Padding

Padding is an important feature of HTTomo when performing computations on Chunks and Blocks. If the method is a 2D method (work with 2D frames), e.g., a denoising filter, then the data does not require any padding as the boundary conditions between blocks will not be violated. However, when the method is a 3D method and it works with 3D volumes, then in order to satisfy boundary conditions and avoid artefacts, one needs to pad blocks.

How this can be useful?

It is useful because when padding feature exists one can use true fully 3D methods which provide a consistent resolution in all three dimensions, see the image below. Because of the access to 3D data, one can perform better in removing artefacts, improving contrast, etc.

Fig. 18 2D denoising applied to 3D data, note the resolution inconsistency in the vertical direction.

Fig. 19 3D denoising applied to 3D data. The resolution is consistent in all three dimensions.

Note

With padding enabled, HTTomo can perform more state-of-the-art filtering techniques as well as advanced iterative reconstruction in 3D.