Camera-based lighting control

1. A camera-based sensor device for use in a controllable lighting system, the camera-based sensor comprising:

a communications interface;

a camera for capturing images of a scene, each image comprising an array of pixels; and

a processor configured to:

determine at least one light performance indicator, LPI, from an image captured by the camera, the LPI being a combined lighting metric derived from a plurality of pixels of the array of pixels in the image; and

transmit, via the communications interface, the determined at least one LPI to the controllable lighting system for use by the controllable lighting system to make a control decision based on the LPI, wherein the processor does not transmit any of the images of the scene;

wherein the processor is configured to determine the at least one LPI for each of a plurality of users present within the scene; and

wherein the processor is configured to determine a location and orientation of a user of the plurality of users present within the scene.

2. The camera-based sensor device according to claim 1 , wherein at least one of the LPIs is a brightness LPI indicating a brightness value over a plurality of pixels in an image captured by the camera.

3. The camera-based sensor device according to claim 1 , wherein at least one of the LPIs is a contrast LPI indicating a difference in brightness over a plurality of pixels in an image captured by the camera.

4. The camera-based sensor device according to claim 1 , wherein at least one of the LPIs is a color LPI indicating a color value over a plurality of pixels in an image captured by the camera.

5. The camera-based sensor device according to claim 1 , wherein at least one the LPIs is a color contrast LPI indicating a difference in color over a plurality of pixels in an image captured by the camera.

6. The camera-based sensor device according to claim 1 , wherein at least one of the LPIs is a non-visual LPI indicating an expected non-visual effect on a user present within the scene.

7. The camera-based sensor device according to claim 1 , wherein at least one of the LPIs is a glare LPI indicating an amount of glare experienced by the user.

8. The camera-based sensor device according to claim 1 , wherein the processor is configured to determine a luminance distribution from the array of pixels, and wherein at least one of the LPIs is a luminance LPI indicating a luminance value over a plurality of pixels in an image captured by the camera.

9. The camera-based sensor device according to claim 1 , wherein the scene comprises a plurality of task areas, and an LPI is determined for each respective task area.

10. A camera-based sensor device for use in a controllable lighting system, the camera-based sensor comprising:

a communications interface;

a camera for capturing images of a scene, each image comprising an array of pixels; and

a processor configured to:

determine at least one light performance indicator, LPI, from an image captured by the camera, the LPI being a combined lighting metric derived from a plurality of pixels of the array of pixels in the image; and

transmit, via the communications interface, the determined at least one LPI to the controllable lighting system for use by the controllable lighting system to make a control decision based on the LPI, wherein the processor does not transmit any of the images of the scene;

wherein the processor is configured to determine the at least one LPI for each of a plurality of users present within the scene; and

wherein the processor is configured to determine an LPI of the same type for each of a plurality of assumed user locations within the scene and generate an average LPI from the plurality of LPIs.

11. The camera-based sensor device according to claim 1 , wherein the processor is configured to determine a current activity being performed by a user present within the scene, and wherein at least one LPI is dependent on the determined current activity.

12. A method of controlling a controllable lighting system, the method comprising:

capturing an image of a scene using a camera of a camera-based sensor device, the image comprising an array of pixels;

determining by a processor of the camera-based sensor device at least one light performance indicator, LPI, from the image captured by the camera, the LPI being a combined lighting metric derived from a plurality of pixels of the array of pixels in the image; and

transmitting via a communications interface of the camera-based sensor device the determined at least one LPI and not the image from the camera to the controllable lighting system for use by the controllable lighting system to make a control decision based on the LPI,

wherein the determining comprises determining the at least one LPI for each of a plurality of users present within the scene, and wherein the determining comprises determining a location and orientation of a user of the plurality of users present within the scene.

13. The method according to claim 12 , comprising:

receiving the at least one LPI at a controller of the controllable lighting system;

comparing the received at least one LPI with a corresponding user preference to determine a setting for a device in the controllable lighting system; and

controlling the device in accordance with the determined setting.

14. The method according to claim 13 , comprising determining a user satisfaction with the setting for the device in the controllable lighting system; and modifying the corresponding user preference accordingly.