JPEG is the abbreviation of Joint Photographic Experts Group. The file name is ".. jpg" or ". Jpeg ",which is the most commonly used image file format. It is a lossy compression format organized by the Software Development Association. It can compress the image in a small storage space, and the repeated or unimportant data in the image will be lost, which will easily cause the damage of the image data. Especially, if the compression ratio is too high, the quality of the restored image after final decompression will obviously decrease. If you pursue high-quality images, you should not use too high compression ratio. But JPEG compression technology is very advanced. It uses lossy compression to remove redundant image data, and can display very rich and vivid images at the same time, in other words, it can obtain better image quality with the least disk space. Moreover, JPEG is a very flexible format, which has the function of adjusting image quality, allowing files to be compressed at different compression ratios and supporting multiple compression levels. The compression ratio is usually between 10: 1 and 40: 1. The higher the compression ratio, the lower the quality. On the contrary, the smaller the compression ratio, the better the quality. For example, a BMP bitmap file of 1.37Mb can be compressed to 20.3KB Of course, you can also find a balance between image quality and file size. JPEG format mainly compresses high-frequency information and preserves color information well. It is suitable for the Internet, can reduce the image transmission time, can support 24-bit true color, and is also widely used in images that need continuous tone.
JPEG format is the most popular image format on the network at present, which can compress files to a minimum. When stored in JPEG format in Photoshop software, the compression level of 1 1 is provided, which is represented by 0- 10. Level 0 has the highest compression ratio and the worst image quality. The compression ratio can reach 5: 1 even if the quality maintenance with almost no loss of details is adopted. When saving in BMP format, you will get a 4.28MB image file. When saved in JPG format, the file size is only 178KB, and the compression ratio reaches 24: 1. After many comparisons, eight-level compression is the best ratio of storage space and image quality.
JPEG format is widely used, especially on the Internet and CD-ROM. At present, all kinds of browsers support JPEG as the image format, because the file size of JPEG format is small and the download speed is fast.