Compression/expansion circuit having transfer means and storage means

Abstract

A compressing/expanding circuit for compressing and expanding image data by a JBIG method comprises a memory medium such as floppy disk or hard disc to store the image data, a compressing circuit to compress the data, an expanding circuit to expand the data, a transfer circuit to transfer the data stored in the memory medium to the compressing circuit or expanding circuit, a storage controller to store the data compressed by the compressing circuit or the data expanded by the expanding circuit to the memory medium, a compression controller to control the transfer circuits compressing circuit, and storage controller so as to repetitively operate, an expansion controller to control the transfer circuit, expanding circuit, and storage controller so as to repetitively operate, and a designating circuit to designate either one of the compressing process and the expanding process. In the case where the compressing process is designated by the designating circuit, the transfer circuit, compressing circuit, and storage controller are controlled by the compression controller. In the case where the expanding process is designated by the designating circuit, the transfer circuit, expanding circuit, and storage controller are controlled by the expansion controller.