A bitmap image represents a visual scene or image as a matrix of pixesl each of which is a binary representation of a colour. This may be direct, for example encoding red, blue and green levels each as 8 bit values, or may be indexed, wheer each pixel is an index into a colour map. The latter is less common in modern formats. Often bitmap images are compressed so that the storage format does not driectly represent the pixels, but these can be restored for display or processing.
Used on Chap. 12: page 273