Dynamic synchronization of frame rate to a detected cadence in a time lapse image sequence
A frame rate is synchronized to a detected cadence in order to generate an output image sequence that is substantially stabilized. In an in-camera process, a camera receives motion data of the camera while the camera captures the sequence of image frames. A dominant frequency of motion is determined and the capture frame rate is dynamically adjusted to match the frequency of detected motion so that each image frame is captured when the camera is at approximately the same position along the axis of motion. Alternatively, in a post-processing process, frames of a captured image sequence are selectively sampled at a sampling rate corresponding to the dominant frequency of motion so that each sampled frame corresponds to an image capture that occurred when the camera is at approximately the same position along the axis of motion.
1. A method, comprising:
determining motion data of a camera during capture of a time lapse image sequence according to an initial frame rate, the motion data determined using one or more sensors tracking motion of the camera while the camera captures the time lapse image sequence;
converting the motion data from time domain data to frequency domain data;
determining a dominant frequency in the frequency domain data;
determining a modified frame rate using the dominant frequency;
capturing the time lapse image sequence according to the modified frame rate; and
storing the time lapse image sequence to a storage medium.
2. The method of claim 1 , wherein the motion data in a predefined time window is converted from time domain data to frequency domain data.
3. The method of claim 1 , wherein the motion data comprises position data along an axis of oscillation.
4. The method of claim 1 , wherein converting the motion data from the time domain data to the frequency domain data is performed using Fast Fourier Transform.
5. The method of claim 1 , wherein determining the dominant frequency in the frequency domain data comprises:
determining a frequency value in the frequency domain data that has the largest amplitude of the plurality of frequency values in the frequency domain data; and
selecting the frequency value as the dominant frequency.
6. The method of claim 1 , wherein determining the modified frame rate using the dominant frequency comprises:
setting the modified frame rate to match the dominant frequency.
7. A non-transitory computer-readable storage medium storing instructions for dynamic synchronization of frame rate, the instructions when executed by one or more processors cause the one or more processors to:
record motion information of a camera during capture of an image sequence according to an initial frame rate, the motion information recorded by one or more sensors of the camera while the camera captures the image sequence;
convert the motion information from time domain representation to frequency domain data;
determine a dominant frequency in the frequency domain data;
determine a modified frame rate using the dominant frequency; and
continue capture of the image sequence according to the modified frame rate.
8. The non-transitory computer-readable storage medium of claim 7 , wherein the motion information in a predefined time window is converted from the time domain data to the frequency domain data.
9. The non-transitory computer-readable storage medium of claim 7 , wherein the motion information comprises position data along an axis of oscillation.
10. The non-transitory computer-readable storage medium of claim 7 , wherein the conversion of the motion information from the time domain representation to the frequency domain data is performed using Fast Fourier Transform.
11. The non-transitory computer-readable storage medium of claim 7 , wherein the computer-readable storage medium stores further instructions for the determination of the dominant frequency in the frequency domain data, the instructions when executed by the one or more processors cause the one or more processors to:
determine a frequency value in the frequency domain data that has the largest amplitude of the plurality of frequency values in the frequency domain data; and
select the frequency value as the dominant frequency.
12. The non-transitory computer-readable storage medium of claim 7 , wherein the computer-readable storage medium stores further instructions for the determination of the modified frame rate using the dominant frequency, the instructions when executed by the one or more processors cause the one or more processors to:
set the modified frame rate to match the dominant frequency.
13. A camera for dynamic selection of a frame interval during image sequence capture, the camera comprising:
one or more processors; and
a non-transitory computer-readable storage medium storing instructions, the instructions when executed by the one or more processors causing the one or more processors to:
initiate capture of an image sequence according to an initial frame interval;
obtain a frequency of camera motion during the capture of the image sequence;
determine a modified frame interval using the frequency of camera motion; and
continue capture of the image sequence according to the modified frame interval.
14. The camera of claim 13 , wherein the frequency of camera motion is converted from time domain representation to frequency domain data.
15. The camera of claim 13 , wherein the frequency of camera motion includes position data along an axis of oscillation.
16. The camera of claim 14 , wherein the conversion of the frequency of camera motion from the time domain representation to the frequency domain data is performed using Fast Fourier Transform.
17. The camera of claim 14 , wherein the non-transitory computer-readable storage medium stores further instructions that when executed by the one or more processors cause the one or more processors to:
determine a frequency value in the frequency domain data that has the largest amplitude of the plurality of frequency values in the frequency domain data; and
select the frequency value as a dominant frequency.
18. The camera of claim 17 , wherein the non-transitory computer-readable storage medium stores further instructions that when executed by the one or more processors cause the one or more processors to:
set the modified frame interval to match the dominant frequency.
19. The camera of claim 13 , wherein the camera is removably attachable to a user or object in motion.