Matsushita Electric Industrial Co., Ltd.

Hiroaki Satou

Hiroshi Miyai

Tsutomu Muraji

Tetsuro Shiota

An image display device has a first look-up table memory ( ) for correcting a gamma curve of an input video signal so as to correct a gradation of a display image, a second look-up table memory ( ) for generating uniformity correction data on a screen at each gradation level, and a positional information generating portion ( ) for generating uniformity correction data corresponding to a position on the screen. A correction data making portion ( ) synthesizes the uniformity correction data output from the second look-up table memory ( ) and the uniformity correction data output from the positional information generating portion ( ). An arithmetic processing circuit ( ) corrects the video signal that has been subjected to the gradation correction and read out from the first look-up table memory ( ) by using the uniformity correction data output from the correction data making portion ( ), and the uniformity correction of the display image is performed at all gradation levels.

Image display

A gamma correction and white balance adjustment device has a calculator for calculating brightness target values expected to produce on a screen in response to calculated input signals to be applied to a CRT. The calculated input signals are actually applied to the CRT and the actual brightness values observed on the screen are measured. A table of a list of the calculated input signals expected to produce the brightness target values and a corresponding list of measured input signals which actually produced the calculated brightness target values is formed. An amplitude conversion circuit is provided for converting the amplitude of the input signal, which is equal to the calculated input signal, to that of the measured input signal in accordance with the obtained table.

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Hyogo, Japan

Hiroaki Satou