Patent ID: 7652251
Filing Date: 2010-01-26
Classification: G02B,G03B,H04N

Abstract:
1. A method employed by a thermal imaging apparatus, the method for registering infrared images with visible light images, each of the infrared images being captured, by an infrared sensor of the imaging apparatus, in a corresponding infrared field of view, which is defined by an array of infrared pixels, the infrared sensor being aligned, along a first axis, with a first lens of the imaging apparatus, each of the corresponding visible light images being captured, by a visible light sensor of the imaging apparatus, in a corresponding visible field of view, which is defined by an array of visible pixels, the visible light sensor being aligned, along a second axis, with a second lens of the imaging apparatus, and the method comprising: capturing an infrared image of the object in an infrared field of view, the first lens of the imaging apparatus having been focused on the object which object is located at a distance from the first lens; capturing a visible light image of the object, at the distance, in a visible field of view; determining a reference height and a reference width of the infrared field of view, the reference height and the reference width being defined in terms of visible pixels in the visible field of view; determining the distance from the focused first lens to the object; multiplying each of the reference height and the reference width of the infrared field of view by a magnification correction factor in order to obtain a corrected height and a corrected width of the infrared field of view, the magnification correction factor being a function of a focal length of the first lens, the determined distance, and a reference distance, at which reference distance the magnification correction factor is equal to one; and calculating coordinates, in terms of visible pixels, for a center of the infrared field of view within the array of visible pixels of the visible field of view, in order to register the infrared image of the object with the visible light image of the object.