Method and device for reducing temporal noise for image
AssigneeMtekvision Co., Ltd.
InventorChang-Ki Min
Life of this patent
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Abstract
A temporal noise reduction method and a temporal noise reduction device are provided. The temporal noise reduction device includes a temporal filter unit that performs a temporal filtering operation using pixel values (CP) of an N×M array in a current frame and pixel values (FP) of an N×M array located at the same position in a neighboring frame separated by a distance TP from the current frame and a motion filter unit that detects a motion of a pixel image from the resultant values of the temporal filter unit and that eliminates noise of a motion-abundant pixel value using a spatial filter. It is possible to effectively reduce noise of an image to prevent deterioration in image quality of the image and to improve performance of post-processing techniques.
Claims18
A temporal noise reduction device comprising:
- a temporal filter unit that performs a temporal filtering operation using pixel values (CP) of an N×M array in a current frame and pixel values (FP) of an N×M array located at the same position in a neighboring frame separated by a distance Tp from the current frame;
- and
- a motion filter unit that detects a motion of a pixel image from the resultant values of the temporal filter unit and that eliminates noise of a motion-abundant pixel using a spatial filter,
- wherein the temporal filter unit includes:
- a spatial filter that eliminates noise of a noise-present pixel in the pixel values (CP) of an N×M array in the current frame with reference to the pixel values of neighboring pixels;
- and
- a selective temporal filter that performs the temporal filtering operation only when a first condition is satisfied in which a difference between a first absolute difference (difp) calculated by an expression abs(FP−SF) and a second absolute difference (difc) calculated by an expression abs(CP−SF) using the pixel values (CP) of the N×M array in the current frame, the resultant values (SF) of the spatial filter, and the pixel values (FP) of the N×M array located at the same position in the neighboring frame is equal to or less than a zeroth user-defined value (TH0).
A temporal noise reduction method comprising:
- (a) a digital processor causing a temporal filter unit to perform a temporal filtering operation using pixel values (CP) of an N×M array in a current frame and pixel values (FP) of an N×M array located at the same position in a neighboring frame separated by a distance TP from the current frame and to output the resultant value;
- and
- (b) the digital processor causing a motion filter unit to detect a motion of a pixel image from the resultant values of the temporal filter unit and to eliminate noise of a motion-abundant pixel using a spatial filter,
- wherein the step of (a) includes:
- a step of causing a spatial filter of the temporal filter unit to eliminate noise of a noise-present pixel in the pixel values (CP) of an N×M array in the current frame with reference to the pixel values of neihborin pixels;
- and
- a step of causing a selective temporal filter of the temporal filter unit to perform the temporal filtering operation only when a first condition is satisfied in which a difference between a first absolute difference (difp) calculated by an expression abs(FP−SF) and a second absolute difference (difc) calculated by an expression abs(CP−SF) using the pixel values (CP) of the N×M array in the current frame, the resultant values (SF) of the spatial filter, and the pixel values (FP) of the N×M array located at the same position in the neighboring frame is equal to or less than a zeroth user-defined value (TH0).
Dependencies are inferred from the claim text.