程序Adobe PhotoshopApple PreviewCorel Paint Shop Pro
主程序MS Paint
说明JPEG – is a popular graphic format, which is characterized by a high degree of compression, which leads to a decrease in image quality. It uses the technology of encoding of smooth color renditions, providing the ability to reduce the amount of data frequently during the recording of the image.
Because of the small size it is requested by the owners of websites, allowing you to save the traffic effectively. It is also frequently used in memory cards of digital video cameras. The JPEG algorithm is optimally suitable for compressing photographs and pictures, in which realistic scenes with little contrast of colors are present. It is not recommended to use this format for compression of drawings and various kinds of graphics, since a strong contrast between a number of closely located pixels provokes the appearance of visible artifacts.
技术细节The procedure for compressing the digital images in JPEG format is carried out in several stages. First, the photo is transformed into a color space YCbCr, then it is divided into squares to determine the upper range of the color spectrum. Finally, the colors and brightness are coded.
JPEG uses a "lossy" compression system and discrete cosine transform technology. The format acts simultaneously as the standard of ISO and the International Telecommunication Union. The file compression ratio is in the range from 10:1 to 100:1. In this case, the reduction in image quality can vary from insignificant to substantial.
