Systems and methods for motion detection, quantification, and/or measurement with exposure correction in video-based time-series signals
A system and method for detecting, quantifying, and/or measuring motion of an object and correcting for exposure includes providing a processor and at least one video sensor; determining video recording parameters of the at least one video sensor; recording, by the at least one video sensor, video of the object; extracting a data set from the video wherein the data set describes the motion of the object; calculating a frequency transform of the data set for at least one frequency; and performing exposure correction at the at least one frequency based on the recording parameters.
1. A method for detecting motion of an object and correcting for exposure, comprising:
providing a processor and at least one video sensor;
determining video recording parameters of the at least one video sensor;
recording, by the at least one video sensor, video of the object;
extracting a data set from the video, wherein the data set describes the motion of the object and includes a measurement error;
calculating a frequency transform of the data set for at least one frequency;
performing exposure correction at the at least one frequency based on the recording parameters; and
determining a corrected motion of the object based on the exposure correction;
wherein the motion of the object has a periodic part and the at least one frequency corresponds to a frequency of the periodic part of the motion of the object.
2. The method of claim 1 , further comprising: calculating a frequency spectrum of the data set.
3. The method of claim 2 , further comprising: selecting a frequency of interest and/or receiving a selection of the frequency of interest from the frequency spectrum as the at least one frequency.
4. The method of claim 1 , wherein the data set is a time series digital signal.
5. The method of claim 1 , wherein the data set comprises at least one pixel intensity.
6. The method of claim 5 , further comprising averaging the at least one pixel intensity.
7. The method of claim 1 , wherein exposure correction includes applying a compensation function.
8. The method of claim 1 , wherein exposure correction comprises calculation of a sensitivity function and its reciprocal.
9. The method of claim 1 , wherein the frequency transform is a Fourier transform.
10. The method of claim 2 , further comprising calculating a FFT for the frequency spectrum of the data set.
11. The method of claim 1 , further comprising:
calibrating the at least one video sensor; and
determining a calibration function;
wherein performing exposure correction includes applying the calibration function.
12. The method of claim 11 , wherein calibrating the sensor comprises recording a video of a test object with a known motion magnitude and frequency.
13. The method of claim 11 , further comprising calculating a response function of output-divided-by-input for the sensor at the at least one frequency.
14. The method of claim 1 , wherein an event takes place with respect to the object and the at least one frequency corresponds to an event frequency.
15. The method of claim 1 , wherein the data set describes the motion of the object in the plane perpendicular to the line-of-sight of the video sensor.
16. A method of detecting motion, comprising:
providing a video and recording parameters of the video;
extracting a data set from the video, wherein the data set includes a time series signal describing an event, wherein the event is a motion of an object and wherein the data set includes a measurement error with respect to the motion of the object;
calculating a frequency spectrum of the data set;
selecting a frequency of interest and/or receiving a selection of the frequency of interest from the frequency spectrum;
calculating a frequency transform of the time series signal for the frequency of interest;
performing exposure correction at the frequency of interest using the recording parameters; and
determining an actual motion of the object based on the exposure correction.
17. The method of claim 16 , wherein the motion of the object has a periodic part and the frequency of interest corresponds to a frequency of the periodic part of the motion of the object.
18. The method of claim 16 , wherein exposure correction comprises calculation of a sensitivity function and its reciprocal.
19. A computer program product, comprising a computer readable hardware storage device storing a computer readable program code, the computer readable program code comprising an algorithm that when executed by a computer processor of a computing system implements a method for detecting motion with respect to an object and correcting for exposure, the method comprising:
extracting a data set from a video, wherein the data set includes a time series signal describing an event, wherein the event is a motion of an object and wherein the data set includes a measurement error with respect to the motion of the object;
calculating a frequency spectrum of the data set;
selecting a frequency of interest and/or receiving a selection of the frequency of interest from the frequency spectrum;
calculating a frequency transform of the time series signal for the frequency of interest;
performing exposure correction at the frequency of interest using recording parameters of the video; and
determining an actual motion of the object based on the exposure correction.