Systems and methods for detection and mitigation of a rolling band using a secondary camera

1 . A computer-implemented method, comprising:

displaying, by a viewfinder, a preview of a video of a scene being captured by a primary camera;

receiving, from an image sensor of a secondary camera, pixel data corresponding to the scene, wherein the primary camera and the secondary camera share a common field of view; and

determining, based on the pixel data from the secondary camera, a presence or an absence of a rolling band in the preview of the video being captured by the primary camera, the method further comprising:

receiving, from an ambient light sensor (ALS), sensor data indicative of an ambient light,

determining a first frequency of the ambient light based on the sensor data,

determining a second frequency of the ambient light based on the pixel data from the image sensor of the secondary camera, and

comparing the first frequency and the second frequency to determine whether there is a mismatch.

2 . The computer-implemented method of claim 1 , further comprising:

determining the presence of the rolling band in the preview of the video; and

adjusting an exposure time for the primary camera to reduce the rolling band in the preview of the video.

3 . The computer-implemented method of claim 1 , wherein the adjusting of the exposure time comprises:

determining whether to increase the exposure time for the primary camera.

4 . The computer-implemented method of claim 3 , wherein the determining of whether to increase the exposure time is based on a determination of whether the increase of the exposure time reduces a dynamic range of the video.

5 . The computer-implemented method of claim 4 , further comprising:

upon a determination that the increase of the exposure time reduces the dynamic range of the video, maintaining the exposure time for the primary camera.

6 . The computer-implemented method of claim 4 , further comprising:

upon a determination that the increase of the exposure time does not reduce the dynamic range of the video, increasing the exposure time for the primary camera.

7 . The computer-implemented method of claim 1 , wherein the secondary camera is maintained at an exposure time that does not exceed a time threshold.

8 . The computer-implemented method of claim 1 , further comprising:

determining that there is a mismatch between the first frequency and the second frequency; and

decreasing a confidence level of a measurement of the ambient light.

9 . The computer-implemented method of claim 1 , further comprising:

determining that a mismatch between the first frequency and the second frequency is within a threshold mismatch value; and

increasing a confidence level of a measurement of the ambient light.

10 . The computer-implemented method of claim 1 , further comprising:

determining that a mismatch between the first frequency and the second frequency exceeds a threshold mismatch value; and

providing a notification that the ALS may have a potential malfunction.

11 . The computer-implemented method of claim 1 , wherein the primary camera and the secondary camera are components of a mobile device.

12 . The computer-implemented method of claim 11 , wherein the primary camera and the secondary camera are located on a same side of the mobile device.

13 . A computing device, comprising:

a primary camera and a secondary camera that share a common field of view;

one or more processors; and

data storage, wherein the data storage has stored thereon computer-executable instructions that, when executed by the one or more processors, cause the computing device to carry out functions comprising:

displaying, by a viewfinder of the computing device, a preview of a video of a scene being captured by the primary camera;

receiving, from an image sensor of the secondary camera, pixel data corresponding to the scene; and

determining, based on the pixel data from the secondary camera, a presence or an absence of a rolling band in the preview of the video being captured by the primary camera, and the functions further comprising:

receiving, from an ambient light sensor (ALS), sensor data indicative of an ambient light,

determining a first frequency of the ambient light based on the sensor data,

determining a second frequency of the ambient light based on the pixel data from the image sensor of the secondary camera, and

comparing the first frequency and the second frequency to determine whether there is a mismatch.

14 . The computing device of claim 13 , wherein the functions comprise:

determining the presence of the rolling band in the preview of the video; and

adjusting an exposure time for the primary camera to reduce the rolling band in the preview of the video.

15 . The computing device of claim 14 , wherein the adjusting of the exposure time is based on a determination of whether an increase of the exposure time reduces a dynamic range of the video.

16 . The computing device of claim 13 , wherein the secondary camera is maintained at an exposure time that does not exceed a time threshold.

17 . The computing device of claim 13 , wherein the primary camera and the secondary camera are located on a same side of the computing device.

18 . The computing device of claim 13 , wherein the functions comprise:

determining that there is a mismatch between the first frequency and the second frequency; and

decreasing a confidence level of a measurement of the ambient light.

19 . The computing device of claim 13 , wherein the functions comprise:

determining that a mismatch between the first frequency and the second frequency is within a threshold mismatch value; and

increasing a confidence level of a measurement of the ambient light.

20 . The computing device of claim 18 , wherein the functions comprise:

determining that a mismatch between the first frequency and the second frequency exceeds a threshold mismatch value; and

providing a notification that the ALS may have a potential malfunction.

21 . An article of manufacture comprising one or more non-transitory computer readable media having computer-readable instructions stored thereon that, when executed by one or more processors of a computing device, cause the computing device to carry out functions comprising:

displaying, by a viewfinder, a preview of a video of a scene being captured by a primary camera;

receiving, from an image sensor of a secondary camera, pixel data corresponding to the scene, wherein the primary camera and the secondary camera share a common field of view; and

determining, based on the pixel data from the secondary camera, a presence or an absence of a rolling band in the preview of the video being captured by the primary camera, and the functions further comprising:

receiving, from an ambient light sensor (ALS), sensor data indicative of an ambient light,

determining a first frequency of the ambient light based on the sensor data,

determining a second frequency of the ambient light based on the pixel data from the image sensor of the secondary camera, and

comparing the first frequency and the second frequency to determine whether there is a mismatch.