Frame buffer compression and decompression method for graphics rendering

Abstract

Methods and apparatus are disclosed for the processing of frame buffer data, such as color buffer data, in graphics processing applications. Although more generally applicable, these methods and apparatus are particularly useful in real-time, polygon-based, 3D rendering applications. An exemplary method for processing graphics data according to one or more embodiments of the invention begins withthe retrieval, from a buffer, of pixel values corresponding to a tile of two or more pixels, and with the updating of one or more of those updated pixel values. The updated pixel values are selectively compressed using a lossy compression operation or a lossless compression operation, based on an accumulated error metric value for the tile. If lossy compression is used, then the accumulated errormetric value for the tile is updated; in either event, the compressed pixel values are stored in the frame buffer for further processing. With this approach, the accumulated error caused by successive, or tandem, compression operations may be limited to a pre-determined maximum.

Description

Background technique [0001] The present invention relates generally to processing of graphics data, and in particular to methods and apparatus for compressing framebuffer data in a three-dimensional (3D) graphics rendering system. [0002] Typically, 3D graphics rendering systems utilize several memory buffers such as texture buffers, depth buffers (often referred to as z-buffers), and color buffers during the rendering process. These buffers are often stored in random access memory (RAM) external to the graphics processing unit (GPU), which may house a relatively small cache memory. Because buffered data can be fetched and rewritten many times during the rendering process, memory bandwidth (capacity used to write data to memory and read data from memory) must usually be quite high, especially to support real-time applications such as real-time games. graphics processing applications. On a desktop personal computer, the available memory bandwidth can be very high, on the ord...

AI Technical Summary

Problems solved by technology

If the pieces of data are compressed each time using lossy compression, this concatenated compression can result in repeated loss of information, introducing unacceptable errors into the final data

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