PNG
PNG
(Portable Network Graphics) is a file format for compressed graphic images
that is expected to replace the GIF format. PNG was developed by an Internet
committee and will be patent-free. PNG
provides a number of improvements over the GIF format. Like a GIF, a PNG
file is compressed lossless. A PNG file is not intended to replace the
JPEG format, which is "lossy" but lets the user make a choice between
compression and quality when the image is restored. Ideally, an image
in a PNG file can be 10 to 30% more compressed than in a GIF format.
The PNG format includes the following features: - transparency of colour, plus a control of the degree of transparency (opacity).
- Interlacing.
- Gamma correction allows you to "tune" the image in terms of colour brightness for specific platforms (for example, one tuning for Windows and another for the Mac).
- Images can be saved using truecolour as well as in the palette and gray-scale formats provided by the GIF.
At this moment some features e.g. the transparency do
not yet function in the browser versions now available. Many of above
mentioned features however will be implemented in the near future. PNG
file doesn't support animation.
Software houses will be able to develop variations of PNG that can contain
multiple, scriptable images.
When to use PNG compression
This
compression method is best used for similar images as were mentioned for
GIF.
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