On the use of (lapped) multiple transforms in still image compression

We describe a system for still image compression which uses several lapped orthogonal transform (LOT) sets in a multiple bases realization (MBR) algorithm, the recursive residual projection (RRP) algorithm. Newly developed RRP algorithms are shown to reduce the number of encoded transform coefficients 20% beyond the discrete cosine transform (DCT)-only compression standard, JPEG. These algorithms still suffer from the problem of block-discontinuities at the boundaries of the segmented image. We extend these algorithms to use several newly developed LOT bases, which result in useful algorithms for low bit-rate (high compression) operation. We see that our proposed methods have superior % MSE for equal numbers of coefficients when compared to several transform coding methods.