The class supports color-mapped images where the image data contains an index into a color table or images where the image data specifies the color directly.
For color-mapped images the color table contains up to 256, 24-bit colors. The image contains one byte for each pixel which is an index into the table to specify the color for that pixel. The color table and the image data are compressed as a single block, with the color table placed before the image.
For images where the color is specified directly, the image data contains either 16 or 24 bit color values. For 16-bit color values the most significant bit is zero followed by three, 5-bit fields for the red, green and blue channels.
Four bytes are used to represent 24-bit colors. The first byte is always set to zero and the following bytes contain the color values for the red, green and blue color channels.
The number of bytes in each row of an image must be aligned to a 32-bit word boundary. For example if an image if an icon is 25 pixels wide, then for an 8-bit color mapped image an additional three bytes (0x00) must be used to pad each row; for a 16-bit direct mapped color image an additional two bytes must be used as padding.
The image data is stored in zlib compressed form within the object. For color-mapped images the compressed data contains the color table followed by the image data. The color table is omitted for direct-mapped images.
This tag was introduced in Flash 2.