Post de-interlacer motion adaptive filter for smoother moving edges
View Patent ↗A system and method for motion adaptively filtering a de-interlaced video signal. This motion adaptive filtering may be accomplished by using a motion value determined during motion adaptive de-interlacing. The motion value may be used to adjust the amount of filtering to be applied to the de-interlaced signal. Edges in the signal representing motion my be filtered more than static regions. A pixel by pixel difference between multiple signal frames, calculated during motion adaptive de-interlacing, may be used to determine the motion value. A motion adaptive filter may be implemented either separately from the motion adaptive de-interlacer or incorporated as part of the motion adaptive de-interlacer.
1. A method comprising:
motion adaptively de-interlacing an interlaced video signal, including
determining a motion value for each edge of a plurality of edges represented in the interlaced video signal, wherein the motion value for each edge of the plurality of edges corresponds to whether the edge is in motion within the interlaced video signal,
comparing the motion value of each edge of the plurality of edges to a predetermined threshold value, wherein i) portions of the interlaced video signal representing edges in motion have edges whose motion value is above the predetermined threshold value, and ii) portions of the interlaced video signal not representing edges in motion have edges whose motion value is below the predetermined threshold,
de-interlacing the portions of the interlaced video signal representing edges in motion in accordance with spatial interpolation, and
de-interlacing the portions of the interlaced video signal not representing edges in motion in accordance with temporal interpolation; and
motion adaptively filtering the de-interlaced video signal, including
filtering, in accordance with a first amount, the edges of the plurality of edges whose motion value is above the predetermined threshold value, and
filtering, in accordance with a second amount, the edges of the plurality of edges whose motion value is below the predetermined threshold value,
wherein the first amount is greater than the second amount; and
scaling the motion adaptively filtered de-interlaced video signal and outputting the scaled video directly as a progressive signal or indirectly as a film or interlaced signal by using an interlacer after scaling.
2. The method of claim 1 wherein the motion value comprises a pixel by pixel difference between a plurality of frames in the interlaced video signal.
3. The method of claim 1 wherein the motion adaptively filtering comprises low-pass filtering.
4. The method of claim 1 wherein the motion adaptively filtering comprises tunably filtering such that the motion adaptively filtering is adjustable by a sharpness factor.
5. The method of claim 1 further comprising
determining if the interlaced video signal is film material, and wherein the amount of motion-adaptively filtering the de-interlaced video signal is set to zero if the interlaced video signal is film material.
6. The method of claim 1 wherein the interlaced video signal is a luminance signal, a chrominance signal, a progressive scan signal or an interlaced signal.
7. A system comprising:
a motion adaptive de-interlacer configured to receive and de-interlace an interlaced video signal by
determining a motion value for each edge of a plurality of edges represented in the interlaced video signal, wherein the motion value for each edge of the plurality of edges corresponds to whether the edge is in motion within the interlaced video signal,
comparing the motion value of each edge of the plurality of edges to a predetermined threshold value, wherein i) portions of the interlaced video signal representing edges in motion have edges whose motion value is above the predetermined threshold value, and ii) portions of the interlaced video signal not representing edges in motion have edges whose motion value is below the predetermined threshold,
de-interlacing the portions of the interlaced video signal representing edges in motion in accordance with spatial interpolation, and
de-interlacing the portions of the interlaced video signal not representing edges in motion in accordance with temporal interpolation; and
a motion adaptive filter configured to filter the de-interlaced video signal by
filtering, in accordance with a first amount, the edges of the plurality of edges whose motion value is above the predetermined threshold value, and
filtering, in accordance with a second amount, the edges of the plurality of edges whose motion value is below the predetermined threshold value,
wherein the first amount is greater than the second amount; and
scaling the motion adaptively filtered de-interlaced video signal and outputting the scaled video directly as a progressive signal or indirectly as a film or interlaced signal by using an interlacer after scaling.
8. The system of claim 7 wherein the motion adaptive filter comprises a low-pass filter.
9. The system of claim 7 wherein the motion adaptive filter acquires the motion value from the motion adaptive de-interlacer.
10. The system of claim 9 wherein the motion value is calculated as a pixel by pixel difference between a plurality of frames of the interlaced video signal.
11. The system of claim 7 wherein the motion adaptive filter is part of the motion adaptive de-interlacer.
12. The system of claim 7 wherein the motion adaptive filter is combined with a spatial filter as part of the motion adaptive de-interlacer.
13. The system of claim 12 further comprising a vertical low pass filter combined with the motion adaptive filter.
14. The system of claim 12 wherein the spatial filter is an edge adaptive spatial de-interlacer and the motion adaptive filter combined with the edge adaptive spatial de-interlacer is an edge adaptive filter.
15. The system of claim 7 wherein the interlaced video signal is a progressive scan signal, an interlaced signal, a luminance signal or a chrominance signal.
16. The system of claim 7 wherein the motion adaptive filter receives a film input flag from the motion adaptive de-interlacer and responsive to the film input flag, upon recognition of film input, the motion adaptive filter does not alter the film input.
17. The method of claim 1 , wherein the spatial interpolation is accomplished using pixels from the surrounding frame to fill in interpolated areas, and wherein the temporal interpolation is accomplished using pixels from a neighboring frame to fill in interpolated areas.
18. The system of claim 7 , wherein the spatial interpolation is accomplished using pixels from the surrounding frame to fill in interpolated areas, and wherein the temporal interpolation is accomplished using pixels from a neighboring frame to fill in interpolated areas.