Formats PNG-8 and PNG-24

Both formats PNG can save translucent areas (for example, the softened shaded boundaries), using a method under a title an alpha transparency. In this case the point can have 256 levels of opacity, since the full transparency and finishing the full opacity. In format PNG-8 the greatest possible amount of colors of the optimized image - 256, this format is similar on GIF. In format PNG-24 the image can have millions colors, this format, in turn, is similar on JPEG. In formats PNG the compression method lost-free the data is used.

What restrictions at usage of formats PNG exist? For example, in this format it is impossible to create animation (and in format GIF it is possible), except that, files in format PNG-24 it is more on the size of similar JPEG-files. And that it is even more important, formats PNG immediately it is not supported by two main web browsers, except for versions Internet Explorer 4.0 and Netscape Navigator 6 and later. In the given format the embeddable unit, for example PNG Live is required to prior versions of these programs for display of pictures. Than these units are bad? The user, probably, does not want to waste time on loading of the embeddable unit, and without it your site will not look as advantageously, as at its usage.