What is JEPG?

What is JEPG?

JPEG Joint Photographic Experts Group is a standard for continuous tone static image compression. The file suffix is ​​jpg or jpeg. It is the most commonly used image file format. It mainly uses predictive coding. , discrete cosine transform and joint coding method of entropy coding.

JPEG Performance

JPEG performance, measured by the ratio of quality to bitrate, is quite superior. Its advantages are:

• It supports extremely high compression rates, so the download speed of JPEG images is greatly accelerated.

• It can easily handle 16.8M colors and can reproduce full-color images well.

• During the image compression process, this image format allows you to freely choose between the smallest file size (lowest image quality) and the largest file size (highest image quality).

• The file size of this format is relatively small and the download speed is fast, which is conducive to transmission when the bandwidth is not "rich".

The disadvantages of JPEG are:

• Not all browsers support inserting various JPEG images into web pages.

• When compressing, the quality of the image may be lost, so it is not suitable to use this format to display high-definition images.

JPEG's low complexity and long use time are impressive. The following are the several levels given by JPEG as criteria for measuring the compression encoding effect for images of moderately complex images at 8 bits/pixel:

• 0.25 bits/pixel~0.5 bits/ Pixels; Medium~Good, enough for some applications.

• 0.5 bits/pixel ~ 0.75 bits/pixel; good ~ very good, enough for many applications.

• 0.75 bits/pixel ~ 1.5 bits/pixel; excellent, enough for most applications.

• 1.5 bits/pixel ~ 2.0 bits/pixel; difficult to distinguish from the original image, sufficient to meet most applications.

• >2.0 bits/pixel; almost perfect, meeting almost all applications.

The bit/pixel (bit/pixel) is defined as the total number of bits in the compressed image (including the chroma component) divided by the number of samples of the luminance component.

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