Texture compression
Texture compression is used in computer graphics to reduce the memory and bandwidth requirements of textures .
conditions
The requirements for texture compression systems differ from those for ordinary image compression , as fast access to random texels is required:
- Fixed compression rate to simplify address calculations
- Few indirections because of the long pipelines in graphics chips
- Compatibility with texture caches, i.e. H. Preservation of the locality
- Simple, faster, and easy to implement in hardware decompression algorithm (on the other hand, the compression algorithm can be very complex)
Systems
In the early days, vector quantization , especially indexed colors, was used, but this was replaced by other methods because of the indirection that occurred. Indexed colors were used for a long time in the area of embedded systems and were part of OpenGL ES 1.x.
Most widespread on the desktop is S3 Texture Compression (S3TC) , which is included in DirectX and supported in OpenGL via an extension .
The ETC developed by Ericsson is widespread in high-end smartphones .
FXT1 was a texture compression system from 3Dfx . It is only supported by Intel today .
Web links
- Texture compression survey (PDF) (1.35 MB)
- Slides of a lecture about texture compression (PDF) (1.36 MB)