Method for sensing motion and device for implementing the same

• US 8,724,852 B2
• Filed: 05/14/2012
• Issued: 05/13/2014
• Est. Priority Date: 08/31/2011
• Status: Active Grant

• Current Assignee: Dyna Image Corp. (Diodes Incorporated)
• Original Assignee: Lite-On Semiconductor Corporation (Diodes Incorporated)
• Inventors: Chen, Chih-Hao, Chen, Meng-Kun
• Primary Examiner(s): Patel, Nirav G
• Application Number:
  US13/470,466
• Publication Number:
  US 20130051617A1
• Time in Patent Office: 729 Days
• Field of Search: None
• US Class Current: 382/103
• CPC Class Codes: G06F 3/005 Input arrangements through a video camera
• CPC Class Codes: G06T 2207/10152 Varying illumination
• CPC Class Codes: G06T 7/136 involving thresholding
• CPC Class Codes: G06T 7/246 using feature-based methods, e.g. the tracking of corners or segments

Abstract

A method for sensing a motion of an object is to be implemented by a motion recognition device that includes an image acquiring unit and a processor. In the method, the image acquiring unit is configured to acquire a series of image frames by detecting intensity of light received thereby. The processor is configured to receive at least one of the image frames and to determine whether an object is detected in the at least one of the image frames. When an object is detected, the processor is further configured to receive the image frames from the image acquiring unit, and to determine a motion of the object with respect to a three-dimensional coordinate system according to the image frames thus received.

Claims

1. A method for sensing a motion of an object, said method to be implemented by a motion recognition device that includes an image acquiring unit, a processor, and at least one lighting module for providing a light source, said method comprising the following steps of:

a) configuring the image acquiring unit to acquire continuously a series of image frames by detecting intensity of light received thereby;

b) configuring the processor to receive at least one of the image frames from the image acquiring unit;

c) configuring the processor to;

compute, from at least one of the image frames received in step b), a first luminance value that is associated with ambient light;

compare the first luminance value with a first predetermined threshold value; and

select a first operation mode when the first luminance value is smaller than the first predetermined threshold value;

d) when the first operation mode is selected in step c), configuring the processor to generate a control signal for activating the lighting module, and to determine whether an object is detected by the following sub-steps of;

d11) configuring the image acquiring unit to acquire at least one image frame;

d12) configuring the processor to compute a second luminance value according to said at least one image frame acquired in sub-step d1);

d13) configuring the processor to compare the second luminance value with a second predetermined threshold value; and

d14) when it is determined in sub-step d13) that the second luminance value is larger than the second predetermined threshold value, configuring the processor to determine that the object is detected in said at least one image frame acquired in sub-step d1); and

e) when it is determined in sub-step d14) that the object is detected, configuring the processor to receive the image frames from the image acquiring unit, and to determine a motion of the object with respect to a three-dimensional coordinate system according to the image frames thus received.

2. The method as claimed in claim 1, wherein, when the first operation mode is selected, step e) includes the following sub-steps of:

e1) according to the image frames received in step e), configuring the processor to obtain a series of luminance trace values that are associated with the object detected in the image frames; and

e2) configuring the processor to determine the motion of the object based on the luminance trace values obtained in sub-step e1).

3. The method as claimed in claim 2, the three-dimensional coordinate system including an X axis and a Y axis cooperating to define an image plane, and a Z axis perpendicular to the image plane, wherein:

each of the image frames acquired by the image acquiring unit includes a plurality of pixel data sets;

in sub-step e1), the processor is further configured to calculate a series of average luminance values as the luminance trace values, respectively, each of the average luminance values being based on the pixel data sets of a respective one of the image frames that are received successively in step e); and

in sub-step c2), the processor is configured to determine that the object moves away from the image plane along the Z axis when the luminance trace values decrease with time, and that the object moves toward the image plane along the Z axis when the luminance trace values increase with time.

4. The method as claimed in claim 1, wherein:

in step c), the processor is further configured to select a second operation mode when the first luminance value is larger than the predetermined threshold value;

and in step d), when the second operation mode is selected, the processor is further configured to generate a control signal for deactivating the lighting module of the lighting unit.

5. The method as claimed in claim 4, wherein, when the second operation mode is selected, step d) further includes the following sub-steps of:

d21) configuring the image acquiring unit to acquire at least one image frame;

d22) configuring the processor to calculate a third luminance value from said at least one image frame acquired in sub-step d21);

d23) configuring the processor to compare the third luminance value with a third predetermined threshold value; and

d24) configuring the processor to determine that the object is detected in said at least one image frame acquired in sub-step d21) when the third luminance value is smaller than the predetermined third threshold value.

