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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