Rank Identification for an Analog Ranked Order Filter

Abstract

The paper suggests a method for rank identification from a previously reported programmable parallel current-mode analog ranked order filter circuit. This allows the input direction with any selected rank to be indicated as well as extracting the correct value from a set of input currents. The rank identification can be implemented with only O(n) increase in circuit complexity. This addition can be used to avoid errors caused by device mismatch and may also result in new application methods for the ranked order filter. Programmable ranked order filtering can be used for many image processing tasks such as mathematical morphology and median filtering.