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US 7,680,355 B2Granted
Detection of artifacts resulting from image signal decompression
AssigneeIntel Corporation
InventorsYi-Jen Chiu, Jorge E. Caviedes
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Abstract
A method includes making a first determination as to whether a current pixel has a value which reflects a mosquito noise artifact, and determining whether to apply a filtering process at the current pixel based on a result of the first determination. In addition, or alternatively, a method includes making a second determination as to whether a current pixel has a value which reflects a ringing artifact, and determining whether to apply a filtering process at the current pixel based on a result of the second determination.
Claims24
A method comprising:
- making a first determination in a noise reduction circuit after decoding of a video signal as to whether a current pixel in the decoded video signal has a value which reflects a mosquito noise artifact;
- and
- determining in the noise reduction circuit whether to apply a filtering process to the decoded video signal at said current pixel based on a result of said first determination;
- wherein said first determination includes comparing a motion metric for the current pixel with a first threshold and with a second threshold that is lower than the first threshold, said current pixel being determined to reflect a mosquito noise artifact if said motion metric is between said first and second thresholds;
- wherein said motion metric is calculated by adding absolute differences between a group of pixels centered on said current pixel and corresponding pixels of a previous image in a sequence of images.
2 more elements
A method comprising:
- making a first determination in a noise reduction circuit after decoding of a video signal as to whether a current pixel in the decoded video signal has a value which reflects a mosquito noise artifact;
- and
- determining in the noise reduction circuit whether to apply a filtering process to the decoded video signal at said current pixel based on a result of said first determination;
- wherein:
- said first determination is made only with respect to selected pixel blocks of an image;
- the selected pixel blocks are selected based at least in part on a pixel block activity metric;
- and
- the activity metric is calculated only for (a) pixel blocks that are a first type of edge blocks and satisfy a first edge criterion;
- and (b) pixel blocks that are adjacent to at least one pixel block that is a second type of edge block and satisfies a second edge criterion that is different from the first edge criterion.
6 more elements
A system comprising:
- a video signal decoder;
- and
- a noise reduction circuit coupled to said video signal decoder and operative to:
- detect that a current pixel in a video signal decoded by the video signal decoder exhibits a mosquito noise artifact;
- and
- in response to detecting that said current pixel exhibits a mosquito noise artifact, apply a filtering process at said current pixel in the video signal decoded by the video signal decoder;
- wherein said detecting includes comparing a motion metric for the current pixel with a first threshold and with a second threshold that is lower than the first threshold, said current pixel being detected to exhibit a mosquito noise artifact if said motion metric is between said first and second thresholds;
- wherein said motion metric is calculated by adding absolute differences between a group of pixels centered on said current pixel and corresponding pixels of a previous image in a sequence of images.
5 more elements
A system comprising:
- a video signal decoder;
- and
- a noise reduction circuit coupled to said video signal decoder and operative to:
- detect that a current pixel in a video signal decoded by the video signal decoder exhibits a mosquito noise artifact;
- and
- in response to detecting that said current pixel exhibits a mosquito noise artifact, apply a filtering process at said current pixel in the video signal decoded by the video signal decoder;
- wherein:
- said detecting is performed only with respect to selected pixel blocks of an image;
- the selected pixel blocks are selected based at least in part on a pixel block activity metric;
- and
- the activity metric is calculated only for (a) pixel blocks that are a first type of edge blocks and satisfy a first edge criterion;
- and (b) pixel blocks that are adjacent to at least one pixel block that is a second type of edge block and satisfies a second edge criterion that is different from the first edge criterion.
9 more elements
Dependencies are inferred from the claim text.