The story starts in the mid‑1980s, when digital images were huge, storage was tiny, and bandwidth was limited to consumer grade 56Kb modems. Two major standards bodies—ISO/IEC and the CCITT (now ITU‑T)—each had their own image‑coding groups working on the problem. Eventually, they joined forces and created the Joint Photographic Experts Group in 1986 to develop a universal compression standard.

JPEG’s magic came from a mathematical technique proposed in the 1970s called the discrete cosine transform (DCT) that could reduce image data while keeping the important visual information intact.  

The DCT compression process starts with reading the values of a 8 by 8 box of pixels. A single number is calculated that represents those pixels. This process is called Quantization. The initial JPEG protocol just had that 64 to 1 reduction ration. As the years went by the protocol was updated to include a variable nature or higher Quantization. Instead of an 8X8 box, you can make it 10X10 or 20X20 or more. this resulted in smaller file sizes at the cost of image detail. We see this in our software today as a slider, percentage or some quality level.

The result is a single value that represented that 8 by 8 (or higher) box of pixels. What started as 64 (or more) different values now is represented as a single value.  This continues through all the pixels.

Then a proven data compression tool that is used for ZIP files, a Huffman algorithm, is applied and that compresses the file even further. The file is saved and today we know this as the JPEG or JPG file.

The actual software code that does all of this was developed at the same time the proposal was circulating and when completed in October 1991, it was made free and published as Open Source to aid rapid and wide adoption under the name “libjpeg”.  Any programmer could now incorporate that library into their own programs to aid in displaying images, creating and saving images.

The JPEG committee spent the late ’80s refining this into a practical, flexible compression method. By 1992, the first official JPEG standard was published.

ISO/IEC and the Formal Standard

JPEG isn’t just a format—it’s a full international standard known as ISO/IEC 10918‑1, also published as ITU‑T T.81. While the standard was being developed. Another standard was also being worked on that would define how JPEG images travels across the internet. Published as part of the MIME (Multipurpose Internet Mail Extensions) standards, RFC 2046 assigns JPEG the official media type image/jpeg, which tells browsers, email clients, and servers how to handle JPEG files. Without RFC 2046, JPEGs wouldn’t have had a consistent, universal identity online.

Why It Mattered

JPEG’s arrival changed everything:

• It made digital cameras practical
• It made photo‑heavy websites possible
• It made sharing images over slow connections tolerable
• It became the default format for billions of images per day

Even today—despite newer formats like JPEG 2000, HEIC, and AVIF—plain old JPEG remains the most widely used image format in the world. Its combination of efficiency, simplicity, and compatibility has kept it alive for more than three decades.

The Bottom Line

JPEG wasn’t just introduced, it was engineered, standardized, and launched by a global coalition of experts who solved one of early digital media’s biggest problems. Thanks to the Joint Photographic Experts Group, ISO/IEC, and the internet‑side support from RFC 2046, photographers everywhere gained a format that balanced quality and file size in a way that still shapes digital imaging today.

The JPEG compression works by transforming an image into a form where redundant or visually insignificant information can be removed, then encoding the remaining data efficiently. The process is lossy, meaning some information is permanently discarded to reduce file size.  Imagine you have a big, colorful picture made of millions of tiny dots (pixels). JPEG’s job is to shrink that picture so it doesn’t take up so much space, without making it look too different.

This made a significant difference. Some early digital cameras ONLY stored JPEG files to their memory cards because storage was expensive and the RAW format was unique to every manufacturer.  Software to manipulate images existed since the mid 1980’s and primarily used image formats that existed already.

• PCX (1985) — ZSoft PC Paintbrush’s native format.
• TIFF (1986) — Aldus Corporation; became the standard for professional publishing.
• BMP (1987) — Microsoft Windows device‑independent bitmap.
• GIF (1987) — CompuServe; 256‑color indexed images with LZW compression.
• MacPaint (1984) — Apple’s original Macintosh bitmap format.
• GEM Bit Image (1980s) — Digital Research GEM graphics environment.
• Sun Rasterfile (1980s) — Sun Microsystems workstation raster format.
• Truevision Targa (TGA) (1984) — Truevision; popular in video and early PC graphics.
• IFF/ILBM (1985) — Amiga Interchange File Format / Interleaved Bitmap.
• XBM (X Window Bitmap) (1980s) — X11 bitmap format.
• XWD (X Window Dump) (1980s) — X11 screen dump format.
• WordPerfect Graphics (1980s)

When the JPEG format was formalized as an international standard, the other image formats that were created and sponsored by individual businesses could not compete and eventually faded away with a couple of exceptions. As this new image compression format was emerging, software was being developed and sold based on the information in the RFC.  All of the software that worked with this image format is integrated into the software that we use today.  For the most part companies either sold their entire tools, or were merged with other companies.

• 1987 — Digital Darkroom (Silicon Beach Software)
• 1985 — Deluxe Paint (Dan Silva / Electronic Arts; Amiga release)
• 1988 — Adobe Photoshop (license/distribution begins; Photoshop name established)
• 1990 — Adobe Photoshop 1.0 (Feb 19, 1990)
• 1991 — Adobe Photoshop 2.0 (June 1991)
• 1991 — Aldus PhotoStyler (released June 1991)
• 1992 — Kai’s Power Tools (KPT) (created in 1992)
• 1992 — Paint Shop Pro (first version “Paint Shop”/1.0—early 1992)
• 1994 — Adobe Photoshop 3.0 (layers introduced; Sep 1994 on Mac)
• 1996 — GIMP (first public release v0.54, Jan 1996 / first public release)

All images share a height and width that is typically measured in pixels.

The JPEG image format has its place firmly entrenched in the modern world. It is in every image you see on the web and in email.

Today’s smartphones primarily use JPEG image format with sufficient quality to see or send to a printing service. Web sites operate efficiently, computer system wallpaper and display themes don’t take a lot of memory space to be useful.  The JPEG image standard is one of the foundational legs of the modern Internet and will remain that way for the future, because it’s free and open source.

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