bitmap image
Synonyms: raster image
A digital image that is organized as a rectangular grid of pixels, like a tile mosaic.
A bitmap image can be reproduced at any size. However, there is a limited amount of detail available. If a bitmap is reproduced at too large a size, the individual pixels become visible as squares, giving the image a blocky or mosaic appearance. (The definition of "too large" depends on the DPI or PPI of the device being used to reproduce the bitmap image.)
As the amount of detail in a bitmap image increases, the size of the file increases exponentially.
In the EPUB e-book file format, bitmap images are normally included as either JPEG or PNG files.
Also see: vector image.