The Animated Portable Network Graphics (APNG) is an unofficial extension to the Portable Network Graphics (PNG) file format that supports animation.
APNG is a new technology which is still not adopted by most browsers; Firefox 3 and Opera 9.5 are the only browsers that support APNG.
The two most apparent problems are that GIF images can only contain 256 colors, and lack support for partially-transparent pixels.
This results in images which often look grainy or rough, and which do not smoothly blend into their background.
Let’s take the following example:
Both show the same GIF animation.