Patent ID: 8620076

Claim:
A region extraction apparatus, comprising: an image acquisition device that acquires an image; a temporary initial region specifying device that specifies a plurality of temporary initial regions in the acquired image; a separation calculation device that calculates a separation that is an indicator indicating how much pixel values of all pixels of an inside of a specified temporary initial region and pixel values of all pixels of an outside of the specified temporary region are different from each other, on each temporary initial region; an initial region specifying device that specifies a temporary initial region having a highest calculated separation as an initial region; and a region extraction device that performs a region extraction on a basis of the specified initial region, wherein the separation calculation device includes: a histogram generation device that generates a first normalized histogram whose abscissa represents pixel values on a basis of the pixel values of all the pixels inside of the specified temporary region and a second normalized histogram whose abscissa represents pixel values on a basis of the pixel values of all the pixels outside of the specified temporary initial region; and a device that calculates a total sum of absolute values of differences between the first and second normalized histograms on a pixel value basis, as the separation.