Local maxima sub-integer position estimation in video processing
An apparatus include a first circuit and a second circuit. The first circuit may be configured to (i) receive a plurality of sample values from a plurality of images in a video signal and (ii) estimate a plurality of positions of a plurality of maximum values in the images. Each estimation may operate on the sample values in a respective local region oriented parallel to an axis. The second circuit may be configured to track the positions of the maximum values in the images.
1. An apparatus comprising:
a first circuit configured to (i) receive a plurality of sample values from a plurality of images in a video signal and (ii) estimate a plurality of positions of a plurality of maximum values in said images, wherein each estimation operates on said sample values in a respective local region oriented parallel to an axis and said first circuit is further configured to generate a first intermediate value as a first difference between a first sample value of said sample values and a second sample value of said sample values, and a second intermediate value as a second difference between said second sample value and a third sample value of said sample values; and
a second circuit configured to track said positions of said maximum values in said images.
2. The apparatus according to claim 1 , wherein (i) said sample values have an integer resolution spacing and (ii) said positions of said maximum values have a sub-integer resolution.
3. The apparatus according to claim 2 , wherein said positions of said maximum values have a quarter-integer resolution.
4. The apparatus according to claim 1 , wherein (i) said second circuit is further configured to send a command to said first circuit to determine said positions of said maximum values and (ii) said first circuit is further configured to return said positions of said maximum values to said second circuit.
5. The apparatus according to claim 1 , wherein (i) said first circuit is configured to further estimate a plurality of additional positions of a plurality of additional maximum values in said images and (ii) each further estimation operates on said sample values in another local region oriented parallel to another axis.
6. The apparatus according to claim 5 , wherein said second circuit is further configured to track said additional positions of said additional maximum values in said video signal.
7. The apparatus according to claim 1 , wherein (i) said first circuit uses at most 2 K +1 of said sample values in each of said images to estimate said positions of said maximum values and (ii) K is a positive integer value that determines a resolution of said positions of said maximum values.
8. The apparatus according to claim 1 , wherein said first circuit is further configured to (i) generate a sum of said first intermediate value and said second intermediate value and (ii) generate a third difference between said first intermediate value and said second intermediate value.
9. The apparatus according to claim 8 , wherein said first circuit is further configured to determine each of said positions of said maximum values from at most five possible positions based on said sum and said third difference.
10. The apparatus according to claim 8 , wherein said first circuit is further configured to (i) determine if said first difference is greater than said second difference and (ii) determine each of said positions of said maximum values from at most three possible positions based on said sum and said third difference.
11. The apparatus according to claim 1 , wherein (i) said first circuit uses at most 2 (K-1) +1 of said sample values in each of said images to estimate said positions of said maximum values and (ii) K is a positive integer value that determines a resolution of said positions of said maximum values.
12. The apparatus according to claim 1 , wherein said first circuit is further configured to perform a non-maximum suppression operation on said sample values to locate said respective local regions in said images.
13. The apparatus according to claim 1 , wherein said first circuit is further configured to (i) perform a non-minimum suppression operation on said sample values to locate said respective local regions in said images and (ii) invert said sample values prior to estimating said positions of said maximum values.
14. The apparatus according to claim 1 , wherein said apparatus forms part of a video processing system.
15. A method for local maxima position estimation, comprising the steps of:
receiving a plurality of sample values in each of a plurality of images in a video signal;
estimating in a circuit a plurality of positions of a plurality of maximum values in said images, wherein each estimation operates on said sample values in a respective local region oriented parallel to an axis and said circuit is configured to generate a first intermediate value as a first difference between a first sample value of said sample values and a second sample value of said sample values, and a second intermediate value as a second difference between said second sample value and a third sample value of said sample values; and
tracking said positions of said maximum values in said video signal.
16. The method according to claim 15 , further comprising the step of:
performing either (i) a non-maximum suppression operation on said sample values or (ii) a non-minimum suppression operation on said sample values to locate said respective local regions in said images.
17. The method according to claim 15 , wherein (i) said circuit uses at most 2 K +1 of said sample values in each of said images to estimate said positions of said maximum values and (ii) K is a positive integer value that determines a resolution of said positions of said maximum values.
18. The method according to claim 15 , wherein (i) said circuit uses at most 2 (K-1) +1 of said sample values in each of said images to estimate said positions of said maximum values and (ii) K is a positive integer value that determines a resolution of said positions of said maximum values.
19. The method according to claim 15 , wherein (i) said sample values have an integer resolution spacing and (ii) said positions of said maximum values have a sub-integer resolution.
20. An apparatus comprising:
a first circuit configured to (i) receive a plurality of sample values from a plurality of images in a video signal and (ii) estimate a plurality of positions of a plurality of maximum values in said images, wherein each estimation operates on said sample values in a respective local region oriented parallel to an axis and said first circuit is further configured to perform a non-minimum suppression operation on said sample values to locate said respective local regions in said images and invert said sample values prior to estimating said positions of said maximum values; and
a second circuit configured to track said positions of said maximum values in said images.