A first correction is executed on target image data representative of a target image when a ratio of a number of first type pixels relative to a number of a plurality of pixels in the target image data is determined to be greater than or equal to a prescribed value. A second correction is executed on the target image data when the ratio is determined to be smaller than the prescribed value. Pixel values of the first type pixels are within a first range that is defined based on a color value indicative of a background color of the target image. The first correction corrects both of internal pixel values and external pixel values which are within and out of a second range that contains the color value of the background color. The second correction corrects the internal pixel values and does not correct the external pixel values.