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.
Claims21
A shape information coder for coding shape information represented by a set of pixels, comprising:
- resolution converting means dividing said set of pixels into a plurality of mutually exclusive subsets, each subset among said plurality of subsets representing a different subsampling of said shape information and having lower resolution than said shape information;
- memory means coupled to said resolution converter, storing said subsets;
- context generating means coupled to said memory means, selecting reference pixels from said memory means for each pixel in said subsets, and generating context information for each said pixel from the reference pixels selected therefor;
- and
- coding means coupled to said context generating means, coding each said subset according to the context information of the pixels in said subset.
A shape information decoder for decoding coded shape information, comprising:
- decoding means decoding said coded shape information according to context information, thereby generating a plurality of subsets of pixels;
- memory means coupled to said decoding means, storing said subsets of pixels;
- context generating means coupled to said memory means, selecting, for each pixel in said subsets, reference pixels already decoded by said decoding means, and generating said context information from the selected reference pixels;
- and
- resolution deconverting means combining said subsets of pixels to generate shape information having a higher resolution than in any one of said subsets.
A context generator generating context information for use in image processing, comprising:
- a reference pixel position and context simplification memory storing first information specifying positions of reference pixels, and second information specifying rules for converting discrete context information to simplified context information;
- a reference pixel generator coupled to said reference pixel position and context simplification memory, generating said discrete context information by obtaining values of the reference pixels in the positions specified by said first information;
- and
- a context converter coupled to said reference pixel generator, converting said discrete context information to said simplified context information according to said second information, said simplified context information having fewer states than said discrete context information.
Dependencies are inferred from the claim text.