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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

Pixel Type Data 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

Function Purpose Replaces
RGBtoHLS Given 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
HLStoRGB Given an HLS pixel, returns an RGB pixel. PF_HLS_TO_RGB
RGBtoYIQ Given 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
YIQtoRGB Given a YIQ pixel, returns an RGB pixel. PF_YIQ_TO_RGB
Luminance Given an RGB pixel, returns 100 times its luminance value (0 to 25500). PF_LUMINANCE
Hue Given an RGB pixel, eturns its hue angle mapped from 0 to 255, where 0 is 0 degrees and 255 is 360 degrees. PF_HUE
Lightness Given an RGB pixel, returns its lightness value (0 to 255). PF_LIGHTNESS
Saturation Given an RGB pixel, returns its saturation value (0 to 255). PF_SATURATION