“Block effect”prevalent in transform encoder images becomes increasingly objectionable as the required bit rate is reduced. The perceptual effect of this coding noise is highly dependent on the local behavior of the signal upon which it is superimposed

this coding noise can be divided three parts: Staircase noise

Grid noise

Texture noise. At first

we analyze why and how the“block effect”appears

and the measure of the "block effect". Then

we propose a processing algorithm named“adaptive block boundary average”and a computationally-efficient edge classifier which is the basis of a non-linear shift variant post-processing algorithm incorporating average filter and median filter.