ECW (Enhanced Compressed Wavelet File, .ecw)

ECW (Enhanced Compression Wavelet) is an open standard wavelet compression image format developed by Earth Resource Mapping. The file format is optimized for aerial and satellite imagery, and efficiently compresses very large images with fine, alternating contrast. This is a lossy compression format.

It has the following properties:

• embeds map projection information
• fast compression (about 1.5 MB of compressed file per second on 1 GHz processor)
• typical compression ratios between 1:10 and 1:100
• possible decompression of selected regions without the need to decompress the whole file
• data flow compression allows for compression of big files with small RAM requirements

Despite being open standard, there does not currently unfortunately seem to be any Free Software to read or write ECW. However MapWindow GIS is a Free Software GIS application that can easily read ECW files and use them in their projects.