Adaptive coefficient scan order

Abstract

A digital media codec adaptively re-arranges a coefficient scan order of transform coefficients in accordance with the local statistics of the digital media, so that the coefficients can be encoded more efficiently using entropy encoding. The adaptive scan ordering is applied causally at encoding and decoding to avoid explicitly signaling the scan order to the decoder in the compressed digital media stream. For computational efficiency, the adaptive scan order re-arranges the scan order by applying a conditional exchange operation on adjacently ordered coefficient locations via a single traversal of the scan order per update of the statistical analysis.

Description

technical field [0001] The present invention generally relates to block transform based digital media (eg, video and image) compression. Background technique [0002] An Overview of Block Transform-Based Coding [0003] Transcoding is a compression technique used in many audio, image, and video compression systems. Typically uncompressed digital images and video are depicted or captured as samples of graphic elements or colors at positions within an image or video frame arranged in a two-dimensional (2D) grid. This is called the spatial domain representation of images or videos. For example, a typical format for an image consists of a stream of samples of 24-bit color graphics arranged in a grid. Each sample is a plurality of components representing a color at pixel units in the form of a grid in a color space such as RGB or YIQ. Various imaging and video systems can be sampled using a variety of different color, spatial and temporal resolutions. Similarly, digital audi...

AI Technical Summary

Problems solved by technology

While a similar continuous zigzag scan pattern is widely used in JPEG and MPEF2 / 4, there is no inherent requirement for the continuity of the scan pattern

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