Image data compressing method and apparatus which compress image data separately by modifying color

摘要

An image data compressing apparatus comprises a color selecting unit, a data separating unit and a data compressing unit. The selecting unit selects an arbitrary color contained in an original map image. The separating unit separates the original image data into a modified color data and a selected position data. The compressing unit compresses these data separately from each other to improve data compression efficiency. The modified color data may be data in which a color of a background portion is made equal to a color of a road, and the background color may be a color which is most popularly used.