Method of removing block boundary noise components in block-coded images
First Claim
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1. A method for restoring a block-encoded image, comprising:
- estimating block boundary noise components residing across two neighboring blocks in the block-encoded image, wherein the block boundary noise components comprise block boundary discontinuity parameters, which are estimated by subtracting the sum of the average of internal pixel slopes divided by two from a boundary pixel slope;
decoding the block-encoded image to obtain a decoded image; and
eliminating the estimated block boundary noise components from the decoded image.
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Abstract
An improved block noise elimination method is provided, which uses one-dimensional pixel vectors made of pixel rows or columns across two neighboring blocks to analyze blocky noise residing across the neighboring blocks. The blocky noise in each pixel-vector is modeled as shape vector multiplied by boundary discontinuity. The shape vector, varying with local image activity, is estimated by Minimum Mean Squared Error (MMSE) approach. Depending upon the shape vector, the corresponding blocky noise is eliminated in postprocessing of decoded images so that encoded images may be restored to their original images.
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Citations
19 Claims
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1. A method for restoring a block-encoded image, comprising:
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estimating block boundary noise components residing across two neighboring blocks in the block-encoded image, wherein the block boundary noise components comprise block boundary discontinuity parameters, which are estimated by subtracting the sum of the average of internal pixel slopes divided by two from a boundary pixel slope;
decoding the block-encoded image to obtain a decoded image; and
eliminating the estimated block boundary noise components from the decoded image. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
calculating the block boundary discontinuity parameters and the local image activity parameters of the encoded pixel vectors;
obtaining shape vectors corresponding to the respective local image activity parameters; and
removing products of the block boundary discontinuity parameters and the shape vectors from decoded pixel vectors, respectively.
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12. The method of claim 1, further comprising transferring the estimated block boundary noise components to a decoding part prior to said eliminating the estimated block boundary noise components.
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13. The method of claim 12, wherein said estimated block boundary noise components are transferred to the decoding part together with encoded pixel vectors in real time.
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14. The method of claim 12, wherein said estimated block boundary noise components are previously stored in a table within the decoding part.
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15. A method for restoring encoded images, comprising:
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sequentially receiving encoded pixel vectors of the encoded images;
calculating local image activities of the encoded pixel vectors, each local image activity corresponding to each encoded pixel vector;
estimating shape vectors representing block boundary noises of the encoded images, the shape vectors varying with the local image activities and each shape vector corresponding to each encoded pixel vector;
sequentially receiving decoded pixel vectors of decoded images;
calculating local image activities of the decoded pixel vectors, each local image activity corresponding to each decoded pixel vector;
obtaining the shape vectors estimated in the step of estimating, each obtained shape vector corresponding to each local image activity; and
removing each of the shape vectors obtained in the step of obtaining from corresponding one of the decoded pixel vectors. - View Dependent Claims (16, 17, 18, 19)
calculating block boundary discontinuities of the respective encoded pixel vectors;
obtaining boundary noise components of the respective encoded pixel vectors, each boundary noise component being obtained by dividing a difference between each encoded pixel vector and a corresponding original pixel vector by the corresponding block boundary discontinuity; and
adding each of the boundary noise components to a previously estimated shape vector.
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17. The method of claim 15, wherein the step of removing the shape vectors includes the steps of:
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calculating block boundary discontinuities of the respective decoded pixel vectors;
obtaining products of the respective block boundary discontinuities of the respective decoded pixel vectors and the respective shape vectors obtained in the step of obtaining; and
subtracting each of the products from corresponding one of the decoded pixel vectors.
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18. The method of claim 15, wherein one of the local image activities corresponding to one of the pixel vectors is determined by a largest one of nonzero coefficient indices of the corresponding pixel vector.
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19. The method of claim 15, wherein the step of obtaining the shape vectors includes retrieving corresponding shape vectors which are previously stored in a table of a decoding part.
Specification