Disclosed herein are methods of providing an image storage service, computer-readable recording mediums, and/or computing devices. The method of providing the image storage service includes selecting image data in a first format, determining an initial compression parameter for converting the selected image data in the first format into a second format, obtaining primary image data in the second format by transcoding the selected image data in the first format based on the initial compression parameter, searching for a desired compression parameter based on whether image quality of the primary image data satisfies a criterion, obtaining final image data in the second format by transcoding the selected image data in the first format based on the desired compression parameter, and storing final image data in the second format in the memory.