A first white balance correction amount is calculated according to similarity between image data acquired by an image pickup unit and past image data acquired in the past, and a first white balance correction is performed on the image data according to the first white balance correction amount. A luminance correction amount and a color correction amount are calculated according to similarity between the corrected image data and the past image data corrected in the first white balance correction. Using one of them, the first white balance correction amount is corrected thereby to obtain a second white balance correction amount. According to the obtained correction amount, a second white balance correction, a luminance correction, and a color correction are performed on the image data acquired by the image pickup unit.