Endoscope system and method of operating the same

A method of operating an endoscope system that illuminates a subject and images light from the subject, and that includes an endoscope including a zoom lens and a lens driving processor for driving the zoom lens, and a processor device including an image acquisition processor, the method comprising:

• a step of driving the zoom lens, executed by the lens driving processor, in accordance with pressing of a freeze button;
• and
• following steps, executed by the image acquisition processor, of:
• acquiring examination images which are time-sequentially continuous images before the freeze button is pressed;
• acquiring the examination images in conjunction with movement of the zoom lens driven by the lens driving processor during a post-press evaluation time which is a time after the pressing of the freeze button in a total evaluation time which is a certain time before and after the pressing of the freeze button;
• calculating evaluation values of the examination images selected as post-press evaluation frame images from the examination images acquired within the post-press evaluation time;
• selecting the post-press evaluation frame image having a highest evaluation value among the post-press evaluation frame images for which the evaluation values have been calculated, as an optimal image;
• and
• displaying the optimal image,
• wherein the image acquisition processor further executes steps of:
• storing the examination images for evaluation holding frames as evaluation holding frame images from the examination images acquired during the total evaluation time;
• and
• calculating the evaluation values of the stored evaluation holding frame images,
• wherein the total evaluation time is a combined time of the post-press evaluation time and a pre-press evaluation time which is a time before the pressing of the freeze button,
• the evaluation holding frame image consists of the post-press evaluation frame image and a pre-press evaluation frame image including the examination image acquired during the pre-press evaluation time, and
• the image acquisition processor further executes a step of calculating the evaluation values of the post-press evaluation frame image and the pre-press evaluation frame image, and
• wherein the image acquisition processor further executes a step of, within a range of the evaluation holding frames, storing the examination images except for some frames as the pre-press evaluation frame images in the pre-press evaluation time and storing the examination images of all frames as the post-press evaluation frame images in the post-press evaluation time.