PNG, which can be pronounced “ping” or “P-N-G,” is a compressed raster graphic format. It is commonly used on the Web and is also a popular choice for application graphics.
The PNG format was introduced in 1994, after the GIF and JPEG formats had already been around for several years. Therefore, PNG includes many of the benefits of both formats. For example, PNG images use lossless compression like GIF files, so they do not have any blurring or other artifacts that may appear in JPEG images. The PNG format also supports 24-bit color like the JPEG format, so a PNG image may include over 16 million colors. This is a significant difference between GIF and PNG, since GIF images can include a maximum of 256 colors.
Unlike the JPEG and GIF formats, the PNG format supports an alpha channel, or the “RGBA” color space. The alpha channel is added to the three standard color channels (red, green, and blue, or RGB) and provides 256 levels of transparency. JPEG images do not support transparent pixels and GIF images only support completely transparent (not partially opaque) pixels. Therefore, the PNG format allows Web developers and icon designers to fade an image to a transparent background rather than a specific color. A PNG with an alpha channel can be placed on any color background and maintain its original appearance, even around the edges.
While the PNG image format has many benefits, it is not suitable for all purposes. For example, digital photos are still usually saved as JPEGs, since PNGs take up far more disk space. GIFs are still used for animations since PNG images cannot be animated. Additionally, GIFs are still used on many websites since browsers only recently provided full support for the PNG format. However, now that most browsers and image editing programs support PNGs, it has become a popular file format for web developers and graphic artists.