Compression example

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The example is a satellite image of hurricane Gilbert,
which is 512-pixel wide and 512-pixel tall with 256 shades of gray. The raw image information takes 262,144 bytes.

This is the original image in GIF format

[ gilbert.gif image]

Note GIF provides some lossless compression, therefore the size of the image file is 179,870 bytes

The following image has been compressed using a SOWLP method. The compression is lossy, so you will see some degradation. But the image data file is only 14,032-byte long!

Click here to view the image

The image is decompressed as you retrieve it

Note that only less than 14K is sent from a server to your local station. The decompression is done locally on your computer. You may want to compare the time it took to retrieve the gif and slpg images


Interactive Image compression

Now you can compress and decompress the image as you wish.

[It is no longer available]

You need to specify the value of a quality parameter, which determines the amount of compression and image degradation

Generally speaking, it is impossible to represent this relation in a concise mathematical form. Besides, it depends on the image.
However, for the satellite image above, quality parameter 90 gives 19:1 compression, quality parameter 1100 corresponds to a 64:1 compression. You can see it for yourself: specify the value of the parameter in the field below, and press the button to start the compression:

Quality parameter