JPEG (Joint Photographic Experts Group) is a widely used image format designed specifically for storing and transmitting digital images. It uses lossy compression to reduce file sizes while maintaining acceptable image quality. This format is particularly effective for photographs and complex images with gradual transitions of tone and color.

Note: JPG and JPEG are exactly the same format. The only difference is the number of characters used in the extension.

• .jpg
• .jpeg
• .jpe
• .jfif
• .jp2 (JPEG 2000)
• .j2k (JPEG 2000)
• .jpx (JPEG 2000)
• .jxr (JPEG XR)
• .hdp (JPEG XR)
• .wdp (JPEG XR)
• .jxl (JPEG XL)
• .mjpeg (Motion JPEG)
• .mjpg (Motion JPEG)
• .jfi
• .jif

JPEG file belongs to the “Image File” category. It is a compressed, pixel-based image format which also makes JPEG a type of “raster graphics” with “compressed image storage”.

Most applications that deal with pictures support JPEG image files.

• Adobe Photoshop
• Microsoft Paint
• GIMP
• Web browsers
• Most image viewers
• Mobile photo apps
• Operating system default viewers

The Joint Photographic Experts Group developed the JPEG format. This group constitutes the collaboration between ISO (International Organization for Standardization) and IEC (International Electrotechnical Commission).

JPEG project began in 1986. JPEG standard (ISO/IEC 10918-1) was first released in 1992. JPEG File Interchange Format (JFIF) was standardized in 1994. The less widely adopted JPEG 2000 was introduced in 2000.

Maximum File Size

• The theoretical limit is 65,535 × 65,535 pixels
• The practical limit depends on available system memory
• The common maximum is 30,000 × 30,000 pixels

Color Depth

• Up to 24-bit color (16.7 million colors)
• 8 bits per color channel (Red, Green, Blue)
• Grayscale support: 8 bits (256 levels)

Resolution Limits

• No inherent resolution limits
• Typical web resolution is 72-300 DPI
• Print resolution is around 300-600 DPI
• Maximum quality is based on the original image

For Images

• image/jpeg
• image/jpg
• image/jp
• image/pjpeg
• image/pipeg
• image/vnd.swiftview-jpeg
• image/x-xbitmap

For Application

• application/jpg
• application/x-jpg

It supports binary format of two types

• JPG/Exif: It is used by Camera, Image capturing devices etc.
• JPG/JFIF: It is used on World Wide Web

• Header Hexadecimal Signature: FF D8 FF
• Footer Hexadecimal Signature: FF D9

JPEG/JPG has plenty of advantages over other image formats:

• Small file sizes
• Wide compatibility
• Excellent for photographs
• Supports millions of colors
• Fast loading times
• Efficient storage
• Universal support

• Lossy compression
• Quality degrades with each save
• No transparency support
• Not ideal for text or sharp edges
• Compression artifacts
• Limited for professional editing

JPEG is most commonly used for digital photography, web graphics and document storage. Some examples are as follows:

Digital Photography

• Personal photos
• Professional photography
• Online galleries

Web Graphics

• Website images
• Social media posts
• Email attachments

Document Storage

• Scanned documents
• Digital archives
• Photo documentation

Q1. What is the difference between JPG and JPEG?

JPG and JPEG are the same format. JPG was created for Windows systems that required three-letter extensions. So .jpeg was not permitted. Hence .jpg was adopted and has become a standard. Both JPG and JPEG are interchangeable.

Q2. Why do JPEG files lose quality?

JPEG files lose quality due to their lossy compression algorithm. It removes data deemed less important to human vision to reduce file size.

Q3. What's the best JPEG quality setting?

• Web use: 60-80%
• Print: 80-100%
• Largest file size
• Archive: 100%

Q4. Can JPEG files be transparent?

No, JPEG format does not support transparency. Use PNG file format or WebP formats for images that require transparency.

JPG file can be opened by default image programs of operating systems. Mostly all image viewer has compatibility to open and view JPG files.

• Windows - Photos app, Paint, Windows Photo Viewer, File Explorer preview
• Mac - Preview, Photos, Quick Look, Safari
• Mobile - Native gallery apps, Photo editing apps, File managers