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Method of Implementing a 4x4 Texture Filter Leveraging Existing Hardware of a 2x2 Filter

IP.com Disclosure Number: IPCOM000009391D
Publication Date: 2002-Aug-20
Document File: 2 page(s) / 74K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method that uses a set of four spatially adjacent 2x2 filters to implement a 4x4 texture filter. Benefits include simplifying the implementation process, as well as saving die area.

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Method of Implementing a 4x4 Texture Filter Leveraging Existing Hardware of a 2x2 Filter

Disclosed is a method that uses a set of four spatially adjacent 2x2 filters to implement a 4x4 texture filter. Benefits include simplifying the implementation process, as well as saving die area.

Background

Current graphics processors support bilinear filtering, in which a 2x2 block of texels is read from the source map and blended to write to the destination pixel. In addition, a 4x4 filter has been implemented which reads 16 texels from the source map. Specialized hardware to fetch 4x4 texel blocks is expensive, and duplicates much of the hardware functionality used to fetch 2x2 texel blocks.

General Description

To reduce changes to the hardware, the disclosed method uses a set of four spatially adjacent 2x2 filters; this avoids changes to much of the graphics pipeline, saving implementation effort as well as die area.

Figure 1 shows four 2x2 filters combined to form a 4x4 filter. The violet “X” shows the pixel mapping point to the texture map, and the four red “X”s show the four derived pixel mapping points, which are inserted into the pipeline to fetch the four 2x2 filters for the bilinear filter.

Figure 2 shows that the middle of the pipeline is left unchanged by the addition of the 4x4 filter capability.

Advantages

Some implementations of the disclosed structure and method provide one or more of the following advantages:

The disclosed method simplifies the implementation p...