Endoscopic camera region of interest autoexposure

Abstract

An endoscopic camera system having a camera that captures and outputs an image; a camera controller coupled to the camera; a user input device coupled to the camera or the camera controller, wherein the user input device is usable to select a region of interest in the image, the region of interest being a sub-part of the image; and wherein the camera controller: computes a measured luminance value for the region of interest; and adjusts an exposure in response to a comparison of the measured luminance value with a target luminance value

What is claimed is: 
     
         1 . An endoscopic camera system comprising:
 a camera that captures and outputs an image;   a camera controller coupled to the camera; and   a user input device coupled to the camera or the camera controller, wherein the user input device is usable to select a region of interest in the image, the region of interest being a sub-part of the image;   wherein the camera controller:   computes a measured luminance value for the region of interest; and   adjusts an exposure in response to a comparison of the measured luminance value with a target luminance value.   
     
     
         2 . The system of  claim 1 , wherein the luminance value is a weighted sum of at least one of:
 an average green intensity, an average red intensity, and an average blue intensity in the region of the interest.   
     
     
         3 . The system of  claim 1 , wherein the luminance value is a weighted sum of an average green intensity in the region of the interest. 
     
     
         4 . The system of  claim 1 , wherein adjusting the exposure further comprises adjusting at least one of an exposure time, a light source intensity, a gain, a sensitivity, and a variable aperture. 
     
     
         5 . The system of  claim 1 , wherein the camera has a longitudinal axis and captures the image at a non-zero angle to the longitudinal axis. 
     
     
         6 . The system of  claim 5  wherein the camera captures the image at a capture angle of about 45 degrees relative to the longitudinal axis. 
     
     
         7 . The system of  claim 5  wherein the user input device is usable to select a region of interest having an apparent capture angle that is different than the actual capture angle. The system of  claim 7  wherein the user input device is usable to select a region of interest having an apparent capture angle at least one of: 30 degrees, 45 degrees and 70 degrees. 
     
     
         9 . The system of  claim 1  wherein the camera captures and outputs an image having a field of view greater than about 90 degrees. 
     
     
         10 . The system of  claim 9  wherein the user input device is usable to select a region of interest having an apparent field of view that is smaller than the image field of view. 
     
     
         11 . The system of  claim 1  wherein the camera captures and outputs an image having a field of view greater than about  140  degrees. 
     
     
         12 . A method of adjusting an exposure for an imaging system, comprising:
 receiving an image from a camera;   receiving a region of interest in the image from a user, the region of interest being a sub-part of the image;   computing a measured luminance value for the region of interest; and   adjusting an exposure in response to a comparison of the measured luminance value with a target luminance value.   
     
     
         13 . The method of  claim 12 , wherein computing the measured luminance value further comprises computing a weighted sum of an average green intensity, an average red intensity, and an average blue intensity in the region of the interest. 
     
     
         14 . The method of  claim 12 , wherein computing the measured luminance value further comprises computing a weighted sum of an average green intensity in the region of interest. 
     
     
         15 . The method of  claim 12  wherein adjusting the exposure further comprises adjusting at least one of an exposure time, a light source intensity, a gain, a sensitivity, and a variable aperture. 
     
     
         16 . The method of  claim 12 , wherein the image is captured at an actual capture angle greater than zero relative to a longitudinal axis and wherein the received region of interest has an apparent capture angle that is different than the actual capture angle. 
     
     
         17 . The method of  claim 12  wherein the image has a field of view greater than about 90 degrees and wherein the received region of interest has an apparent field of view that is less than the image field of view. 
     
     
         18 . The method of  claim 12  wherein the image has a field of view greater than about 140 degrees and wherein the received region of interest has an apparent field of view that is less than the image field of view.