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12.12 Image.GD

DESCRIPTION
Handle encoding and decoding of GD images.

GD is the internal format of libgd by Thomas Boutell, http://www.boutell.com/gd/ It is a rather simple, uncompressed, palette format.

METHOD
Image.GD._decode,
Image.GD.decode,
Image.GD.decode_alpha,
Image.GD.decode_header

SYNTAX
object decode(string data)
object decode_alpha(string data)
mapping decode_header(string data)
mapping _decode(string data)

DESCRIPTION
decodes a GD image

The decode_header and _decode has these elements: 

"image":object            - image object    \
"alpha":object            - decoded alpha   |- not decode_header
"colortable":object       - decoded palette /


"type":"image/x-gd"       - image type
"xsize":int               - horisontal size in pixels
"ysize":int               - vertical size in pixels
"alpha_index":int         - index to transparancy in palette
-1 means no transparency
"colors":int              - numbers of colors

METHOD
Image.GD.encode

SYNTAX
string encode(object image)
string encode(object image, mapping options)

DESCRIPTION
encode a GD image

options is a mapping with optional values: 

"colortable":object       - palette to use (max 256 colors)
"alpha":object            - alpha channel (truncated to 1 bit)
"alpha_index":int         - index to transparancy in palette

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