Back to results
US 8,285,068 B2Granted
Combined deblocking and denoising filter
AssigneeCisco Technology, Inc.
InventorJoel Warren Schoenblum
Life of this patent
Estimating the term…
Abstract
An apparatus, a computer readable medium to instruct a process to implement a method, and a method of reducing blocking artifacts and/or noise in an image that has been compressed by a block-based encoding process. The method includes deblocking the image using overlapped forward directional transforms, the overlapped forward directional transforms including directional selecting to filter across horizontal and vertical boundaries, denoising the image, in one version edge detecting to classify individual pixels as to whether or not they belong to edge features, and generating output pixels by locally adapting to whether the pixels are in block boundaries, and/or include edge features.
Claims26
A method of reducing blocking artifacts in an image that has been compressed by a block-based encoding process, the method comprising:
- for a block of image data, for different horizontal and vertical shifts, including no shift in one or both directions:
- selecting a block of image data according to the shift,
- directionally forward transforming the block by a forward horizontally selecting transform to form horizontally selected transformed data and by a forward vertically selecting transform to form vertically selected transformed data, the forward horizontally selecting transform being separable to a one-dimensional horizontal forward transform followed by a directional selection operation to select significant ones of the one-dimensionally transformed values, followed by a one-dimensional vertical forward transform, the forward vertically selecting transform being separable to a one-dimensional vertical forward transform followed by a directional selection operation to select significant ones of the one-dimensionally transformed values, followed by a one-dimensional horizontal forward transform;
- and
- inverse transforming the horizontally selected transformed data and inverse transforming the vertically selected transformed data;
- forming a combination of the inverse transformed horizontally selected transformed data and the inverse transformed vertically selected transformed data for the different shifts;
- filtering the block of image data to form a block of denoised image data;
- and
- for each pixel location in the block of image data, combining the formed combination data and the denoised image data according to one or more criteria.
6 more elements
A computer readable medium having instructions coded thereon that when executed by one or more processors of a processing system carry out a method of reducing blocking artifacts in an image that has been compressed by a block-based encoding process, the method comprising:
- for a block of image data, for different horizontal and vertical shifts, including no shift in one or both directions:
- selecting a block of image data according to the shift,
- directionally forward transforming the block by a forward horizontally selecting transform to form horizontally selected transformed data and by a forward vertically selecting transform to form vertically selected transformed data, the forward horizontally selecting transform being separable to a one-dimensional horizontal forward transform followed by a directional selection operation to select significant ones of the one-dimensionally transformed values, followed by a one-dimensional vertical forward transform, the forward vertically selecting transform being separable to a one-dimensional vertical forward transform followed by a directional selection operation to select significant ones of the one-dimensionally transformed values, followed by a one-dimensional horizontal forward transform;
- and
- inverse transforming the horizontally selected transformed data and inverse transforming the vertically selected transformed data;
- forming a combination of the inverse transformed horizontally selected transformed data and the inverse transformed vertically selected transformed data for the different shifts;
- filtering the block of image data to form a block of denoised image data;
- and
- for each pixel location in the block of image data, combining the formed combination data and the denoised image data according to one or more criteria.
6 more elements
An apparatus comprising:
- a horizontal directionally selecting forward transformer operating on shifted overlapped versions of a block of image data, the horizontal directionally selecting forward transformer implementing a forward horizontally selecting transform separable to a one-dimensional horizontal forward transform followed by a directional selection operation to select significant ones of the one-dimensionally transformed values, followed by a one-dimensional vertical forward transform;
- a horizontal inverse transformer coupled to the horizontal directionally selecting forward transformer and configured to inverse transform the output of the horizontal directionally selecting forward transformer;
- a horizontal combiner coupled to the horizontal inverse transformer and configured to form a combination of the inverse transformed data for the overlapped shifts of a block for horizontal edges;
- a vertical directionally selecting forward transformer operating on shifted overlapped versions of a block of image data, the vertical directionally selecting forward transformer implementing a forward vertically selecting transform separable to a one-dimensional vertical forward transform followed by a directional selection operation to select significant ones of the one-dimensionally transformed values, followed by a one-dimensional horizontal forward transform;
- a vertical inverse transformer coupled to the vertical directionally selecting forward transformer and configured to inverse transform the output of the vertical directionally selecting forward transformer;
- a vertical combiner coupled to the vertical inverse transformer and configured to form a combination of the inverse transformed data for the overlapped shifts of a block for vertical edges;
- a denoising filter configured to contribute to denoising image data;
- and
- a local adaptation subsystem coupled to the denoising filter and to the vertical and horizontal combiners configured to switch between a deblocking mode and denoising mode according to the location of the pixel, so that deblocking occurs for pixels in block edge regions.
6 more elements
Dependencies are inferred from the claim text.