Imaging device that continuously monitor a subject while reducing power consumption needed to illuminate the subject
Power consumption needed to illuminate a subject is reduced and the subject is continuously monitored. Each of a plurality of light sources emits light to the subject. An imaging circuitry obtains a captured image by imaging the subject. A controller performs light emission control to change a light source that emits light from among the plurality of light sources and causes the imaging circuitry to image the subject. A determiner determines whether a detection target that is pre-determined exists in an image area that is a part of the captured image obtained by the imaging circuitry and corresponds to the light source that emits light during imaging for obtaining the captured image.
1. An imaging device comprising:
a plurality of light sources;
an imaging circuitry configured to capture an image of an image area; and
a processing circuit configured to:
sequentially select a group of light sources from among the plurality of light sources,
sequentially control the group of light sources to emit light, each light source of the group of light sources emitting light to a respective portion of the image area,
control the imaging circuitry to capture images of respective portions of the image area to which the light is emitted,
identify whether a detection target exists in each image of the images of the respective portions of the image area,
perform selective light emission control of the plurality of light sources based on identifying whether the detection target exists in each portion of the image area,
based on identifying that the detection target does not exist in the images of the respective portions of the image area, control the plurality of light sources to continue to emit the light to the image area based on a pre-determined light emission order, and
based on identifying that the detection target exists in the images of the respective portions of the image area, increase a light emission frequency of light sources corresponding to the images of the respective portions of the image area in which the detection target exists.
2. The imaging device of claim 1 , wherein the processing circuit is further configured to:
based on identifying that the detection target exists in the images of the respective portions of the image area, alternately control the light sources corresponding to the images of the respective portions of the image area for which the detection target exists and light sources for which the detection target does not exist in the image area among the plurality of light sources to emit the light to the image area based on the pre-determined light emission order.
3. The imaging device of claim 2 , wherein the processing circuit is further configured to control the light sources corresponding to the images of the respective portions of the respective portions of the image area for which the detection target exists to simultaneously emit the light.
4. The imaging device of claim 2 , wherein the processing circuit is further configured to control the light sources corresponding to the images of the respective portions of the respective portions of the image area for which the detection target exists to sequentially emit the light.
5. The imaging device of claim 1 , further comprising a detector configured to perform object detection on a pre-determined object in the image area.
6. The imaging device of claim 5 , wherein, when a portion that is a part of an attention area that is the image area identified to include the detection target is an edge portion of the attention area, the processing circuit is further configured to detect the pre-determined object from a candidate area comprising the attention area and an adjacent area that is an image area adjacent to the edge portion of the attention area.
7. The imaging device of claim 5 , further comprising an identifier configured to extract an object area that is a part of the image area and comprises the pre-determined object detected by the detector, and identify the pre-determined object by combining the object area with a combination image that is pre-registered.
8. The imaging device of claim 7 , wherein, when the object area extracted by the identifier extends over an attention area of the image area identified to include the detection target and an adjacent area that is an image area adjacent to an edge portion of the attention area, the processing circuit is further configured to cause the imaging circuitry to image the image area by causing light sources corresponding to the attention area from among the plurality of light sources and light sources corresponding to the adjacent area from among the plurality of light sources to emit the light, and
the identifier is further configured to combine the object area with the combination image by extracting the object area from the images obtained by the imaging circuitry when the light sources corresponding to the attention area emit the light, combine the object area with the combination image by extracting the object area from the image obtained by the imaging circuitry when the light sources corresponding to the attention area and the adjacent area emit the light, and identify the pre-determined object based on a combination result.
9. The imaging device of claim 1 , wherein the imaging circuitry is further configured to be driven by a rolling shutter method,
the processing circuit is further configured to control the group of light sources to emit the light so that a turn-on period when at least one light source from among the plurality of light sources is turned on and a turn-off period when the at least one light source is turned off exist in a period other than a period when all lines of the imaging circuitry are simultaneously exposed, and
the processing circuit is further configured to identify whether the detection target exists in the image area corresponding to the period when the at least one light source is turned on.
