Camera control apparatus, control method, and non-transitory computer readable medium

A control method comprising:

• determining a part of a first image including an authentication target as a first area, the first image being obtained by capturing a nearby environment;
• determining a part of a second image including the authentication target as a second area, the second image being obtained by setting a control parameter of a camera control apparatus so that a state of an image of the authentication target becomes an optimum state for authentication of the authentication target and then capturing the nearby environment;
• determining a part of a third image including the authentication target as a third area, the third image being obtained by capturing the nearby environment before the first image is captured;
• calculating a first state difference, the first state difference being a difference between a second state indicating a state of the image of the second area and a first state indicating a state of the image of the first area;
• calculating a second state difference, the second state difference being a difference between a third state indicating a state of the image of the third area and the first state;
• and
• determining the control parameter so that a sum of the first state difference and the second state difference falls within a predetermined state difference range based on the first state difference and the second state difference.

A non-transitory computer readable medium storing a program for causing a computer to:

• determine a part of a first image including an authentication target as a first area, the first image being obtained by capturing a nearby environment;
• determine a part of a second image including the authentication target as a second area, the second image being obtained by setting a control parameter of a camera control apparatus so that a state of an image of the authentication target becomes an optimum state for authentication of the authentication target and then capturing the nearby environment;
• determine a part of a third image including the authentication target as a third area, the third image being obtained by capturing the nearby environment before the first image is captured;
• calculate a first state difference, the first state difference being a difference between a second state indicating a state of the image of the second area and a first state indicating a state of the image of the first area;
• calculate a second state difference, the second state difference being a difference between a third state indicating a state of the image of the third area and the first state;
• and
• determine the control parameter so that a sum of the first state difference and the second state difference falls within a predetermined state difference range based on the first state difference and the second state difference.