An image processing method for subjecting captured-image data outputting from an image-capturing device to an optimization processing for appreciation to produce viewing image referred image data. The image processing method has the step of conducting a pre-processing before the optimization processing is carried out, wherein the pre-processing includes the transformation of the frequency characteristic of the captured-image data into the scene-referred frequency characteristic by removing the effect of a frequency characteristic specific to the image-capturing device from the frequency characteristic of the captured-image data.