English: The Difference Between JPG and JPEG

 *Not all image file formats are made equal. Many of them were created to address a problem that an already-existing format could not resolve. The JPEG, for instance, came about because image file sizes were eating up way too much storage space. Note, JIF, JPEG, and JPG file extensions are the same thing. To understand why the file format has so many names, I need to unravel a little bit of the history.  JPEG [Joint Photographic Experts Group] – the file type was named after the sub-committee that helped create the JPEG Interchange Format (JIF) standard. In 1992 by the International Organization for Standardization (ISO). 

*JPEGs are 24-bit still raster images, with eight bits in each channel of the RGB color model. This leaves no room for an alpha channel, which means that while JPEGs can support over 16 million colors.  When an image is saved as a JPEG, the image takes up 50-75% less storage space with little loss in image quality.  JPEG compression is based on a lossy image compression technique called the discrete cosine transform (DCT), which was first proposed by electrical engineer Nasir Ahmed in 1972.

*You can think of a JIF file is as a JPEG in its "purest" form.  But the format isn't used much anymore because it had limitations. The color and pixel aspect definitions of a JIF caused compatibility problems.  Thankfully, these problems were later addressed by other "supplementary" standards that built upon the JIF. The first was the JPEG File Interchange Format (JFIF), and later, the Exchangeable image file format (Exif) and ICC color profiles. 

*Now that JPEG – JFIF is the currently most popular format for storing and sending photo’s on the internet, while JPEG – Exif is that for digital cameras and other image capture devices. Most folks don't know the difference between these and call them both as just JPEG.

*In 2000, the JPEG group released another image file format called the JPEG 2000 (its file extensions are JPG2 and JPF). It was meant to be a surpass the JPEG. Even when it often led to better quality images. The JPEG 2000 file format flopped for a small handful of reasons. It was based on an entirely new code and thus wasn't backward compatible with the JPEG. And JPEG 2000 files required more memory to process, which was a a deal-breaker back then. After all, the average computer at the time had only about 64 MB of memory. 

*JPEG 2000 has seen a bit of a resurgence now that computer hardware, in general, has vastly improved over the last 35 years, but the file format is still very much underused. The only internet browser that has support for JPEG 2000 files now is Safari.

*Early versions of Windows had a maximum 3-letter limit when it came to the length of file extensions. JPEG had to be shortened to JPG as to not exceed the limit. Mac and Linux computers never had such a thing, and so users would continue to save images as JPEG.

*Popular image editing programs that worked across different operating systems—such as Photoshop and Gimp—would eventually set their default JPEG file extension to JPG in an attempt to minimize confusion.  And that's how we ended up with two file extensions for the same format: JPEG and JPG. There is no difference between them.

*The better of the two JPEG vs. PNG: the JPEG and the PNG were released within the same decade, with each resolving a different digital image problem that the technology world faced back then. You could say that it's only natural that they are constantly compared... and they are, even to this day.

*Between JPEG and PNG, which image file format reigns supreme? The answer depends on what kind of image you're saving.  JPEGs are better suited for photographs because they utilize lossy compression to keep to reasonable file sizes. Photographs are such big, detailed images that compression artifacts aren't very noticeable on them.  On the other hand, images with sharp points, crisp edges, and with large areas of one color don't look quite right when saved as a JPEG.

*This is where the Portable Network Graphics (PNG) file might come in.  Developed by the PNG Development Group four years after the release of the JPEG, the PNG supports lossless data compression and transparency. PNGs are thus often used if image quality must be retained and file size is not an issue. 

*Here is a good rule of thumb is keeping JPEG to photographs, and saving PNG for images with transparency and non-photographic images.  JPEG and JPG Are the Same File Format:  Despite the confusion the JPEG has caused with its many updates and variations, the eventual flood of digital images on the internet in the mid-90s was caused by its release. So, the next time you're ready to export a photo from an image editor and are presented with the long list of available formats, just remember: JPEG and JPG are one and the same.

As always, stay informed, and be safe!

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