Deblocking

This filter operates along the 8x8 block edges, on both the luminance and chrominance color planes. It helps to reduce the blocking artifacts caused by the DCT spatial compression algorithm used by the codec.

Blockiness is the most noticeable artifact, so this algorithm is the first one to be applied. The deblocking can be applied on the horizontal and vertical edges (horizontal and vertical deblocking, respectively). The two deblocking methods are applied horizontal first, then vertical. Therefore, at the post-processing level 1, only the horizontal deblocking filter is used (on the luminance blocks), at level 2 both the horizontal and the vertical deblocking filters are used.

No deblocking:


Deblocking: