IMAGE CODING/DECODING METHOD, IMAGE CODING APPARATUS AND IMAGE DECODING APPARATUS
First Claim
1. An image coding/decoding method in which an image coding apparatus sends coded information which is obtained by coding an original image to an image decoding apparatus and said image decoding apparatus decodes said coded information to obtain a reproduced image, said method comprising the steps of:
- extracting edge information which is binary information representing an edge part of said original image;
obtaining density information of an edge unsharpened image from said original image by unsharpening said edge part using said edge information;
obtaining coded edge information by coding said edge information according to a first coding algorithm;
obtaining coded density information by coding said density information of said edge unsharpened image according to a second coding algorithm;
sending said coded edge information and said coded density information as said coded information to said image decoding apparatus; and
said image decoding apparatus performing the steps of;
obtaining said edge information by decoding said coded edge information according to a first decoding algorithm corresponding to said first coding algorithm;
obtaining said density information of said edge unsharpened image by decoding said coded density information according to a second decoding algorithm corresponding to said second coding algorithm;
obtaining said reproduced image from said density information of said edge unsharpened image by restoring said edge part of said edge unsharpened image by using said edge information;
wherein said second coding algorithm and said second decoding algorithm are based on a standard coding method using a discrete cosine transform.
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Abstract
An image coding method is provided, in which the method includes the steps of: extracting edge information which represents an edge part of an original image; obtaining density information of an edge smoothed image from the original image by smoothing the edge part; obtaining coded edge information by coding the edge information according to a first coding algorithm; obtaining coded density information by coding the density information of the edge smoothed image according to a second coding algorithm; and sending the coded edge information and the coded density information as coded information to an image decoding apparatus.
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Citations
15 Claims
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1. An image coding/decoding method in which an image coding apparatus sends coded information which is obtained by coding an original image to an image decoding apparatus and said image decoding apparatus decodes said coded information to obtain a reproduced image, said method comprising the steps of:
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extracting edge information which is binary information representing an edge part of said original image; obtaining density information of an edge unsharpened image from said original image by unsharpening said edge part using said edge information; obtaining coded edge information by coding said edge information according to a first coding algorithm; obtaining coded density information by coding said density information of said edge unsharpened image according to a second coding algorithm; sending said coded edge information and said coded density information as said coded information to said image decoding apparatus; and said image decoding apparatus performing the steps of; obtaining said edge information by decoding said coded edge information according to a first decoding algorithm corresponding to said first coding algorithm; obtaining said density information of said edge unsharpened image by decoding said coded density information according to a second decoding algorithm corresponding to said second coding algorithm; obtaining said reproduced image from said density information of said edge unsharpened image by restoring said edge part of said edge unsharpened image by using said edge information; wherein said second coding algorithm and said second decoding algorithm are based on a standard coding method using a discrete cosine transform. - View Dependent Claims (2, 3, 4)
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5. An image coding apparatus comprising:
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an edge extracting part for extracting edge information which is binary information representing an edge part of an original image; an edge unsharpening part for obtaining density information of an edge unsharpened image from said original image by unsharpening said edge part using said edge information; a first coding part for obtaining coded edge information by coding said edge information according to a first coding algorithm; a second coding part for obtaining coded density information by coding said density information of said edge unsharpened image according to a second coding algorithm; wherein said coded edge information and said coded density information are coded information of said original image, and wherein said second coding algorithm is based on a standard coding method using a discrete cosine transform. - View Dependent Claims (6, 7, 8, 9)
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10. An image decoding apparatus which decodes coded information which includes coded edge information obtained by coding edge information representing an edge part of an original image and coded density information representing an edge unsharpened image obtained by unsharpening said edge part of said original image using said edge information, said image decoding apparatus comprising:
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a first decoding part for obtaining said edge information which is binary information representing said edge part by decoding said coded edge information according to a first decoding algorithm; a second decoding part for obtaining density information of said edge unsharpened image by decoding said coded density information according to a second decoding algorithm; an edge restoring part for restoring said edge part of said edge unsharpened image by using said edge information such that a reproduced image is obtained, wherein said second decoding algorithm is based on a standard coding method using a discrete cosine transform. - View Dependent Claims (11, 12, 13, 14, 15)
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Specification