De-emphasis filter with integrated determination of achromatic values

Abstract

A digital de-emphasis filter for a SECAM decoder for converting a sequence of input image data into filtered image data includes at least one recursion register for storing an auxiliary value that is obtained using an input image data value. An arithmetic circuit uses the auxiliary value and a newly input image data value to generate a new auxiliary value, which replaces the contents of the recursion register, and a filtered image data value. To determine the achromatic value in addition to performing de-emphasis filtering, the filter is provided with a device for storing and outputting a value representative of an estimated value of the achromatic value of the SECAM signal, and a first switch for applying and registering the output estimated value into the recursion register at the beginning of each burst gate period of the SECAM signal. The arithmetic circuit uses the registered estimated value and at least one value of the burst signal to output an estimated value that is updated using this burst signal value.

Dependencies are inferred from the claim text.