Abstract
A lightweight and efficient image compression method which is implemented by only using several line-memories as the memory unit, was studied. A hybrid encoding method is adopted, in which one-dimensional Slant transform is used to the horizontal scanning and DPCM coding to encode the transformed coefficients is used to the vertical scanning. The Slant transform has the feature that the number of multiplication is significantly reduced with a little deterioration of image quality, compared with DCT. In this study, the Slant transform was modified to have the character like Wavelet transform, that is, it takes only high frequency coefficients at lower small blocks and takes only low frequency coefficients at the highest large block. The amount of the computation for the transform was further reduced by calculating only the low frequency coefficients at higher large blocks. The simulation evaluation of this method showed that a favorable compression performance is obtained.
