Endoscope apparatus and operating method of endoscope apparatus

An operating method of an endoscope apparatus comprising:

• controlling a focus position of an objective optical system, the objective optical system being configured to form an image of reflected light from a subject on an image sensor, the subject reflecting illumination light emitted thereon, such that focus positions at timings when respective images in N frames are sequentially captured by the image sensor differ from each other, N being an integer of two or more;
• controlling a quantity of light emission of the illumination light such that quantities of light emission of the illumination light when the respective images in N frames are captured become equal to each other, or performing a correction process of at least one of the respective images such that brightness of the respective images in N frames becomes equal to each other;
• and
• after controlling the focus position and controlling the quantities of light emission or performing the correction process, combining the respective images in N frames, each having different focused parts, into a depth of field extended image in one frame by coupling the focused parts with each other.

An endoscope system comprising:

• an endoscope comprising an image sensor;
• and
• an endoscope apparatus comprising:
• a processor configured to:
• control a focus position of an objective optical system;
• acquire images sequentially captured by the image sensor;
• combine the images in N frames (N is an integer of two or more) each having different focused parts thus acquired into a depth of field extended image in one frame, by coupling the focused parts with each other;
• and
• control the illumination light before combination into the depth of field extended image in one frame;
• control the focus position such that focus positions at timings when the respective images in N frames are captured differ from each other;
• combine images in a first set of N frames into a first depth of field extended image and images in a second set of N frames captured after the images in the first set of N frames into a second depth of field extended image;
• and
• change a quantity of light emission of the illumination light in a period between a period when the images in the first set of N frames are captured and a period when the images in the second set of N frames are captured, or
• perform, before combination into the depth of field extended image in one frame, a correcting process of at least one of the respective images to equalize brightness of the respective images in N frames.