Method and system for context-based adaptive binary arithmetic coding

Abstract

A method of image coding wherein an image is divided into blocks having a plurality of pixels. A transform coding operation is performed on a block of pixels to produce a corresponding block of transform coefficient values, which is scanned to produce a scanned array of coefficient values represented by a plurality of number pairs having a first and a second number. The first and second numbers are assigned to one of a plurality of contexts (14) representative of the number pairs. The first number of a number pair is assigned to a context based on a first number of another number pair. Alternatively, the second number of a number pair is assigned to a context based on the first number of the number pair (16). Furthermore, a number indicative of the number of non-zero coefficient values in the block of transform coefficient values is determined and assigned to a context.

Description

[0001] This application is a divisional application of the patent application with application number 02822672.0. Technical field

[0002] The present invention generally relates to still image and video sequence compression, and more particularly to a context-based adaptive binary arithmetic coding method and system. Background technique

[0003] A digital image in uncompressed form contains an array of image pixels or primitives. For example, in a common digital image format known as the Quarter Common Intermediate Format (QCIF), the image or frame contains 25,344 pixels arranged in an array of 176×144 pixels. Each pixel is represented by a certain number of bits in turn, and they convey information about the brightness (brightness) and / or color (chromaticity) of the pixel. In addition, there are different schemes for representing brightness and / or chroma in digital images. The so-called YUV color model is usually used. The brightness or Y component represents the pixel brightne...

Images