1. An image processing apparatus comprising: an input unit configured to input image data including m frame images per unit time; a generating unit configured to generate a high-frequency component emphasized frame image and a low-frequency component frame image from each frame image included in the input image data, wherein the high-frequency component emphasized frame image is generated by subtracting the low-frequency component frame image from the corresponding frame image; a correction unit configured to correct, for only the low-frequency component frame image, which is generated by said generating unit, a luminance corresponding to each frame image at a predetermined ratio applied to the entire frame so as to make the image data perceptible in the same brightness as that of each of the frame images output as the m frames per unit time; and an output unit configured to alternately output the high-frequency component emphasized frame image generated by said generating unit and the low-frequency component frame image whose luminance has been corrected by said correction unit as image data including 2 m frame images per unit time.