Endoscope system, processor device thereof, and image producing method

A processor for an endoscope system, the endoscope system comprising a lighting device and an endoscope device, the lighting device applying at least first and second illumination light, in respective frames, to a region of interest including a blood vessel, a wavelength range of the first illumination light being different from a wavelength range of the second illumination light, the endoscope device imaging the region of interest in the each frame with a color image sensor having an array of pixels of at least three primary colors, the endoscope device imaging the region of interest illuminated with the first illumination light to acquire a blue signal, a green signal and a red signal of a first frame, the endoscope device imaging the region of interest illuminated with the second illumination light to acquire a blue signal, a green signal and a red signal of a second frame,

• the processor, executing computer executable instructions stored in a non-transitory computer readable medium, configured to perform functions of:
• receiving the color signals of each of the first and second frames from the endoscope device;
• calculating a shift amount between an image of the first frame and an image of the second frame based on the signals of the same color;
• aligning images of the blue signal of the first frame and the green and red signals of the second frame, used for calculating an oxygen saturation level of hemoglobin in blood, based on the shift amount;
• and
• producing an oxygen saturation image of the oxygen saturation level based on only the blue signal of the first frame, and the green and red signals of the second frame that are aligned.

An image producing method comprising the steps of:

• applying at least first illumination light and second illumination light having different wavelength ranges, in respective frames, to a region of interest including a blood vessel, and imaging the region of interest in the each frame with a color image sensor having an array of pixels of at least three primary colors, the color image sensor imaging the region of interest illuminated with the first illumination light to acquire a blue signal, a green signal and a red signal of a first frame, the color image sensor imaging the region of interest illuminated with the second illumination light to acquire a blue signal, a green signal and a red signal of a second frame;
• calculating a shift amount between an image of the first frame and an image of the second frame based on the color signals of same color;
• aligning images of the blue signal of the first frame and the green and red signals of the second frame, used for calculating an oxygen saturation level of hemoglobin in blood, based on the shift amount;
• and
• producing an oxygen saturation image of the oxygen saturation level based on only the blue signal of the first frame, and the green and red signals of the second frame that are aligned.