To easily and fast search a reference image from in an input image as to an image processor, which searches a specified reference image from an externally supplied input image, and a medium where the image processing program for actualizing the processor by using a computer.

The image processor, which searches, from the given input image, the specified reference image, is equipped with a reference means 1, which previously stores a frequency distribution Sρθ in a ρθ Hough space found by processing and input image by Hough transformation, a Hough transforming means 2, which transforms the input image into the frequency distribution Tρθ in the ρθ Hough space by Hough transformation, and a search means 3 which decides the correlation between the said frequency distribution Tρθ and frequency distribution sρθ and judges 'whehther or not a reference image in the input image' from whether or not they correlate to each other.