1. A printer for printing a first image based on supplied first print data on a printing medium, comprising: an image processor for applying predetermined image processing based on a present setting to said entire first print data; and a printer for printing said entire first image based on said first print data subjected to said image processing on said printing medium, wherein: said image processor, when a predetermined operation mode is selected, generates second print data for a frame image obtained by arranging second entire images including an image based on the present setting of several kinds of images obtained by applying image processing settings that are different from each other to said first image, in a predetermined arrangement pattern; and said image processor updates said first image based on the present setting by one of the image processing settings that are different from each other, and generates updated second print data for a frame image obtained by arranging entire images including said updated image based on the present setting and several kinds of images by applying image processing settings that are different from each other in a predetermined arrangement pattern; and said printer prints said frame image based on said second print data on said printing medium.