Method and apparatus for detecting defects in digitized image sequences
AssigneeThomson Licensing
InventorOliver THEIS
Life of this patent
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Abstract
Dirt or other non-steady defects are detected in a frame of a sequence of digitized image frames. No determination of motion vectors for motion compensation is required. Instead, absolute motion values for a plurality of pixels of the frame relative to a preceding frame and to a succeeding frame of the sequence are determined. Based on the assumption that motion is usually smooth in the sequence, temporal coherence violations between the frame and the preceding frame and between the frame and the succeeding frame are detected for the pixels, depending on the absolute motion values. Pixels of the plurality of pixels are determined as defective if corresponding temporal coherence violations are detected between the frame and the preceding frame and the succeeding frame.
Claims20
Method for detecting defects in a frame of a sequence of digitized image frames, comprising
- determining absolute motion values for a plurality of pixels of the frame relative to a preceding frame and to a succeeding frame of the sequence;
- for the plurality of pixels, detecting temporal coherence violations between the frame and the preceding frame and between the frame and the succeeding frame depending on said absolute motion values;
- and
- determining at least one pixel of the plurality of pixels as defective if corresponding temporal coherence violations are detected between the frame and the preceding frame and the succeeding frame.
Apparatus for detecting defects in a frame of a sequence of digitized image frames, comprising
- an input configured to receive frames of the sequence of digitized image frames;
- a motion determination unit configured to determine absolute motion values for a plurality of pixels of the frame relative to a preceding frame and to a succeeding frame of the sequence;
- a temporal coherence detection unit configured to detect for the plurality of pixels temporal coherence violations between the frame and the preceding frame and between the frame and the succeeding frame depending on said absolute motion values;
- and
- a defect detection unit configured to determine at least one pixel of the plurality of pixels as defective if it detects corresponding temporal coherence violations between the frame and the preceding frame and the succeeding frame.
Apparatus for detecting defects in a frame of a sequence of digitized image frames, comprising
- a processing device and
- a memory device storing instructions that, when executed, cause the apparatus to:
- determine absolute motion values for a plurality of pixels of the frame relative to a preceding frame and to a succeeding frame of the sequence;
- for the plurality of pixels, detect temporal coherence violations between the frame and the preceding frame and between the frame and the succeeding frame depending on said absolute motion values;
- and
- determine at least one pixel of the plurality of pixels as defective if corresponding temporal coherence violations are detected between the frame and the preceding frame and the succeeding frame.
Computer readable storage medium having stored therein instructions enabling detection of defects in a frame of a sequence of digitized image frames, wherein the instructions, when executed by a computer, cause the computer to:
- determine absolute motion values for a plurality of pixels of the frame relative to a preceding frame and to a succeeding frame of the sequence;
- for the plurality of pixels, detect temporal coherence violations between the frame and the preceding frame and between the frame and the succeeding frame depending on said absolute motion values;
- and
- determine at least one pixel of the plurality of pixels as defective if corresponding temporal coherence violations are detected between the frame and the preceding frame and the succeeding frame.
Dependencies are inferred from the claim text.