Optical filtering for electronic devices
In one embodiment, a camera includes an image sensor within a camera housing that converts light entering the camera housing through an optical filter into digital image data. The optical filter can have a variable opacity. A processor in communication with the image sensor identifies operation settings for the optical filter and adjusts an opacity level of the optical filter over an exposure period in accordance with the operation settings for the optical filter. In addition, the processor modifies values of the digital image data based at least on the operation settings for the optical filter.
1. An electronic device for capturing video data, the electronic device comprising:
an image sensor configured to generate a first plurality of consecutive image frames and a second plurality of consecutive image frames from light that contacts the image sensor, the light passing through an optical filter prior to arriving at the image sensor; and
one or more processors programmed to:
generate a control signal that changes an opacity level of the optical filter uniformly across the optical filter and sets the opacity level during first image frame periods of the first plurality of consecutive image frames differently from the opacity level during second image frame periods of the second plurality of consecutive image frames, and
modify image data values of the first plurality of consecutive image frames differently from image data values of the second plurality of consecutive image frames to address an effect of the optical filter.
2. The electronic device of claim 1 , wherein the image data values of the first plurality of consecutive image frames and the second plurality of consecutive image frames are associated with a first color, a second color, and a third color, and the one or more processors is programmed to modify the image data values of the first plurality of consecutive image frames differently from the image data values of the second plurality of consecutive image frames by modifying the image data values of the first plurality of consecutive image frames associated with the first color by a greater amount than the image data values of the second plurality of consecutive image frames associated with the first color.
3. The electronic device of claim 2 , wherein the first color is blue, the second color is red, and the third color is green.
4. The electronic device of claim 1 , wherein the one or more processors is programmed to modify the image data values of the first plurality of consecutive image frames and the second plurality of consecutive image frames that are associated with a first color rather than a second color to address the effect of the optical filter.
5. The electronic device of claim 1 , wherein the one or more processors is programmed to modify the image data values of the first plurality of consecutive image frames and the second plurality of consecutive image frames by applying a matrix to the image data values of the first plurality of consecutive image frames and the second plurality of consecutive image frames.
6. The electronic device of claim 1 , wherein the one or more processors is programmed to modify the image data values of the first plurality of consecutive image frames and the second plurality of consecutive image frames to address the effect of the opacity level being set during the first image frame periods differently from during the second image frame periods.
7. The electronic device of claim 1 , wherein the control signal sets the opacity level during the first image frame periods so that the opacity level decreases during a first part of each of the first image frame periods and increases during a second part of each of the first image frame periods.
8. The electronic device of claim 7 , wherein the first part of each of the first image frame periods and the second part of each of the first image frame periods have the same duration.
9. The electronic device of claim 1 , wherein the control signal sets the opacity level during the first image frame periods so that the opacity level varies in a way that diminishes an impact of temporal aliasing.
10. The electronic device of claim 1 , wherein the control signal sets the opacity level during the first image frame periods so that the opacity level remains constant over the first image frame periods.
11. The electronic device of claim 1 , wherein the control signal sets the opacity level during each of the first image frame periods so that the opacity level (i) maintains a first level for a first period of time, (ii) abruptly decreases from the first level to a second level, (iii) maintains the second level for a second period of time, and (iv) abruptly increases from the second level.
12. The electronic device of claim 1 , wherein the control signal sets the opacity level during each of the first image frame periods so that the optical filter serves as a global shutter for the image sensor.
13. The electronic device of claim 1 , further comprising the optical filter, the optical filter comprising a variable opacity liquid crystal.
14. The electronic device of claim 1 , further comprising a housing configured to support the image sensor and the one or more processors.
15. The electronic device of claim 14 , wherein the optical filter is a part of a lens mount releasably connectable to the housing.
16. A method for capturing video data, the method comprising:
generating, with an image sensor, a first plurality of consecutive image frames and a second plurality of consecutive image frames from light that contacts the image sensor, the light passing through an optical filter prior to arriving at the image sensor;
generating, with one or more processors, a control signal that changes an opacity level of the optical filter uniformly across the optical filter and sets the opacity level during first image frame periods of the first plurality of consecutive image frames differently from the opacity level during second image frame periods of the second plurality of consecutive image frames; and
modifying, with the one or more processors, image data values of the first plurality of consecutive image frames differently from image data values of the second plurality of consecutive image frames to address an effect of the optical filter.
17. The method of claim 16 , wherein the image data values of the first plurality of consecutive image frames and the second plurality of consecutive image frames are associated with a first color, a second color, and a third color, and the image data values of the first plurality of consecutive image frames are modified differently from the image data values of the second plurality of consecutive image frames by modifying the image data values of the first plurality of consecutive image frames associated with the first color a greater amount than the image data values of the second plurality of consecutive image frames associated with the first color.
18. The method of claim 16 , wherein the control signal sets the opacity level during the first image frame periods so that the opacity level decreases during a first part of each of the first image frame periods and increases during a second part of each of the first image frame periods, and the control signal sets the opacity level during the second image frame periods so that the opacity level remains constant over the second image frame periods.
19. The method of claim 16 , wherein the control signal sets the opacity level during the first image frame periods so that the opacity level varies in a way that diminishes an impact of temporal aliasing during the first image frame periods, and the control signal sets the opacity level during each of the second image frame periods so that during each of the second image frame periods the opacity level (i) maintains a first level for a first period of time, (ii) abruptly decreases from the first level to a second level, (iii) maintains the second level for a second period of time, and (iv) abruptly increases from the second level.
20. The method of claim 16 , wherein the control signal sets the opacity level during the first image frame periods so that the optical filter serves as a global shutter for the image sensor during the first image frame periods, and the control signal sets the opacity level during the second image frame periods so that the optical filter serves as a neutral density filter for the image sensor during the second image frame periods.