Thermal camera health monitoring

Patent metadata

Field	Value
Publication number	US-11343447-B2
Application number	US-202017109520-A
Country	US
Kind code	B2
Filing date	Dec 2, 2020
Priority date	Dec 5, 2019
Publication date	May 24, 2022
Grant date	May 24, 2022

Abstract

Methods and apparatus, including computer program products, for detecting a problem with a thermal camera. A current contrast value is determined for the thermal camera. It is determined whether the current contrast value deviates from a reference contrast value by more than a predetermined value. In response to determining that the current contrast value deviates from the reference contrast value by more than a predetermined value and for more than a predetermined period of time, an indication of a problem with the thermal camera is provided.

First claim

What is claimed is:

1. A method for detecting a problem with a thermal camera, comprising:
determining a current contrast value for the thermal camera;
determining whether the current contrast value deviates from a reference contrast value by more than a predetermined value;
in response to determining that the current contrast value deviates from the reference contrast value by more than a predetermined value, starting a timer; and
in response to determining that the current contrast value deviates from the reference contrast value by more than a predetermined value and for more than a predetermined period of time since the timer was started, providing an indication of a problem with the thermal camera.

2. The method of claim 1 , wherein the problem is one of: the thermal camera having been tampered with, the thermal camera having been redirected, and the lens of the thermal camera being affected in a way that causes transmission loss.

3. The method of claim 1 , wherein the reference contrast value and the current contrast value are determined using one of: a contrast value representative of a Sobel image obtained by applying a Sobel algorithm to an image captured by the thermal camera, a Michelson contrast algorithm applied to the image captured by the thermal camera, and an image entropy algorithm applied to the image captured by the thermal camera.

4. The method of claim 1 , wherein the predetermined value is based on a Johnson criterion pertaining to one or more of: detection, recognition and identification of an object having a temperature that differs from the temperature of a homogenous background by at least 2° C., and wherein at least 1.5 pixels are used for detection of the object, at least 6 pixels are used for recognition of the object and at least 12 pixels are used for identification of the object.

5. The method of claim 1 , wherein the reference contrast value is generated through applying a machine learning process on measured contrast values over a period of time.

6. The method of claim 1 , wherein providing an indication of a problem further comprises:
starting a timer in response to an earliest determination that the current contrast value deviates from the reference contrast value by more than the predetermined value;
at regular time intervals, repeating the determination of a current contrast value and the determination of whether the current contrast value deviates from the reference contrast value; and
in response to detecting that the current contrast values remain deviant from the reference contrast value by more than the predetermined value and for more than a predetermined period since the timer was started, providing the indication of a problem related to the thermal camera.

7. The method of claim 6 , wherein the regular time intervals range from approximately one to three days.

8. A system for detecting a problem with a thermal camera, comprising:
a memory; and
a processor,
wherein the memory contains instructions that when executed by the processor causes the processor to perform a method that includes:
determining a current contrast value for the thermal camera;
determining whether the current contrast value deviates from a reference contrast value by more than a predetermined value;
in response to determining that the current contrast value deviates from the reference contrast value by more than a predetermined value, starting a timer; and
in response to determining that the current contrast value deviates from the reference contrast value by more than a predetermined value and for more than a predetermined period of time since the timer was started, providing an indication of a problem with the thermal camera.

9. A thermal camera including a system as described in claim 8 .

10. A non-transitory computer readable storage medium having program instructions embodied therewith, the program instructions being executable by a processor to perform a method for detecting a problem with a thermal camera, the comprising method comprising:
determining a current contrast value for the thermal camera;
determining whether the current contrast value deviates from a reference contrast value by more than a predetermined value;
in response to determining that the current contrast value deviates from the reference contrast value by more than a predetermined value, starting a timer; and
in response to determining that the current contrast value deviates from the reference contrast value by more than a predetermined value and for more than a predetermined period of time since the timer was started, providing an indication of a problem with the thermal camera.

Assignees

• Axis Ab

Inventors

• Winzell Thomas
• Bengtsson Jesper
• Bylander Mats

Classifications

• G06V10/10 Primary

  Image acquisition (document image scanning and transmission H04N1/00; control of digital cameras H04N23/60) · CPC title

• H04N23/23

  from thermal infrared radiation · CPC title

• H04N7/18

  Closed-circuit television [CCTV] systems, i.e. systems in which the video signal is not broadcast · CPC title

• G06N20/00

  Machine learning · CPC title

• G01J2005/0077

  Imaging · CPC title