Ermittlung mittlerer Luminanzpegel in verschiedenen Bereichen eines Videobildes und darauf beruhende automatischen Erkennung des Bildformates

摘要

A high precision aspect ratio auto-discrimination apparatus used for display apparatuses and television receivers comprising: an apparatus for detecting the upper edge and lower edge of a letter box picture through detecting the average luminance of every horizontal scan period; an apparatus for detecting respective average luminance levels in a plurality of specific regions in one field picture controlled by a horizontal synchronous signal and a vertical synchronous signal; and, an aspect ratio discrimination section to which the outputs of said both apparatuses are input.