There is disclosed an image processing program causing a computer to perform the following operations setting image processing executed for a processing target image as application image processing, setting a plurality of predetermined processing parameter values used in the application image processing, executing the application image processing based on the parameter values to generate a plurality of processing result images, generating reduced images of the processing result images, displaying the reduced images, selecting one of reduced images, deciding the processing parameter values of the processing result image corresponding to the selected reduced image as a processing parameter values of the application image processing, setting the processing result image corresponding to the selected reduced image as a new processing target image, setting another kind of image processing as new application image processing, and repeatedly executing the process from the parameter setting processing to the image processing setting processing.