.PNG 文件扩展名

PNG is one of the most common image formats, along with JPEG, GIF, TIFF, and EPS. Examples of when you might encounter a PNG file include:

• Downloading an image from the Internet or an image attached to an email
• Saving a digital photograph with an image editor, such as a logo or icon designed by a graphics professional or web designer
• Taking a screenshot in Windows or macOS 10.4 and later (Ubuntu Linux also stores print screen screenshots in the PNG format)

Why the PNG format was created

PNG was created in 1995 to be a free alternative to the GIF format for transferring images on the web. It improved upon the limitations of the GIF format, which supported a limited number of colors and included a patent license. Additionally, while GIF images only support fully opaque or fully transparent pixels, PNG images may include an 8-bit transparency channel, which allows the image colors to fade from opaque to transparent.

Other PNG features include support for indexed (palette-based) 24-bit RGB or 32-bit RGBA (RGB with a fourth alpha channel) color images. The format also supports full-color, non-indexed RGB or RGBA images and grayscale images.

While the PNG format became more widely used than GIF, PNG is a single-image format, whereas GIF supports multiple images. The GIF format allowed users to save simple animations as GIF files and led to the format's resurgence online, especially on social media. In response to this limitation, the PNG Development Group created the Multiple-image Network Graphics (.MNG) format in 2001, but it was not widely adopted like the GIF format.