Flame detection system and method
View Patent ↗A hazard detection system measures a color and intensity of a portion of an image of a scene. The image is obtained using a known gain and/or exposure such that the image substantially lacks any saturation. A black body brightness temperature and the corresponding block body intensity are determined based on the measured color. A hazard condition, such the presence of a flame, can be detected using a comparison of the measured intensity and the computed intensity. The gain and/or exposure can be selected such that only the pixels of intensity greater than a certain threshold generally saturate in the captured image. Hazard conditions, such as smoke, can be detected using images in which selective saturation is permitted.
1. A method of detecting a hazard, the method comprising:
obtaining a first image of a scene;
measuring color and intensity of at least a portion of the first image, using a value of at least one imaging parameter associated with the first image;
computing a reference intensity related to the measured color; and
comparing the measured intensity with the reference intensity to determine at least in part if the portion of the first image indicates a hazard condition by computing an emissivity factor as a ratio of the measured intensity to the reference intensity; and determining if the emissivity factor lies within a specified range corresponding to the hazard condition.
2. The method of claim 1 , wherein the obtaining step comprises receiving the first image from an imaging device.
3. The method of claim 1 , wherein the obtaining step comprises: adjusting the at least one imaging parameter of an image sensing device to remove saturation in an image captured by the device; and capturing an image of the scene via the device to obtain the first image.
4. The method of claim 3 , wherein the at least one imaging parameter comprises at least one of a gain, an exposure, and an aperture of an imaging device.
5. The method of claim 3 , wherein the at least one imaging parameter comprises a substantially constant gain.
6. The method of claim 1 , wherein the at least one imaging parameter comprises at least one of a gain, an exposure, and an aperture of an imaging device.
7. The method of claim 1 , wherein the computing step comprises: determining a black body brightness temperature corresponding to the measured color; and computing the reference intensity based at least in part on the black body brightness temperature.
8. The method of claim 1 , wherein the hazard condition comprises a flame.
9. The method of claim 1 , further comprising: obtaining a second image of the scene; and repeating the measuring, computing, and comparing steps for at least a portion of the second image that corresponds to the at least a portion of the first image.
10. The method of claim 1 , further comprising determining if the measured color corresponds to a black body color to determine at least in part if the portion of the first image indicates a hazard condition.
11. The method of claim 1 , further comprising: obtaining a second image of the scene; and correlating the first image and the second image to determine a location of the hazard.
12. A hazard detection system comprising:
an imaging device comprising a parameter selectable to remove saturation in a first image of a scene captured by the imaging device; and
a processor adapted to:
measure color and intensity of at least a portion of the captured first image;
compute a reference intensity related to the measured color; and
compare the measured intensity with the reference intensity to determine at least in part if the portion of the captured first image indicates a hazard condition,
wherein the imaging device is further adapted to capture a second image of the scene, the parameter being selected to allow saturation in the second image; and the processor is further adapted to spatially correlate the first and second images, to determine a location of any detected hazard.
13. The system of claim 12 , wherein the imaging device comprises a CMOS image sensor adapted to capture images at a rate of at least 30 frames per second.
14. The system of claim 12 , wherein the parameter comprises at least one of gain, exposure, and aperture.
15. The system of claim 12 , wherein the parameter comprises a substantially constant gain.