10. The imaging device of claim 9 , wherein the processing circuit is further configured to:
based on identifying that the detection target does not exist in an image of a portion of the image area the images of the respective portions of the image area, control a next light source among the group of light sources of the plurality of light sources to emit the light to the image area based on the pre-determined light emission order and a turn-on order, and
based on identifying that the detection target exists in the images of the respective portions of the image area, increase a frequency at which light sources corresponding to the images of the respective portions of the image area are turned on in the turn-on period.
11. The imaging device of claim 10 , wherein the processing circuit is further configured to:
based on identifying that the detection target exists in the images of the respective portions of the image area, alternately control light sources corresponding to the images of the respective portions of the respective portions of the image area for which the detection target exists and light sources for which the detection target does not exist in the image area among the plurality of light sources to emit the light to the image area based on the pre-determined light emission order.
12. The imaging device of claim 11 , wherein the processing circuit is further configured to control the light sources corresponding to the images of the respective portions of the respective portions of the image area for which the detection target exists to simultaneously emit the light.
13. The imaging device of claim 11 , wherein the processing circuit is further configured to control the light sources corresponding to the images of the respective portions of the respective portions of the image area for which the detection target exists to sequentially emit the light.
14. The imaging device of claim 1 , wherein the processing circuit is further configured to set a light emission amount of the group of light sources based on a brightness of the image area.
15. The imaging device of claim 1 , wherein the processing circuit is further configured to:
set a light emission amount of the group of light sources from among a plurality of light emission amounts in a pre-determined order.
16. The imaging device of claim 1 , wherein the imaging circuitry is further configured to change an exposure time for capturing the image area, and
the processing circuit is further configured to set a light emission amount of the group of light sources and the exposure time of the imaging circuitry.
17. The imaging device of claim 1 , wherein the imaging circuitry is further configured to be driven by a rolling shutter method, and
the processing circuit is further configured to:
control the group of light sources to emit the light so that a period when at least one light source from among the plurality of light sources is turned on and a period when the at least one light source is turned off exist in a period other than a period when all lines of the imaging circuitry are simultaneously exposed, and
determine the image area based on the period when the at least one light source is turned on.
18. The imaging device of claim 17 , wherein the image area is divided into a plurality of row areas and a plurality of column areas,
wherein each column area from among the plurality of column areas corresponds to a light source among the plurality of light sources, and
each row area from among the plurality of row areas corresponds to the period when the at least one light source is turned on.
19. An imaging method using a plurality of light sources that each emit light to an image area, the imaging method comprising:
sequentially selecting a group of light sources from among the plurality of light sources;
sequentially controlling the group of light sources to emit light, each light source of the group of light sources emitting light to a respective portion of the image area;
capturing images of respective portions of the image area to which the light is emitted;
identifying whether a detection target exists in each image of the images of the respective portions of the image area;
performing selective light emission control of the plurality of light sources based on identifying whether the detection target exists in each portion of the image area;
based on identifying that the detection target does not exist in the images of the respective portions of the image area, controlling the plurality of light sources to continue to emit the light to the image area based on a pre-determined light emission order, and
based on identifying that the detection target exists in the images of the respective portions of the image area, increasing a light emission frequency of light sources corresponding to the images of the respective portions of the image area in which the detection target exists.
20. The imaging method of claim 19 , further comprising:
based on identifying that the detection target exists in the images of the respective portions of the image area, alternately controlling the light sources corresponding to the images of the respective portions of the image area for which the detection target exists and light sources for which the detection target does not exist in the image area among the plurality of light sources to emit the light to the image area based on the pre-determined light emission order.
21. The imaging method of claim 20 , further comprising:
controlling the light sources corresponding to the images of the respective portions of the respective portions of the image area for which the detection target exists to simultaneously emit the light.
22. The imaging method of claim 20 , further comprising:
controlling the light sources corresponding to the images of the respective portions of the respective portions of the image area for which the detection target exists to sequentially emit the light.
23. The imaging method of claim 19 , further comprising:
performing object detection on a pre-determined object in the image area.
24. The imaging method of claim 23 , further comprising:
extracting an object area that is a part of the image and comprises the pre-determined object detected from the image, and identifying the pre-determined object by combining the object area with a combination image that is pre-registered.