RGB pixel.PF_HLS_TO_RGB
RGBtoYIQGiven an RGB pixel, returns a YIQ (luminance, inphase chrominance, quadrature chrominance) pixel. Y is 0 to 1 in fixed point, I is -0.5959 to 0.5959 in fixed point, and Q is -0.5227 to 0.5227 in fixed point.PF_RGB_TO_YIQ
YIQtoRGBGiven a YIQ pixel, returns an RGB pixel.PF_YIQ_TO_RGB
LuminanceGiven an RGB pixel, returns 100 times its luminance value (0 to 25500).PF_LUMINANCE
HueGiven an RGB pixel, eturns its hue angle mapped from 0 to 255, where 0 is 0 degrees and 255 is 360 degrees.PF_HUE
LightnessGiven an RGB pixel, returns its lightness value (0 to 255).PF_LIGHTNESS
SaturationGiven an RGB pixel, returns its saturation value (0 to 255).PF_SATURATION