Image encoding and decoding method and apparatus using edge synthesis and inverse wavelet transform
AssigneeOki Electric Industry Co., Ltd.
InventorShiyu Go
Life of this patent
Estimating the term…
Abstract
A digitized image is encoded by detecting edges in the image, encoding the position and sharpness of the detected edges, filtering the image by a low-pass filter to generate a low-frequency image, and encoding the low-frequency image. A digitized image encoded in this way is reconstructed by generating a horizontal edge image and a vertical edge image from the encoded edge position and sharpness information, synthesizing a pair of high-frequency images by filtering the horizontal and vertical edge images with an edge synthesis filter, decoding the low-frequency image, and performing an inverse wavelet transform on the decoded low-frequency image and the high-frequency images.
Claims28
A system for encoding and decoding a digitized image consisting of pixels having pixel values, comprising:
- an input terminal for receiving said digitized image;
- a series of smoothing filters coupled to said input terminal, having progressively lower cut-off frequencies, for filtering said digitized image to generate a series of filtered images culminating in a low-frequency image, which was filtered with a lowest cut-off frequency among said cut-off frequencies;
- a down sampler coupled to a last one of said smoothing filters in said series, for down-sampling said low-frequency image to generate a reduced image;
- means for generating an edge image by detecting edge points in one image among said digitized image and said filtered images, excluding said low-frequency image;
- an encoding section coupled to said means for generating an edge image and said down sampler, for encoding said edge image, thereby obtaining edge information, and encoding said reduced image, thereby obtaining low-frequency information;
- a decoding section for decoding said edge information to generate a pair of edge images, comprising a horizontal edge image and a vertical edge image, and decoding said low-frequency information to regenerate said reduced image;
- an up sampler, coupled to said decoding section, for up-sampling said reduced image to generate a decoded low-frequency image equal in size to said edge images;
- a plurality of edge synthesizers, each coupled to said edge information decoder having respective edge synthesis filters, for synthesizing a series of pairs of high-frequency images by filtering said horizontal edge image horizontally and said vertical edge image vertically with said edge synthesis filters;
- an inverse wavelet transform processor, coupled to said up sampler and said plurality of edge synthesizers, for performing an inverse wavelet transform on said decoded low-frequency image and said series of pairs of high-frequency images;
- and
- means for transmitting said edge information and said low-frequency information from said encoding section to said decoding section.
Dependencies are inferred from the claim text.