1. An image processing method performed by an image processing apparatus comprising the steps of: inputting into the image processing apparatus image data representing an input image which contains a plurality of face images; detecting with a detector of the image processing apparatus plural face-image areas corresponding to the plurality of face images; calculating with a calculator of the image processing apparatus a ratio of a size of each of the plural face-image areas to an input-image size; setting with a setting section of the image processing apparatus a correcting condition based on the sum of a plurality of ratios of the plural face-image areas calculated in the calculating step; and correcting with a corrector of the image processing apparatus the image data of the plural face-image areas and another image area of the input image data using the correcting condition.