This invention can perform a developing process or editing process, with a high response, for raw image obtained by image sensing by a digital camera or the like. When, therefore, raw image data is input, an extraction area in the raw image data is determined on the basis of the size of an image display area in which a processed image is displayed and a magnification set at this time. A developing process is then performed for partial raw image data in the determined area, and the resultant data is displayed in the image display area.