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Let's take the example of the letter J from the bitmap article
....X. ....X. ....X. ....X. ....X. ....X. X...X. .XXX.. ...... ......It is represented in an similar, but even simpler file format version PBM (monochrome) as follows
P1 # This is an example bit map file j.pbm 6 10 0 0 0 0 1 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 0 0 1 0 1 0 0 0 1 0 0 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0The P1 is the identificaton of the file format. The hash sign marks a commentary. And the next two numbers give the width and the height. Then follows the matrix with the pixel values (in the monochrome case here only zeros and ones).
This file can be converted by two conversion programs from the netpbm package for example to a bmp file:
pgmtoppm "#FFFFFF" j.pbm > j.ppm ppmtobmp j.ppm > j.bmpDepending on the identification of the file format three similar file formats are distinguished, each with two versions:
In each case, the lower-numbered version refers to a human-readable, ASCII-based format similar to the one in the example above and the higher-numbered version refers to a binary format which is not human-readable but saves some space in the file, as well as being easier to parse due to the lack of whitespace.