What is a "JPG" Image?
JPG is the common name1 for the JPEG image format: a format extremely popular, used mainly to save digital photos, which uses a lossy compression algorithm to make image files smaller in exchange of lesser image quality.
Notable Features
JPG Artifacts: because it's a lossy format, every time you open a JPG file and save it again, even if you don't change anything the colors of the pixels of the image will change, creating distortions called "artifacts."
Orientation Header: inside a JPG file, besides the data for the pixels, we also have metadata such as the orientation header. This header describes whether the photo should be rotated by 90°, 180°, or 270° degrees when displayed or not. Thanks to this header, it's possible to rotate the image by these angles without recompressing the pixels, which avoids the creation of JPG artifacts. On the other hand, an unfortunate consequence of this is that some applications that should only view photos without modifying tem began to have the function to modify this specific header in photos in JPG format when you rotate the photo, saving the file without even notifying the user. For example, the "Photos" app in Microsoft Windows does this.
Video:
What does JPG stand for?
JPG is not an acronym. JPG comes from JPEG, which the acronym for Joint Photographic Experts Group, the group that developed the format. The reason we say JPG instead of JPEG is because, traditionally, the extension of a JPEG file would have been .jpeg, but on Windows extensions had to be 3 letters, so the e was removed, and the extension became .jpg, and from this came the name JPG.
The only reason JPG is three characters long as opposed to four is that early versions of Windows required a three-letter extension for file names.
https://www.adobe.com/creativecloud/file-types/image/comparison/jpeg-vs-jpeg-2000.html (accessed 2024-06-05)
Footnotes
- Based on comparisons between "JPG" and "JPEG" on Google Trends and Google Ngram Viewer. ↩︎
Leave a Reply