Processing for detecting an abnormal pattern candidate embedded in a medical image having been obtained from an image recording operation is performed on an image signal representing the medical image. In cases where the image signal is one which has been subjected to predetermined signal processing, correction processing is performed on the image signal such that the abnormal pattern candidate detecting processing performed on the image signal, which has been subjected to the predetermined signal processing, does not depend upon the predetermined signal processing. The abnormal pattern candidate detecting processing is then performed on the image signal, which has been obtained from the correction processing.