Video signal processing method and apparatus

摘要

Low frequency components are extracted from a video signal for pixels in a specific area of an image carried by the signal. The low frequency components are allocated, based on luminance components of the signal, to gradations ranging from maximum to minimum levels exhibited by the luminance components, luminance histogram data being produced indicating the frequency of gradations for the pixels. The gradations are allocated to the pixels based on the luminance components to produce high-frequency component histogram data indicating the frequency of gradations for specific pixels each carrying a high frequency component. The luminance histogram data is corrected in accordance with the frequency of gradations in the high-frequency component histogram data to produce corrected luminance histogram data. A gradation correction curve is produced for correcting the gradations exhibited by the signal using the corrected data. The luminance components are corrected based on the correction curve.