Evaluation value calculation device and electronic endoscope system

Abstract

An electronic endoscope system includes a plotting unit which plots pixel correspondence points, which correspond to pixels that constitute an intracavitary color image that has a plurality of color components, on a target plane according to color components of the pixel correspondence points, the target plane intersecting the origin of a predetermined color space; an axis setting unit which sets a reference axis in the target plane based on pixel correspondence points plotted on the target plane; and an evaluation value calculating unit which calculates a prescribed evaluation value with respect to the captured image based on a positional relationship between the reference axis and the pixel correspondence points.

What is claimed is: 
     
         1 . An evaluation value calculation device comprising:
 an image capturing unit configured to capture a color image that has R (Red), G (Green), and B (Blue) color components;   a plotting unit configured to plot pixel correspondence points, which correspond to pixels that constitute a captured image obtained by the image capturing unit, on a target plane according to color components of the pixel correspondence points, the target plane including a first axis that is an R component axis and a second axis that is a G component axis and is orthogonal to the first axis;   an axis setting unit configured to set a reference axis that passes through an intersection of the first axis and the second axis in the target plane and is not parallel with each of the first axis and the second axis, based on pixel correspondence points plotted on the target plane; and   an evaluation value calculating unit configured to calculate a prescribed evaluation value with respect to the captured image based on a positional relationship between the reference axis and the pixel correspondence points.   
     
     
         2 . The evaluation value calculation device according to  claim 1 , wherein:
 a start point of the first axis and a start point of the second axis are at the same location,   the axis setting unit detects a pixel correspondence point that is located on a line segment connecting an end point of the second axis and an end point of the first axis and that is closest to the end point of the second axis, and sets an axis that connects the detected pixel correspondence point and the start point as the reference axis.   
     
     
         3 . The evaluation value calculation device according to  claim 1 , wherein the axis setting unit sets the reference axis each time the captured image is captured by the image capturing unit, or only at a predetermined timing. 
     
     
         4 . The evaluation value calculation device according to  claim 1 , wherein the axis setting unit calculates a provisional reference axis each time a predetermined timing is reached, and sets the reference axis based on the provisional reference axes calculated at the timings. 
     
     
         5 . The evaluation value calculation device according to  claim 1 ,
 wherein the reference axis is an axis having a high correlation with a hue of a mucous membrane in a body cavity.   
     
     
         6 . The evaluation value calculation device according to  claim 1 , wherein the prescribed evaluation value is a numerical representation of an abnormal portion in a body cavity. 
     
     
         7 . The evaluation value calculation device according to  claim 1 , wherein the evaluation value calculation device is for incorporation in an electronic endoscope system. 
     
     
         8 . The evaluation value calculation device according to  claim 1 , wherein the reference axis is an axis drawn on a boundary line between a region in which the pixel correspondence points are distributed and a region in which pixel correspondence points are not distributed in the target plane.