1. An image correction method that provides an image signal with image correction by switching correcting methods according to the image signal, the image correction method comprising: detecting an image area having movement according to the image signal; comparing gradation of image signals corresponding to adjoining pixels; and providing a boundary area of the image area having movement with a diffusion process in an area having gradational change smaller than a predetermined threshold, wherein, the image correction is performed differently between the image area having movement of which the boundary area is diffused and other areas.