What is JPEG (Joint Photographic Experts Group)?

JPEG is one of the most popular formats for saving digital images. This file type was created by the Joint Photographic Experts Group and is abbreviated JPEG or JPG.

What is JPEG (Joint Photographic Experts Group)?

What is JPEG Format/File?

JPEG is the name of an expert committee that establishes a standard for the compression and encoding of still image files.

This committee was formed by the unification of various groups in order to share and develop their experiences in digitizing images. ISO started research in this area three years ago.

Apart from being a compression method, JPEG is generally considered a file format.

JPEG is the most common image type used by digital cameras and other image capture devices, as well as for storing and transmitting photographic images on the World Wide Web. Such files are usually named with the .jpg extension.


Before the need for web design, development, programming, usability arose, graphic designers thought that the larger the size of the image, the better the resolution and print of the image.

Later, there was a need to switch from printed design on the web to normal design. Massive images printed in full color on the web had to be compressed and reduced in size to be easily uploaded.

This format plays an important role as it allows us to rank the compression level of each of the images.

This can create a low-quality image, which means a smaller size in the file, or a high-quality image representing a larger size.


The compression system used by JPEG is based on the method of reducing information by averaging it in gradient fields. That is, the color value of some pixels is calculated based on the color of the pixels surrounding them.

Due to these properties, this format is very effective when storing images with many gradients and color differences.

We should know that there will be no difference in image size when we want to convert drawings with wide extensions in plain and uniform colors and drawings with very well defined edges in this format into this format.

The features of this graphic format are quite different from the GIF extension. So these 2 formats are used by the HTML language because one tries to complement the other.

The features of the JPEG or JPG are:

  1. It has a bitmap graphic format.
  2. It supports 24-bit true color.
  3. It has a compression algorithm that supports high packet rates and more.

JPEG’s 24-bit true-color support delivers images at 16,777,216 color depths. A bitmap with this color depth can reach very large memory sizes. However, this is supported by the compression algorithm the format offers.

Although this compression algorithm is very powerful, it can cause a slight decrease in image quality as the compression rate increases.

For example, when we save the file from our image processor, the compression rate is adjusted. This loss of information occurs when we increase the compression ratio and the resolution of the image is visibly noticeable.

This format is an algorithm designed to compress images with a depth of 24 bits and in grayscale. It is also the file format this algorithm uses to store compressed images.

It only processes still images, but there is a standard for videos called MPEG.

This file format is often abbreviated as .jpg because some operating systems only accept three-letter extensions. In short, this image extension is a lossy compression algorithm.

This means that when decompressing the image, we cannot get the exact image we had before compressing it. One of the features that make this file format very flexible is the ability to adjust the degree of compression.

If too high compression is specified, it will result in a significant loss of quality, but small files will be obtained. With a low compression ratio, a quality very close to the original and a larger file can be obtained.

It means that if you compress and decompress an image only once, you’ll get image quality. However, the more times you recompress the image, the greater the loss. So every time you compress and decompress the image, it will lose some quality.

Although this format is the most widely used file format on the web, the format is not suitable for lossy compression, text, and diagrams containing lines.

This compression algorithm is based on two visual defects of the human eye. The first flaw is that the image compressed in a bright environment is more clearly noticeable. The second is that small changes in non-homogeneous areas, for example at the edges of bodies of objects, are more easily noticed than areas where the variation is large.

P-JPEG (Progressive)

The main advantage of the P-JPEG format is that it allows images to be displayed progressively. P-JPEG is based on displaying the image from low to high quality while loading graphics.

We should not confuse it with the raster system of the GIF format, as the GIF is based on showing the changing lines of the graphic during loading.

The progressive imaging system of P-JPEG reaches maximum sharpness when the image processing is complete.

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