To automatically extract a profile line in an image largely which differ in luminance value by each piece and has a blurred profile.

This image processor 10 comprises a monochromating means 12 for forming a monochromatic gray scale image b from an original image a; an edge-extracting means 14 for extracting edges from the monochromatic gray scale image b to form an edge extracted image c; a binarizing means 16 for binarizing the edge extraction image c by use of two fuzzy clustering algorithms to form a less profiled binarized image d and a much profiled binarized image e having a large amount of profile, a noise-removing means 18 for removing a noise from the binarized images d and e to form noise- removed images f and g; a thinning means 20 for thinning the noise-removed images f and g to form thinned images h and i; and an interpolation means 22 for interpolating the part having an insufficient profile line of the thinned image h with the profile line of the thinned image i to form one completed image j.