AUTOMATIC LUMINANCE ADJUSTMENT DEVICE AND METHOD

摘要

A predetermined test signal of constant luminance is inputted, and luminance values of the A/D-converted signal are accumulated for the area of a predetermined screen region. Then, the luminance level of the test signal before A/D conversion is adjusted so that the luminance value obtained by dividing the accumulation result by the number of values added becomes a desired value. Alternatively, after inputting the predetermined test signal of constant luminance, the luminance level of the test signal before A/D conversion is adjusted so that the video start coordinate value and the video end coordinate value detected from the luminance level of the A/D-converted signal agree with the ideal coordinate values determined from the test signal wave form. Further alternatively, without using the test signal, the video start coordinate and the video end coordinate are detected by comparing the A/D-converted luminance level of an inputted analog video signal with the full scale of the output of an A/D converter, and the luminance level of the analog video signal before A/D conversion is adjusted so that the difference between the detected video start coordinate and video end coordinate becomes minimum. Accordingly, optimal luminance adjustment can be carried out.