6. The method as claimed in claim 1, wherein step e) further includes the following steps of:

e3) according to the image frames received in step c), configuring the processor to obtain a series of object range information indicating where the object is detected in the image frames; and

e4) configuring the processor to determine the motion of the object according to the object range information.

7. The method as claimed in claim 1, further comprising a step of:

configuring the processor to obtain a series of color temperature values that are associated with ambient light from the image frames.

8. The method as claimed in claim 1, further comprising a step of:

configuring the processor to obtain a series of brightness values that are associated with ambient light from the image frames.

9. A motion recognition device comprising:

a lighting unit having at least one lighting module for providing a light source at an illumination area;

an image acquiring unit including a photodetector array and an analog-to-digital converter (ADC), said photodetector array including a plurality of photodetectors arranged on a two-dimensional plane and being operable to generate sense signals by detecting intensity of light received thereby, said photodetector array having a detection area, at least a part of which overlaps the illumination area of said at least one lighting module, said ADC being coupled to said photodetector array for receiving the sense signals therefrom and being operable to convert the sense signals into image frames; and

a processor coupled to said ADC of said image acquiring unit and co-operable with said image acquiring unit to implement a method as claimed in claim 1 for determining whether an object is detected in at least one of the image frames and, when the determination is affirmative, determining a motion of the object with respect to a three-dimensional coordinate system according to apart of the image frames that are acquired after acquisition of said at least one of the image frames where the object is detected.

10. The motion recognition device as claimed in claim 9, wherein said processor is operable to obtain object range information that is associated with the object, and to determine the motion of the object based on the object range information thus obtained.

11. The motion recognition device as claimed in claim 9, wherein at least one of said photodetectors includes a color filter, and said processor is operable to obtain color temperature values that are associated with ambient light from the image frames.

12. The motion recognition device as claimed in claim 9, wherein said processor is operable to obtain brightness values that are associated with ambient light from the image frames.

13. A method for sensing a motion of an object, said method to be implemented by a motion recognition device that includes an image acquiring unit, a processor, and at least one lighting module for providing a light source, said method comprising the following steps of:

a) configuring the image acquiring unit to acquire continuously a series of image frames by detecting intensity of light received thereby;

b) configuring the processor to receive at least one of the image frames from the image acquiring unit;

c) configuring the processor to compute, from at least one of the image frames received in step b), a first luminance value that is associated with ambient light, to compare the first luminance value with a first predetermined threshold value, and to select a second operation mode when the first luminance value is larger than the first predetermined threshold value;

d) when the second operation mode is selected in step c), configuring the processor to generate a control signal for deactivating the lighting module, to receive at least one of the image frames, and to determine whether an object is detected in said at least one of the image frames; and

e) when the determination made in step d) is affirmative, configuring the processor to receive the image frames from the image acquiring unit, and to determine a motion of the object with respect to a three-dimensional coordinate system according to the image frames thus received.

14. The method as claimed in claim 13, wherein, in step d), the processor is configured to determine whether an object is detected by the following sub-steps of:

d1) configuring the image acquiring unit to acquire at least one image frame;

d2) configuring the processor to calculate a third luminance value from said at least one image frame acquired in sub-step d1);

d3) configuring the processor to compare the third luminance value with a third predetermined threshold value; and

d4) configuring the processor to determine that the object is detected in said at least one image frame acquired in sub-step d1) when the third luminance value is smaller than the predetermined third threshold value.

15. A motion recognition device comprising:

a lighting unit having at least one lighting module for providing a light source at an illumination area;

an image acquiring unit including a photodetector array and an analog-to-digital converter (ADC), said photodetector array including a plurality of photodetectors arranged on a two-dimensional plane and being operable to generate sense signals by detecting intensity of light received thereby, said photodetector array having a detection area, at least a part of which overlaps the illumination area of said at least one lighting module, said ADC being coupled to said photodetector array for receiving the sense signals therefrom and being operable to convert the sense signals into image frames; and

a processor coupled to said ADC of said image acquiring unit and co-operable with said image acquiring unit to implement a method as claimed in claim 13 for determining whether an object is detected in at least one of the image frames and, when the determination is affirmative, determining a motion of the object with respect to a three-dimensional coordinate system according to a part of the image frames that are acquired after acquisition of said at least one of the image frames where the object is detected.