PNG adopts lossless data compression algorithm derived from LZ77. Because of its high compression ratio and small file size, PNG is generally used in JAVA programs, web pages or S60 programs.
Small size? Due to the limitation of network communication bandwidth, bmp files with large files cannot be widely used in web pages on the premise of ensuring clear and realistic pictures.
Lossless compression? PNG files are compressed by the derivative algorithm of LZ77 algorithm, and the result is high compression ratio without losing data. It uses a special coding method to mark the repeated data, so it has no influence on the color of the image, and it is impossible to fade, so it can be saved repeatedly without reducing the image quality.
Indexed color model? PNG-8 format is similar to GIF image, and also uses 8-bit palette to convert RGB color images into index color images. What is stored in the image is not the color information of each pixel, but the representative color numbers selected from the image, and each number corresponds to a color, so that the data amount of the image is reduced, which is very beneficial to the spread of color images.
More optimized network transmission display? PNG images are streamed on the browser, even though interlaced images will provide viewers with a basic image content before they are completely downloaded, and then gradually become clear. It allows continuous reading and writing of image data, which is very suitable for displaying and generating images during communication.
Support transparent effect? PNG can define 256 transparent layers for the original image, so that the edge of the color image can be smoothly blended with any background, thus completely eliminating jagged edge. This feature is not available in GIF and JPEG.
PNG also supports Alpha channel transparency for true color and grayscale images. Supports up to 24-bit true color images and 8-bit grayscale images. Transparent/translucent supporting Alpha channel. Gamma calibration information supporting image brightness. Support the storage of additional text information, so as to retain information such as picture name, author, copyright, creation time, comments, etc.