Pauli's software -> Terragen resources -> Tips and Tutorials -> Anti-aliasing   p.[1] [2] 19. 11. 2004  
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Anti-aliasing
Page 2: Resampling methods

This page compares different resampling methods: bi-linear, bi-cubic and spline interpolation.

- The same image has been rendered in three sizes: 512 x 512, 600 x 600 and 1024 x 1024, without antialiasing.
- Each image is then resampled to size 256 x 256 with the three resampling methods above.

Click "Zoom 2x" link to see the images in larger size. (This does not download new images, just zooms the existing ones.)

Normal size - Zoom 2x

  Linear interpolation Bi-cubic interpolation Spline interpolation
Rendered size
512 x 512
512x512 Linear 512x512 Bi-cubic 512x512 Spline
Rendered size
600 x 600
600x600 Linear 600x600 Bi-cubic 600x600 Spline
Rendered size
1024 x 1024
1024x1024 Linear 1024x1024 Bi-cubic 1024x1024 Spline

Linear interpolation clearly gives the best results. The higher degree interpolation methods actually increase the aliasing. Bi-cubic is the worst. More advanced Spline method gives somewhat better results, but is still worse than linear interpolation. When reducing the image size, linear interpolation is the best method. Higher degree methods (bi-cubic, spline, Bell filter etc.) are best used when increasing the image size.

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