Abstract: The present invention relates to a method of compressing an image, for maintaining an image format, and providing an image having a high compressibility while minimizing image quality degradation for an original image regardless of the image format. The method of compressing an image embodied in a computing device according to an embodiment of the present invention includes: a file format determination step of determining whether a file format of an original image is a lossy compressed image, a lossless compressed image, or an uncompressed image; an image block division step of dividing the original image into a plurality of image blocks; and an image conversion step of converting the original image in a different manner according to the file format of the original image.