Patent ID: 6427025
Filing Date: 2002-07-30
Classification: G06T,H04N

Abstract:
An image data compression apparatus comprising:an input unit adapted to input multilevel image data of an image; a judgment unit adapted to judge a type of an image area of the inputted multilevel image data; a non-reversible compression unit adapted to non-reversibly compress the inputted multilevel image data; and a reversible compression unit adapted to reversibly compress the inputted multilevel image data, wherein said apparatus compresses areas comprising the image according to a result obtained by said judgment unit, such that: when said judgment unit judges an area to be a first type of image area, final compressed data is generated and outputted by non-reversibly compressing data of the first type of image area, and when said judgment unit judges an area to be a second type of image area, reversibly compressed data is generated by reversibly compressing data of the second type of image area using said reversible compression unit, the reversibly compressed data being output as final compressed data when an amount of the reversibly compressed data is not more than a predetermined value, and non-reversibly compressed data is generated by non-reversibly compressing data of the second type of image area using said non-reversible compression unit, the non-reversibly compressed data being output as final compressed data when an amount of the reversibly compressed data is more than the predetermined value, and wherein said apparatus compresses a third type of image area comprised of a natural image and another image according to a result obtained by said judgment unit, generates reversibly compressed data by reversibly compressing data of the third type of image area where a part of the natural image is replaced with the other image in the third type of image area, and, when an amount of the reversibly compressed data is not more than the predetermined value, outputs as final compressed data the reversibly compressed data and compressed data obtained by non-reversibly compressing the part of the natural image of the third type of image area and an interpolation value, and, when the amount of the reversibly compressed data is more than the predetermined value, outputs as final compressed data compressed data obtained by non-reversibly compressing the data of the third type of image area.