1. An image processing device comprising: a display unit that displays an image; a reduced-image creating portion that creates a reduced image from an original image; a reduced-retinex-image forming portion that calculates reflectance of each pixel in the reduced image based both on a pixel value of a subject pixel in the reduced image and on a peripheral average luminance of the subject pixel, thereby forming a reduced retinex image that is configured of reflectance of each pixel in the reduced image; a normalizing-parameter setting portion that obtains frequencies of the reflectance in the reduced retinex image and that sets an upper limit and a lower limit for normalization; a reduced-image correcting portion comprising: a first normalizing portion that normalizes the reflectance of the reduced image based on the upper limit and the lower limits thereby obtaining a normalized reflectance for each pixel in the reduced image; and a first correcting portion that corrects the reduced image based both on the normalized reflectance and on the pixel value for each pixel in the reduced image, thereby obtaining a corrected reduced image; a preview-image displaying portion that displays the corrected reduced image on the display unit; and an original-image correcting portion comprising: a retinex-image forming portion that calculates reflectance of each pixel in the original image based both on a pixel value of a subject pixel in the original image and on a peripheral average luminance of the subject pixel; a second normalizing portion that normalizes the reflectance of the original image based on the upper limit and the lower limit, thereby obtaining a normalized reflectance for each pixel in the original image, and a second correcting portion that corrects the original image based both on the normalized reflectance and on the pixel value for each pixel in the original image, thereby obtaining a corrected original image.