To provide an image signal processing apparatus which improves a good sense of contrast with making a remarkable object recognizable.

The apparatus includes a screen division controller 101 to divide a screen of one frame, a histogram calculator 102 to calculate a histogram each divided block, a block histogram storage portion 108 to store the calculated histogram, a similarity degree calculator 103 to calculate a similarity degree of the histogram each block, a similarity degree storage portion 104 to store the calculated similarity degree, a weighting coefficient multiplier 105 to calculate a weighting coefficient from the similarity degree and to multiply it by the histogram of the block corresponding to it, a whole histogram calculator 106 to calculate a whole histogram by adding all of the calculated histograms, a gamma curve generation portion 107 to generate a gamma curve based on the calculated histogram and a stored gamma curve, and a gamma correcting portion 109 to conduct a gamma correction to an image signal by using the generated gamma curve.

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