A method to control a computer is provided. The computer executes steps of designating the image data file, generating locator information to indicate a location of a corresponding storage folder based on a unique identification of the image data file, and creating the corresponding storage folder having the locator information, which indicates a location of the storage folder, as a folder name. Also, the computer may execute steps including making a copy of the designated image data file having the unique identification and the file name, storing the copied image data file in the corresponding storage folder created in the creating step, and deleting the copied image data file and the corresponding storage folder created in the creating step when the designation of the image data file is invalidated.