Verfahren zur Rauschverringerung in Bildsignalen mehrerer Gradationen.

摘要

A multi-gradation image signal obtained by multi-gradationisation of a signal obtained by reading through a CCD (1) on original having a half tone is supplied to an unsharp signal producing part (5), which in turn outputs an unsharp signal (SU) produced from the multi-gradation image signal and the multi-gradation image signal (SS) itself. A comparator (12) discriminates a shadow portion of the original by comparing the multi-gradation image signal (SS) with a reference value. As a result, a signal which is unsharp in the shadow portion of the original is produced from the multi-gradation image signal (SS) and the unsharp signal (SU).