A NOVEL APPROACH TO COMPRESSING BI-LEVEL IMAGES
Original Publication Date: 1996-May-01
Included in the Prior Art Database: 2002-Apr-09
One area ofgrowing interest is the ability to send a printed document containing dithered (half-tone) images, such as in newspaper articles and reports, from a fax machine to a wireless device equipped with a monochrome or color LCD screen. A major goal ofportable wireless communications is to reduce the tile size for transmission and storage of such services. This paper describes a novel method for compressing bi-level images beyond that achievable by standard techniques, Continuous-tone grey-level images are commonly used in computers and included in newspapers, arti- cles, reports and documents. In computers equipped with LCD screens it is relatively common to be able to display up to 256 shades of grey color. However, most printed media do not render the image using colors that are shades ofgrey but instead use a tech- nique called half-toning. In half-toning a grey pixel is represented using a block ofpixels where the vis- ual perception of various shades of grey is achieved by different distributions of only black and white pixels (no grey) in the block.