Mitsubishi Semiconductor America, Inc.

Patrick A Sproule

Michael A Mullins

Charles S McFalls, Jr

In the digital processing of video signals, a vertical detail enhancement system is provided that has a transfer characteristic with a transitional region between a coring region and an active region split into three steps. The slopes of the first, second and third step regions are 25%, 50% and 75% of the enhancement gain, respectively. The levels of enhancement in the step regions are set at 25%, 50% and 75% of the level of enhancement in the active region. A vertical detail signal is compared with a coring level selected by a coring multiplexer among a plurality of hardcoded coring levels to set a coring point at the transfer characteristic. Then, the vertical detail signal is successively compared with the coring level incremented by the selected widths of the step regions to control a step choice unit defining a required attenuation of the vertical detail signal value. A paring level is selected by a paring multiplexer among a plurality of hardcoded paring levels.

Vertical detail enhancement with stepped return coring

An 8-to-256 address signal decoder is composed of sixteen 4-to-16 output decoders. Each 4-to-16 decoder is subdivided into eight sub-functions having outputs ANDed together using sixteen OR gates. Each 4-input NAND gate of a conventional rectangular decoder is replaced by two input sub-function NANDs feeding an OR gate. The two sub-function NANDs are positioned outside a high density region, whereas the OR gates reside within a high density region below a memory cell array. The sixteen OR gates are distributed in a 4.times.4 array format. Each OR gate column is four basic cells wide, and there are four output lines for each column of OR gates to conform to dense memory cell layout criteria. The array structure requires only one vertical input line per column and one horizontal input line per row to reach each OR gate. Inverting drivers required to complete the 4-to-16 output decoders are arranged in a 4.times.4 array. The position of each inverter corresponds to the OR gate that drives it.

Growing community of inventors

Raleigh, NC, United States of America

Patrick A Sproule