CMAP (0x434D4150)       /* Color map (Same as ILBM CMAP) */

This chunk is identical to the ILBM CMAP chunk as described in the IFF
ILBM documentation.

    struct CMAPstruct {
        ULONG       ID;
        ULONG       Size;
        UBYTE       ColorMap[Size];
    };

ColorMap is an array of 24-bit RGB color values.  The 24-bit value is
spread across three bytes, the first of which contains the red intensity,
the next contains the green intensity, and the third contains the blue
intensity.  Because DR2D stores its colors with 24-bit accuracy, DR2D
readers must not make the mistake that some ILBM readers do in assuming
the CMAP chunk colors correspond directly to Amiga color registers.