What Is JPEG?

Date First Published: 28th July 2023

Topic: Computer Systems

Subtopic: Computer Software

Article Type: Computer Terms & Definitions

Difficulty Level: 5/10

Learn about what JPEG is in this article.

Stands for Joint Photographic Experts Group. JPEG is an image format that has a 24-bit colour depth, the same as BMP images, and uses lossy compression to reduce the number of colours being used, reducing the file size. This means that some image quality is lost during the compression process and the image cannot be decompressed to its original state once saved as a JPEG. However, the level of compression can be set to get the most suitable quality to file size ratio.

The JPEG file format is often used for storing photographs, particularly when sharing them over the internet, by email, social media, or cloud storage since it offers high-quality whilst reducing the file size. Unlike PNG files, JPEG files can also contain metadata that describes the contents of the file, including the dimensions, colour space, colour profile information, and EXIF data, which is often stamped on the image by a digital camera.

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JPEG files have the ".jpeg" file extension and the "image/jpeg" MIME media type.

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The acronym JPEG is pronounced as two words: "jay-peg".

Difference Between JPEG, JPG, and PNG

JPEG and PNG are the two most widely used image formats on the web, but there are some differences between them. The main difference between a PNG and JPEG file is the loss of quality. Since PNG uses lossless compression, saving it does not reduce its quality or cause it to lose any original file data when compressed.

Due to the different compression processes, JPEG files contain less data than PNG files, take up less space, and load faster on the web than PNGs. Unlike PNGs, JPEGs do not support transparent backgrounds, making them less suitable for graphic design, logos, and pictures with text. Since the sharp contrasts between different pixels can cause noticeable artifacts, JPEG is not well suited for line drawings and other textual or iconic graphics.

There is no difference between the JPEG and JPG formats. Both JPEG and JPG are equivalent file formats and the only difference is the number of characters used. Both can be used based on personal preference. The JPG file format only exists because earlier versions of Windows operating systems, such as Microsoft DOS, Windows 3.x, Windows 95, Windows 98, and Windows NT do not support file extensions longer than three characters. The file extension '.jpeg' is more common as most servers and operating systems support four-letter file extensions.

JPEG File Size

The size of a JPEG file varies, depending on the dimensions of the image and the resolution. The higher the resolution and the larger the length and width of the image, the larger the image size. Some JPEG files can be tens or even hundreds of MB in size due to the increased quality of image editing software and digital cameras. However, it is best to only use the necessary resolution for your needs and not use a resolution larger than needed to avoid wasting storage space and increasing the loading time of webpages.

History

The JPEG format is named after the Joint Photographic Experts Group. The organisation developed the JPEG standard in the late 1980s and released the first JPEG specification in 1992. Since then, the organisation has developed several versions of the format, including JPEG 2000 and JPEG XR, but the standard JPEG format remains the most widely used.

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