Review: ATI's Radeon X800 XT Platinum Edition - Graphics - HEXUS.net

Texture Filtering Image Quality - 4X, 8X and 16X aniso

Texture filtering image quality is analysed to make sure it's up to par with what the hardware is supposed to be capable of.

4X anisotropic filtering

FilterTest - High Quality - 4X Aniso - Click for full size .png (~1MB)

Serious Sam - High Quality - 4X Aniso - Click for full size .png (~2.4MB)

90 and 45° angles are those filtered at full 4X with everything else receiving 2X.

8X anisotropic filtering

FilterTest - High Quality - 8X Aniso - Click for full size .png (~1MB)

Serious Sam - High Quality - 8X Aniso - Click for full size .png (~2.4MB)

The angle adaptive nature of ATI's filtering algorithm is most evident in the following 8X and 16X modes, with the flower-like shape giving the game away. Easy angles for the hardware to calculate are filtered most aggressively.

16X anisotropic filtering

FilterTest - High Quality - 16X Aniso - Click for full size .png (~1MB)

Serious Sam - High Quality - 16X Aniso - Click for full size .png (~2.4MB)

See above.

Summary

If R420's aniso algorithm has been changed from what's present on R360, I can't spot it. Its angle adaptive, which is somewhat suboptimal in terms of maximum possible image quality, but that maximum image quality is something that even R420-class hardware doesn't attempt at speed. Angle based aniso is needed for both good image quality and playable or usable framerates. It's a scheme adopted by NVIDIA for NV40, so all competing hardware in this class does the same thing.