The invention provides a method of processing an image in a diagnostic apparatus of diagnosing a cutaneous lesion using a cutaneous image, comprising the steps of: (a) obtaining a first detail image made by performing a first component separation filter on a brightness component of the cutaneous image; (b) obtaining a second detail image made by performing a second component separation filter on the brightness component of the cutaneous image, the second component separation filter having properties different from those of the first component separation filter; (c) generating a third detail image based on the first detail image and the second detail image; (d) newly generating a third base image based on the third detail image; and (e) combining the third detail image with the third base image to restore a brightness component and generate a highlighted image.