1. A visual processing device that performs gradation processing with respect to each image region of an image signal that has been received as input, comprising: gradation transformation property derivation unit operable to derive a gradation transformation property of a target image region that is to be subjected to the gradation processing, by using surrounding image data of at least one surrounding image region, which is an image region that is positioned proximal to the target image region and which includes a plurality of pixels; and gradation processing unit operable to perform gradation processing of the image signal of the target image region based on the gradation transformation property that has been derived.