1. An image processor comprising: a background remover which removes background from image data; a divider which divides the image data, which have been subjected to background removal by said background remover, to a plurality of blocks; an attribute discriminator means for discriminating an attribute of image data in each of the blocks obtained by said divider; and a compressor which compresses the image data in each block, from which the background has been removed, according to the attribute of the block discriminated by said attribute discriminator means.