Patent ID: 7492964

Claim:
A computer readable storage medium storing instructions of a computer program which when executed by a computer results in performance of steps comprising: inputting a first image and a second image from two cameras, respectively; transforming the first image to a transformed image on a basis of image transform which is introduced from a geometrical relationship between a reference plane on which an obstacle is positioned in a field of view common to the two cameras, and the two cameras for transforming any given pixel in a reference plane region in the first image to a corresponding pixel in the second image; obtaining a degree of similarity D indicating a similarity between an image in a processing region established in the second image and an image in a corresponding processing region established in the first image and being a function of position in the vertical direction of the image; establishing, when any given image line in a specified region in the second image is a contact line of the obstacle with the reference plane, the processing region for an inter-image arithmetic operation between the first image and the second image, and a plurality of the processing regions being established with the image line being shifted in the vertical direction; obtaining a degree of similarity P indicating a similarity between an image in the processing region established in the second image and an image in a corresponding processing region established in the transformed image and being a function of position in the vertical direction of the image; establishing the processing region for an inter-image arithmetic operation between the second image and the transformed image, and a plurality of the processing regions being established with the image line being shifted in the vertical direction; detecting the obstacle on a basis of the degree of similarity D and the degree of similarity P on a reference plane region; obtaining a difference K between the degree of similarity D and the degree of similarity P both obtained as being on the reference plane region; judging that the obstacle is at a position where the difference K is large; and determining a width and a height of the processing region on the basis of a position in the vertical direction on the second image.