Could anyone please explain briefly the difference between JPEG and EZW? And why JPEG is more popular? Is JPEG always better than EZW or just in most of the cases?
Thank you very much!
EZW is a theoretical technique which can be used as one step in wavelet compression. It's not a complete image encoder, and can't be used on its own. As best I can tell, nobody has proposed any image formats which depend on EZW, so nothing uses it (to the best of my knowledge).
(As an aside, wavelet image compression techniques have generally proven unsuccessful.)
JPEG, by contrast, is a standard which encompasses all layers of an image compressor, including the DCT as well as everything surrounding it: color space, entropy coding, file format, metadata, etc. Unlike EZW, it's been a complete, usable standard since 1992.