MacPaint file format

MacPaint        *.MAC
 
1 long          version number [0=ignore header, 2=header valid]
38 * 8 bytes    8x8 brush/fill patterns.  Each byte is a pattern row,
                and the bytes map the pattern rows top to bottom.  The
                patterns are stored in the order they appear at the bottom
                of the MacPaint screen top to bottom, left to right.
204 bytes       unused
-------------
512 bytes       total for header

< 51200 bytes   compressed bitmap data
-------------
< 51712 bytes   total
 
NOTE:  The version number is actually a flag to MacPaint to indicate if
the brush/fill patterns are present in the file.  If the version is 0,
the default patterns are used.  Therefore you can simply save a MacPaint
file by writing a blank header (512 $00 bytes), followed by the packed
image data.

Bitmap compression:
 
   The bitmap data is for a 576 pixel by 720 pixel monochrome image.
The packing method is PackBits (see below).  There are 72 bytes per
scan line.  Each bit represents one pixel; 0 = white, 1 = black.

See also PackBits Compression Algorithm

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