Image processing apparatus, endoscope apparatus and color balance adjusting method

An endoscope apparatus comprising:

• a color balance adjusting tool including:
• a fluorescent light generating portion for emitting fluorescent light when radiated with excitation light;
• and
• an intensity variation correction value display portion for displaying an intensity variation correction value for correcting variation in intensity of fluorescent light emitted from the fluorescent light generating portion;
• an endoscope including an image pickup unit for:
• picking up a fluorescent light image when the excitation light is radiated to the color balance adjustment tool,
• picking up a reflection light image generated when a light in a wavelength band different from that of the excitation light is radiated to the color balance adjustment tool, and
• outputting the picked-up fluorescent light image and the picked-up reflection light image as an image signal;
• and
• an image processing apparatus for:
• calculating a coefficient value for changing a brightness value of the image signal based on a brightness value of the fluorescent light image, a brightness value of the reflection light image, and the intensity variation correction value, and
• performing color balance adjustment by changing the brightness value of the image signal using the coefficient value,
• wherein the image processing apparatus calculates the coefficient value using the mathematical expression:
• WBKR=WBAF/(WBR×WBCAF)
• with WBKR being the coefficient value, WBAF being the brightness value of the fluorescent light image, WBR being the brightness value of the reflection light image, and WBCAF being the intensity variation correction value.

A color balance adjusting method comprising:

• an image signal input step for inputting an image signal that includes:
• a fluorescent light subject image picked up by an image pickup unit when an excitation light is radiated to, the subject image including at least an image of a color balance adjustment tool that includes a fluorescent light generating portion and an intensity variation correction value display portion for displaying an intensity variation correction value for correcting variation in intensity of fluorescent light emitted from the fluorescent light generating portion;
• and
• a reflection light image picked up by the image pickup unit when a light in a wavelength band different from that of the excitation light is radiated to the color balance adjustment tool;
• an intensity variation correction value input judgment step for judging whether or not the intensity variation correction value has been input;
• a brightness value calculation step for calculating, based on the image signal, a mean value of brightness values in an image including one wavelength band of the fluorescent light image and a mean value of brightness values of the reflection light image, when it is judged that the intensity variation correction value has been inputted in the intensity variation correction value input judgment step;
• a coefficient value calculation step for calculating a coefficient value to be used for color balance adjustment of the image signal, based on the intensity variation correction value and each of the mean values calculated in the brightness value calculation step;
• and
• a color balance adjustment step for changing the brightness value of the image signal using the coefficient value,
• wherein in the coefficient value calculation step, the coefficient value is calculated using the mathematical expression:
• WBKR=WBAF/(WBR×WBCAF)
• with WBKR being the coefficient value, WBAF being the brightness value of the fluorescent light image, WBR being the brightness value of the reflection light image, and WBCAF being the intensity variation correction value.