ToF sensor including duel emitting units and method for controlling thereof
Provided is a time of flight (ToF) sensor and a method for controlling the ToF sensor. The ToF sensor includes a first light emitter configured to output first light of a first pattern, a second light emitter configured to output second light of a second pattern, an image sensor including a plurality of pixels, and at least one processor configured to control the first light emitter and the second light emitter to sequentially output the first light and the second light, obtain, based on the output first light and second light being received through the image sensor by being reflected by a plurality of objects, a first image frame corresponding to the received first light and a second image frame corresponding to the received second light, and identify distances between the ToF sensor and the plurality of objects based on the first image frame and the second image frame.
1. A time of flight (ToF) sensor comprising:
a first light emitter configured to output first light having a first pattern;
a second light emitter configured to output second light having a second pattern;
an image sensor comprising a plurality of pixels; and
at least one processor configured to:
control the first light emitter and the second light emitter to sequentially output the first light and the second light,
obtain, based on the output first light and the output second light being received through the image sensor by being reflected by a plurality of objects, a first image frame corresponding to the received first light and a second image frame corresponding to the received second light,
identify distances between the ToF sensor and the plurality of objects based on the first image frame and the second image frame,
identify, based on a plurality of pixel values included in the first image frame, a first area corresponding to an object from among the plurality of objects in the first image frame, a first distance between the object and the ToF sensor being less than a pre-set distance,
determine an exposure time of the image sensor for the second light based on a plurality of first pixel values included in remaining areas excluding the first area in the first image frame, and
obtain, based on the second light being output through the second light emitter, the second image frame by receiving the second light reflected by the plurality of objects through the image sensor based on the exposure time.
2. The ToF sensor of claim 1 , wherein the at least one processor is further configured to:
identify the first distance between the object and the ToF sensor based on the plurality of pixel values included in the first image frame, and
identify a second distance between an object from among the plurality of objects, and the ToF sensor based on the plurality of pixel values included in the second image frame, the second distance being greater than or equal to the pre-set distance.
3. The ToF sensor of claim 1 , wherein the at least one processor is further configured to:
obtain distance values corresponding to each of the plurality of pixels of the image sensor based on each of the plurality of pixel values included in the first image frame, and
identify the first area corresponding to the object from the first image frame based on the distance values.
4. The ToF sensor of claim 3 , wherein the at least one processor is further configured to:
identify an average value of the plurality of pixel values included in the remaining areas in the first image frame, and determine the exposure time of the image sensor for the second light based on the identified average value and a pre-set target brightness value.
5. The ToF sensor of claim 1 , wherein the at least one processor is further configured to:
determine an exposure time of the image sensor for the first light based on the plurality of pixel values included in the second image frame obtained based on the plurality of pixel values included in the first image frame and the exposure time, and
obtain, based on the first light being output through the first light emitter, the first image frame by receiving the first light reflected by the plurality of objects through the image sensor based on the exposure time.
6. The ToF sensor of claim 5 , wherein the at least one processor is further configured to:
identify a second area having a saturated pixel value from the second image frame based on the plurality of pixel values included in the second image frame, and
determine the exposure time of the image sensor for the first light based on sizes of the first area and the second area.
7. The ToF sensor of claim 6 , wherein the at least one processor is further configured to:
determine, based on a size of the first area being smaller than a size of the second area, the exposure time of the image sensor for the first light as a value smaller than a previous exposure time for the first light, and
determine, based on the size of the first area being greater than the size of the second area, the exposure time of the image sensor for the first light as a value greater than the previous exposure time for the first light.
8. A method for controlling a time of flight (ToF) sensor, the method comprising:
sequentially outputting a first light of a first pattern which is generated through a first light emitter and a second light of a second pattern which is generated through a second light emitter,
obtaining a first image frame corresponding to the first light and a second image frame corresponding to the second light by receiving the first light and the second light reflected by a plurality of objects through an image sensor; and
identifying distances between the ToF sensor and the plurality of objects based on the first image frame and the second image frame,
wherein the obtaining the first image frame and the second image frame comprises:
outputting the first light through the first light emitter;
obtaining the first image frame corresponding to the first light by receiving the first light reflected by the plurality of objects through the image sensor;
identifying a first area corresponding to an object from among the plurality of objects in the first image frame based on a plurality of pixel values included in the first image frame, a first distance between the object and the ToF sensor being less than a pre-set distance;
determining an exposure time of the image sensor for the second light based on a plurality of first pixel values included in remaining areas excluding the first area in the first image frame;
outputting the second light through the second light emitter; and
obtaining the second image frame by receiving the second light reflected by the plurality of objects through the image sensor based on the exposure time.
9. The method of claim 8 , wherein the identifying distances between the ToF sensor and the plurality of objects comprises:
identifying the first distance between the object and the ToF sensor based on the plurality of pixel values included in the first image frame, and
identifying a second distance between an object and the ToF sensor based on a plurality of pixel values included in the second image frame, the second distance being greater than or equal to the pre-set distance from among the plurality of objects.
10. The method of claim 8 , wherein the identifying the first area comprises:
obtaining distance values corresponding to each of the pixels of the image sensor based on each of the plurality of pixel values included in the first image frame; and
identifying the first area corresponding to the object in the first image frame based on the distance values.
11. The method of claim 10 , wherein the determining the exposure time of the image sensor for the second light comprises:
identifying an average value of the plurality of pixel values included in the remaining areas in the first image frame, and
determining the exposure time of the image sensor for the second light based on the average value and a pre-set target brightness value.
12. The method of claim 8 , further comprising:
determining the exposure time of the image sensor for the first light based on the plurality of pixel values included in the second image frame obtained based on the plurality of pixel values included in the first image frame and the exposure time; and
obtaining, based on the first light being output through the first light emitter, the first image frame by receiving the first light reflected by the plurality of objects through the image sensor based on the exposure time.
13. The method of claim 12 , further comprising:
identifying a second area having a saturated pixel value in the second image frame based on the plurality of pixel values included in the second image frame; and
determining the exposure time of the image sensor for the first light based on sizes of the first area and the second area.
14. The method of claim 13 , wherein the determining the exposure time of the image sensor for the first light comprises:
determining, based on a size of the first area being smaller than a size of the second area, the exposure time of the image sensor for the first light as a value smaller than a previous exposure time for the first light, and
determining, based on the size of the first area being greater than the size of the second area, the exposure time of the image sensor for the first light as a value greater than the previous exposure time for the first light.