What is JPEG (Joint Photographic Experts Group)?

JPEG is one of the most popular formats for saving digital images. The Joint Photographic Experts Group created this file type, which is abbreviated JPEG or JPG.

JPEG (Joint Photographic Experts Group) Definition

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 photos. 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 picture type used by digital cameras and other photo 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, and usability arose, graphic designers thought that the larger the photo, the better the resolution and print of the image.

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

This format plays a vital 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 photo representing a larger size.

JPEG Format File Features

The compression system used in the JPEG format 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, JPEG 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 into this standard.

The features of this graphic format are quite different from the GIF extension. So, these two standards are used in HTML because one tries to complement the other.

The features of the JPEG or JPG are:

  1. It has a bitmap graphic standard.
  2. It supports 24-bit actual color.
  3. It has a compression algorithm that supports high packet rates.

JPEG format 24-bit genuine color support provides images with a color depth of 16,777,216. A bitmap with this color depth would reach huge memory sizes. However, this is supported by the compaction algorithm offered by the standard.

Although this compression algorithm is mighty, if its ratio increases, we will see a slight decrease in image quality.

For example, when we save the file from our image processor, it adjusts the ratio. This loss of information occurs when we increase its rate. However, we visibly notice the resolution of the image.

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

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 photo, we cannot get the exact image we had before compressing it. One of the features that make JPEG standard 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 ratio, a quality that is 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 quality. However, the more times you recompress the photo, the greater the loss. So, every time you compress and decompress it, it will lose some quality.

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

This compression algorithm is based on two visual defects of the human eye. The first flaw is that the picture 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 significant.

P-JPEG (Progressive)

The main advantage of the P-JPEG layout is that it allows images to be displayed progressively. P-JPEG is based on showing images 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 photo processing is complete.

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