Patent ID: 7893917
Filing Date: 2011-02-22
Classification: G09G

Abstract:
1. An image display apparatus comprising: an image display which includes a light source whose light-source luminance is adjustable; a light modulation device that displays an image by modulating a transmittance or a reflectance of light from the light source, based on signals representing the image; a histogram creation unit configured to create a histogram from one frame of an input video image, the histogram indicating frequencies of pixels included in level-ranges associated with representative gray-scale levels; a light-source-luminance calculator which includes: a difference calculation unit that calculates differences between first brightnesses, each predetermined for the each representative gray-scale level, and second brightnesses, each preliminarily obtained for the each representative gray-scale level displayed on the image display with each of a plurality of light-source levels of the light-source luminance; a difference accumulating unit that accumulates, for each of the representative gray-scale levels, products of the differences by the frequencies of pixels included in level-ranges associated with representative gray-scale levels; a light-source-luminance selection unit that selects a light-source level having the smallest accumulated sum or the smaller accumulated sum than a threshold value; and a control unit configured to provide signals of the one frame of the input video image to the light modulation device and control the light modulation device so that the light source emits light in luminance corresponding to the selected light-source level.