With the explosion of scanners, digital cameras, and the World Wide Web, the JPEG image format has quickly become the most widely used digital image format. It is also the most misunderstood. Here are some common misconceptions and facts.
Image file formats – JPEG, GIF, PNG
Although the files often end with the three-letter extension JPG or JP2 for JPEG 2000, the file format is spelled JPEG. It is an acronym for Joint Photographic Experts Group, the organization that developed the format.
Simply opening or viewing a JPEG image will not harm it in any way. Saving an image repeatedly during the same editing session without ever closing the image will not cause any loss of quality. Copying and renaming a JPEG will not cause any loss, but some image editors recompress JPEGs when the "Save As" command is used. To avoid further loss, duplicate and rename JPEGs in a file manager rather than using "Save as JPEG" in an editing program.
Opening, editing, and re-saving a JPEG image will result in additional image degradation. Minimize the number of editing sessions between the first and final versions of a JPEG image. If you need to perform editing functions in multiple sessions or in multiple different programs, use a non-lossy image format such as TIFF, BMP, or PNG for the intermediate editing sessions before saving to the final version. Repeated saving within the same editing session will not cause additional degradation. It will only occur when the image is closed, reopened, edited, and re-saved.
