Compression of multispectral images by three-dimensional SPIHT algorithm

We carry out low bit-rate compression of multispectral images by means of the Said and Pearlman’s SPIHT algorithm, suitably modified to take into account the interband dependencies. Two techniques are proposed: in the first, a three-dimensional (3-D) transform is taken (wavelet in the spatial domain, Karhunen–Loeve in the spectral domain) and a simple 3-D SPIHT is used; in the second, after taking a spatial wavelet transform, spectral vectors of pixels are vector quantized and a gain-driven SPIHT is used. Numerous experiments on two sample multispectral images show very good performance for both algorithms.