Encoding method and apparatus for representing a digital image

摘要

The method encodes a digital image to provide a compressed representation of the image. The method initially performs a multi-level 2-D Discrete Wavelet Transform on the digital image, which is arranged in a hierarchical order of sub-bands. The method then tiles each sub-band to form a number of blocks of transform coefficients. The method then encodes each bitplane of each block from a maximum bitplane to a minimum bitplane in the following manner. The method divides a current bitplane into a number of first areas and/or a number of second areas, wherein each first area comprises a number of coefficients having corresponding most significant bits in the current bitplane or less and each second area comprises a number of coefficients having corresponding most significant bits in a bitplane greater than the current bitplane. The method then codes the significance of each first area in the current bitplane; and codes a corresponding bit of each coefficient in each second area of the current bitplane.