New or significantly changed skin lesions are detected by providing digital baseline image data of an area of a subject's skin by placing a calibration piece on the area and then positioning a digital camera to frame the area within a field of view of the camera and digitally photographing the area to produce a digital baseline image of the area. The digital baseline image is downloaded from the camera to a computer, which digitally filters the baseline image to produce a partially transparent baseline image scaled to fit over a viewfinder display of the camera. The filtered baseline image is printed on a transparent sheet to produce template. Substantially later, a calibration piece is placed on the area, and the template is placed over the viewfinder display of the camera. The camera is positioned to frame that area within the field of view so as to align a live image of the area with the baseline image on the template. The area is photographed to produce a digital current image thereof. The current image is downloaded to the computer, which is operated to alternately display the aligned current image data and the baseline image data to allow visual identification of lesions which changed enough in the "alternating image comparison display" to identify a new or significantly growing lesion.