Image capturing method and monitoring apparatus with supplemental lighting modulation

• US 10,057,500 B2
• Filed: 09/08/2017
• Issued: 08/21/2018
• Est. Priority Date: 09/19/2016
• Status: Active Grant

• Current Assignee: Vivotek, Inc.
• Original Assignee: Vivotek, Inc.
• Inventors: Shih, Li-Shan, Chen, Yi-Chuan
• Primary Examiner(s): Nazrul, Shahbaz
• Application Number:
  US15/698,658
• Publication Number:
  US 20180084179A1
• Time in Patent Office: 347 Days
• CPC Class Codes: G06V 10/141 Control of illumination
• CPC Class Codes: G06V 20/54 of traffic, e.g. cars on the road, trains or boats
• CPC Class Codes: G06V 20/625 License plates
• CPC Class Codes: G06V 20/63 Scene text, e.g. street names
• CPC Class Codes: H04N 23/10 for generating image signals from different wavelengths
• CPC Class Codes: H04N 23/74 by influencing the scene brightness using illuminating means
• CPC Class Codes: H04N 5/144 Movement detection for video coding H04N19/503; analysis of motion in general G06T7/20

Abstract

An image capturing method with supplemental lighting modulation is applied to a monitoring apparatus having a lighting unit and an image detecting unit. The image capturing method includes dividing a working period of the lighting unit into at least one first sub-period and at least one second sub-period, driving the lighting unit to respectively output supplemental light with different intensity during the first sub-period and the second sub-period, driving the image detecting unit to respectively capture a set of monitoring images with a predetermined amount during the first sub-period and the second sub-period, comparing the monitoring image captured in the first sub-period with ones captured in the second sub-period, analyzing definition of the set of monitoring images, and selecting a corresponding monitoring image having the definition greater than a threshold to execute image recognition.

Claims

1. An image capturing method with supplemental lighting modulation, applied to a monitoring apparatus having a lighting unit and an image detecting unit, the image capturing method comprising:

dividing a working period of the lighting unit into at least one first sub-period and at least one second sub-period;

driving the lighting unit to respectively emit supplemental light with different intensity during the first sub-period and the second sub-period;

driving the image detecting unit to respectively capture a set of monitoring images with a predetermined amount during the first sub-period and the second sub-period;

comparing the monitoring image captured in the first sub-period with ones captured in the second sub-period; and

analyzing definition of the set of monitoring images and selecting one of the monitoring images having the definition greater than a threshold to execute image recognition.

2. The image capturing method of claim 1, wherein the monitoring apparatus is utilized to detect a movement of an object within a monitoring region, the image capturing method further comprises:

setting a length of the working period according to a moving velocity of the object and a dimension of the monitoring region.

3. The image capturing method of claim 1, wherein a quantity of the set of monitoring images with the predetermined amount captured by the image detecting unit during at least one of the first sub-period and the second sub-period is adjusted according to a length of the working period.

4. The image capturing method of claim 1, wherein the monitoring apparatus is utilized to detect a movement of an object within a monitoring region, the image capturing method further comprises:

analyzing a reflectivity of the object; and

adjusting intensity of the supplemental light emitted from the lighting unit respectively during the first sub-period and the second sub-period according to the reflectivity.

5. The image capturing method of claim 1, further comprising:

adjusting intensity of the supplemental light emitted from the lighting unit respectively during the first sub-period and the second sub-period according to a comparison result between the definition and the threshold.

6. The image capturing method of claim 1, wherein the monitoring apparatus is utilized to detect a movement of an object within a monitoring region, the object is a vehicle, and the image recognition is applied to recognize a plate number of the vehicle.

7. The image capturing method of claim 1, further comprising:

forming a first image stream and a second image stream via the monitoring images captured by the image detecting unit respectively during the first sub-period and the second sub-period.

8. The image capturing method of claim 1, wherein the monitoring apparatus is utilized to execute the image capturing method while detecting a movement of an object within a monitoring region.

9. The image capturing method of claim 1, wherein intensity of the supplemental light emitted from the lighting unit respectively during the first sub-period and the second sub-period is steadied while the definition of the monitoring images are greater than the threshold.

10. The image capturing method of claim 9, further comprising:

computing a quantity of the monitoring images having the definition greater than the threshold; and

steadying intensity of the supplemental light emitted from the lighting unit respectively during the first sub-period and the second sub-period while the quantity is greater than a predetermined value.

11. A monitoring apparatus with supplemental lighting modulation, the monitoring apparatus comprises:

a lighting unit adapted to emit supplemental light having adjustable intensity; and

an image detecting unit electrically connected to the lighting unit, and adapted to divide a working period of the lighting unit into at least one first sub-period and at least one second sub-period, drive the lighting unit to respectively emit supplemental light with different intensity during the first sub-period and the second sub-period, drive the image detecting unit to respectively capture a set of monitoring images with a predetermined amount during the first sub-period and the second sub-period, compare the monitoring image captured in the first sub-period with ones captured in the second sub-period, and analyze definition of the set of monitoring images and selecting one of the monitoring images having the definition greater than a threshold to execute image recognition, so as to clearly recognize a plurality of objects respectively made by different reflective material.

12. The monitoring apparatus of claim 11, wherein the monitoring apparatus is utilized to detect a movement of an object within a monitoring region, the image detecting unit is further adapted to set a length of the working period according to a moving velocity of the object and a dimension of the monitoring region.

13. The monitoring apparatus of claim 11, wherein a quantity of the set of monitoring images with the predetermined amount captured by the image detecting unit during at least one of the first sub-period and the second sub-period is adjusted according to a length of the working period.

14. The monitoring apparatus of claim 11, wherein the monitoring apparatus is utilized to detect a movement of an object within a monitoring region, the image detecting unit is further adapted to analyze a reflectivity of the object, and to adjust intensity of the supplemental light emitted from the lighting unit respectively during the first sub-period and the second sub-period according to the reflectivity.

15. The monitoring apparatus of claim 11, wherein the image detecting unit is further adapted to adjust intensity of the supplemental light emitted from the lighting unit respectively during the first sub-period and the second sub-period according to a comparison result between the definition and the threshold.

16. The monitoring apparatus of claim 11, wherein the monitoring apparatus is utilized to detect a movement of an object within a monitoring region, the object is a vehicle, and the image recognition is applied to recognize a plate number of the vehicle.

17. The monitoring apparatus of claim 11, wherein the image detecting unit is further adapted to form a first image stream and a second image stream via the monitoring images captured by the image detecting unit respectively during the first sub-period and the second sub-period.

18. The monitoring apparatus of claim 11, wherein the monitoring apparatus is utilized to execute the image capturing method while detecting a movement of an object within a monitoring region.

19. The monitoring apparatus of claim 11, wherein intensity of the supplemental light emitted from the lighting unit respectively during the first sub-period and the second sub-period is steadied while the definition of the monitoring images are greater than the threshold.

20. The monitoring apparatus of claim 19, wherein the image detecting unit is further adapted to compute a quantity of the monitoring images having the definition greater than the threshold, and to steady intensity of the supplemental light emitted from the lighting unit respectively during the first sub-period and the second sub-period while the quantity is greater than a predetermined value.