A method of compressing an original dynamic range of an original image, includes a first step of obtaining a reduced image corresponding to the original image by performing quantization and downsampling on the original image that has been input; a second step of calculating a look-up table based on the reduced image, wherein the look-up table indicates a mapping relationship between the original dynamic range of the original image and a dynamic range of a medium; and a third step of mapping each of the pixels in the original image from the original dynamic range of the original image onto the dynamic range of the medium based on the look-up table.