IMAGE LUMINANCE DETECTION AND CORRECTION EMPLOYING HISTOGRAMS

摘要

A display system (10) employs histograms to detect an active video region (2) of a video frame (1). A microcontroller (16) loads registers (27) to accumulate histograms of low pixel values occurring within columns (70-74) of video data. The microcontroller scans the histograms to identify the left-most column in which a set (80) of black pixels are clustered, thereby marking the left edge of the active video region. The right edge is similarly detected. An ADC (24) digitizes the video signal and any overshoot and noise causes many pixels to be converted to below their maximum values. Therefore, a histogram (90) of the highest pixel values is collected from the active video region. The microcontroller scans the histogram to locate a rapid decrease in the number of pixels exceeding some large value. The microcontroller remaps the upper range of data to the maximum value, thereby enhancing image brightness.