Image processing device and method of operating same

A method of operating an image processing device including an image processor, the method comprising:

• acquiring an endoscopic image obtained by imaging a subject with an endoscope;
• calculating biological information on the basis of the endoscopic image;
• setting a reference value of the biological information;
• generating a biological information image obtained by forming the biological information as an image so that a low value region equal to or lower than the reference value and the other region are distinguishable from each other;
• generating a display image in which the biological information image is superimposed on the endoscopic image;
• determining that the reference value is not appropriate in a case where a quasi-low value region in which the biological information is higher than the reference value and equal to or lower than a preset set value is present in the biological information image;
• and
• performing a notification regarding the reference value in a case where it is determined the reference value is not appropriate.