Methods and apparatus to count people in images
View Patent ↗Methods and apparatus to count people in images are disclosed. An example method includes generating a first fluctuation factor for a first frame by averaging fluctuation values of a random set of pixels of the first frame; generating a second fluctuation factor for a person indication area of the first frame by averaging fluctuation values of pixels of the person indication area; and marking the person indication area as a false positive when the second fluctuation factor is less than or equal to the first fluctuation factor.
1. A method, comprising:
generating, with a random number generator, a random subset of pixels of a first frame, the random subset of pixels including less than all of the pixels of the first frame;
generating, via a processor, a first fluctuation factor for the first frame by averaging fluctuation values of the random subset of pixels of the first frame;
identifying, via the processor, a person indication area in which a person is believed to be located, the person indication area corresponding to a subset of the pixels of the first frame including less than all of the pixels of the first frame;
generating, via the processor, a second fluctuation factor for the person indication area of the first frame by averaging fluctuation values of the subset of the pixels corresponding to the person indication area; and
marking, via the processor, the person indication area as corresponding to a false positive when the second fluctuation factor is less than or equal to the first fluctuation factor.
2. A method as defined in claim 1 , wherein identifying the person indication area further includes calculating a location of the person indication area in the first frame.
3. A method as defined in claim 2 , further including querying a database with the calculated location to determine whether a person was detected at the calculated location in previous frames captured within a threshold amount of time from capture of the first frame.
4. A method as defined in claim 3 , further including unmarking the person indication area as a false positive when the query indicates that at least one of the previous frames includes a detection of a person at the calculated location.
5. A method as defined in claim 3 , further including verifying the person indication area as a false positive when the query indicates that the previous frames do not include a detection of a person at the calculated location.
6. A method as defined in claim 1 , wherein the generating of the first fluctuation factor includes performing root mean square calculations.
7. A method as defined in claim 6 , wherein the root mean square calculations are based on pixel intensities.
8. A tangible computer readable storage medium comprising instructions that, when executed, cause a machine to at least:
generate a random subset of pixels of a first frame, the random subset of pixels including less than all of the pixels of the first frame;
generate a first fluctuation factor for the first frame by averaging fluctuation values of the random subset of pixels of the first frame;
identify a person indication area in which a person is believed to be located, the person indication area corresponding to a subset of the pixels of the first frame including less than all of the pixels of the first frame;
generate a second fluctuation factor for the person indication area of the first frame by averaging fluctuation values of the subset of the pixels corresponding to the person indication area; and
identify the person indication area as corresponding to a false positive when the second fluctuation factor is less than or equal to the first fluctuation factor.
9. A tangible computer readable storage medium as defined in claim 8 , wherein the instructions, when executed, cause the machine to calculate a location of the person indication area in the first frame.
10. A tangible computer readable storage medium as defined in claim 9 , wherein the instructions, when executed, cause the machine to query a database with the calculated location to determine whether a person was detected at the calculated location in previous frames captured within a threshold amount of time from capture of the first frame.
11. A tangible computer readable storage medium as defined in claim 10 , wherein the instructions, when executed, cause the machine to reverse the identification of the person indication area as a false positive when the query indicates that at least one of the previous frames includes a detection of a person at the calculated location.
12. A tangible computer readable storage medium as defined in claim 10 , wherein the instructions, when executed, cause the machine to verify the person indication area as a false positive when the query indicates that the previous frames do not include a detection of a person at the calculated location.
13. A tangible computer readable storage medium as defined in claim 8 , wherein the instructions cause the machine to generate the first fluctuation factor by performing root mean square calculations.
14. A tangible computer readable storage medium as defined in claim 13 , wherein the root mean square calculations are based on pixel intensities.
15. An apparatus, comprising:
a processor to:
generate a random subset of pixels of a first frame, the random subset of pixels including less than all of the pixels of the first frame;
generate a first fluctuation factor for the first frame by averaging fluctuation values of the random subset of pixels of the first frame; and
identify a person indication area in which a person is believed to be located, the person indication area corresponding to a subset of the pixels of the first frame including less than all of the pixels of the first frame;
generate a second fluctuation factor for the person indication area of the first frame by averaging fluctuation values of the subset of the pixels corresponding to the person indication area; and
a comparator to identify the person indication area as corresponding to a false positive when the second fluctuation factor is less than or equal to the first fluctuation factor.
16. An apparatus as defined in claim 15 , further including a location calculator to determine a location of the person indication area in the first frame.
17. An apparatus as defined in claim 16 , further including a checker to query a database with the calculated location to determine whether a person was detected at the calculated location in previous frames captured within a threshold amount of time from capture of the first frame.
18. An apparatus as defined in claim 17 , wherein the checker is to reverse the identification of the person indication area as a false positive when the query indicates that at least one of the previous frames includes a detection of a person at the calculated location.
19. An apparatus as defined in claim 17 , wherein the checker is to verify the person indication area as a false positive when the query indicates that the previous frames do not include a detection of a person at the calculated location.
20. An apparatus as defined in claim 15 , wherein the processor is to generate the first fluctuation via root mean square calculations based on pixel intensities.