1. An image processor comprising: a high-frequency component detecting unit that detects high frequency components contained in image data by calculating a convolution for a pixel or a pixel group of the image data, to output the detection result; a smoothing unit that smoothes the image data, to output the smoothed image data; and an image data processing unit that combines the image data with the smoothed image data at a combination ratio determined from the detection result, to output the combined image data.