1. Most commonly, bitmaps refers to raster graphics. Suppose the smiley face in the top left corner is an RGB bitmap image. ...
2. Also, bitmaps refers to arrays of boolean values, when stored efficiently so that 8 array elements are stored to the byte. They are frequently used to indicate whether an allocation unit is free or used in memory management, file systems and databases. In computer programming, an array, also known as a vector or list, is one of the simplest data structures. ... Memory management is the act of managing computer memory. ... In computing, a file system is a method for storing and organizing computer files and the data they contain to make it easy to find and access them. ... A database is an organized collection of data. ...
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Then for each square, we initialize the rank_attacks[square][rank_contents] to the bitmap that matches the squares that a rook/queen on "square" could move to, assuming the rank is occupied as per the eight bit value "rank_contents".
For example, take the occupied_squares bitmap used earlier, but add a rook on square F5 instead of a bishop as in the previous example (figure 8), and assume we are trying to initialize rank_attacks[37][100] (37 is the square F5, and 100 represents the occupied squares on that rank, 01100100).
Perhaps the primary performance improvement to using bitmaps came from the Crafty project however, when the concept of "rotated bitmaps" was developed as an alternative to the classic incremental update approach used in chess 4.0, because this produced a substantial performance increase with no loss at all in capability.
Bitmaps are defined as a regular rectangular mesh of cells called pixels, each pixel containing a colour value.
As with 8 bit grey bitmaps each pixel has one byte associated with it only now the value in that byte is no longer a colour value but an index into a table of colours, called a palette or colour table.
A common operation that reduces the size of large 24 bit bitmaps is to convert them to indexed colour with an optimised palette, that is, a palette which best represents the colours available in the bitmap.
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