What is the format of png?

PNG format

PNG is an image file storage format developed in the mid-1990s. Its purpose is to replace GIF and TIFF file formats and add some functions that GIF file formats do not have. The name of Portable Network Graphics Format (PNG) comes from the unofficial "PNG's Not GIF", which is a bitmap file storage format pronounced "ping". When storing grayscale images with PNG, the depth of grayscale images can be as high as 16 bits, when storing color images, the depth of color images can be as high as 48 bits, and α channel data can also be stored as high as 16 bits. PNG uses lossless data compression algorithm derived from LZ77.

The PNG file format retains the following characteristics of the GIF file format:

You can support 256-color images by using a color look-up table or a color palette.

Fluency reading/writing performance: The image file format allows continuous reading and writing of image data, which is very suitable for generating and displaying images during communication.

Progressive display: this function can display the image on the terminal while transmitting the image file on the communication link, and gradually display the details of the image after displaying the overall outline of the image, that is, display the low-resolution image first, and then gradually improve its resolution.

Transparency: This ability can make some parts of the image not displayed, and it can be used to create some unique images.

Auxiliary information: This function can be used to store some text annotation information in an image file.

Independent of computer software and hardware environment.

Use lossless compression.

In the PNG file format, you should add the following functions that are not available in the GIF file format:

Each pixel is a 48-bit true color image.

Each pixel is a 16-bit grayscale image.

You can add alpha channels for grayscale and true color maps.

Add the gamma information of the image.

Use cyclic redundancy code (CRC) to detect corrupted files.

Speed up the successive approximation display mode of image display.

Standard read/write toolkit.