Shape information coder and decoder dividing shape information into lower-resolution subsets
AssigneeOki Electric Industry Co., Ltd.
InventorYoshihiro Ueda
Life of this patent
Estimating the term…
Abstract
A shape information coder divides the pixels in the shape information into subsets representing different subsamplings of the shape information. Each pixel in each subset is coded with reference to a context which may be derived from reference pixels in more than one of the subsets. The context preferably includes reference pixels located on all sides of the pixel being coded, which leads to efficient coding. The shape information coder may have two or more cascaded stages, each operating as above, with one subset of pixels passed from each stage to be coded in the next stage. The resulting coded shape information is useful in, for example, wavelet coding of pictures.
Claims11
A shape information decoder for decoding coded shape information relating to a particular image, the coded shape information including a plurality of mutually exclusive coded subsets of shape information, each coded subset of shape information having lower resolution than the coded shape information as a whole, the shape information decoder comprising:
- decoding means decoding said coded shape information according to context information, thereby generating a plurality of subsets of pixels, said subsets including at least a plurality of first-resolution subsets and a plurality of second-resolution subsets, the first-resolution subsets having a first resolution, the second-resolution subsets having a second resolution, the second resolution being higher than the first resolution;
- first memory means coupled to said decoding means, storing said first-resolution subsets of pixels;
- first context generating means coupled to said first memory means, selecting, for each pixel in one of said first-resolution subsets, reference pixels already decoded by said decoding means, and generating said context information from the selected reference pixels;
- first resolution deconverting means reassembling said first-resolution subsets of pixels to generate second-resolution shape information having said second resolution;
- second memory means coupled to said decoding means, storing said second-resolution shape information and said second-resolution subsets of pixels;
- context generating means coupled to said second memory means, selecting, for each pixel in one of said second-resolution subsets, reference pixels already decoded by said decoding means or belonging to said second-resolution shape information, and generating said context information from the selected reference pixels;
- and
- second resolution deconverting means reassembling said second-resolution subsets of pixels and said second-resolution shape information to generate third-resolution shape information having a third resolution, the third resolution being higher than the second resolution.
Dependencies are inferred from the claim text.