PNG format: a free GIF, but better

The PNG format is a format for lossless raster images, which is able to replace such classic formats as TIFF and GIF. It was designed to work mainly with WWW applications; it is robust and provides integrity checks for the file.

It was designed for the purpose of replacing the GIF format, but it also has additional design properties that were added with small effort from the designers. The features that are implemented in PNG and are absent in GIF format include:

1.  Support for images with up to 48 bits per pixel, in True Color. (comparing to 256 colors implemented in the GIF format)
2. Support for grayscale images of up to 16 bits per pixel
3. The addition of full Alpha channel (full transparency masks)
4. Additional image gamma information (it keeps it’s brightness, contrast and other information, so that it could be portable between different machines)
5. Straightforward and easy detection of file corruption.

The development of the PNG standard, together with the development of the specification was supported by the W3C consortium, together with CompuServe Inc, and the main development job was executed by the PNG Development Group.

It was kept in mind that the PNG format should be easily implemented by other developers, so the format is concise and simple. Another strong point of the PNG format is the fact that it is 100% open and doesn’t contain any proprietary code, so that it could be used without attracting excessive attention to the legal problems. Also, by using an algorithm that allows the addition of extensions, it allows for permanent evolution of the format.

The main problem about the PNG format until recent times was browser support. It was supported in Mozilla and Opera browsers, but lacked the required support in Internet Explorer. But after apparition of Internet Explorer 8, it has full support with all the modern browsers.