The present invention provides an image processor, an image processing method, a program therefor, and a computer-readable recording medium recorded with the program, specifying a region with a high correlation value with a model image with high accuracy regardless of a relative relation of color distribution within the image. A determination object region OBJ consists of a red gradation image 30R, a green gradation image 30G, and a blue gradation image 30B. A CPU section converts a three-gradation-value matrix into a first single data array 40 which is uniquely correlated to a pixel locationin the determination object region OBJ. The CPU section computes a normalization correlation value with a second single data array provided by converting the model image in accordance with the same predetermined rule, and determines whether or not it agrees with the model image according to whether or not the normalization correlation value is over a predetermined threshold.