Endoscope apparatus and control method of endoscope apparatus

A control method for an endoscope apparatus, comprising:

• a region dividing step in which a region dividing portion divides an endoscope image into a center region and a peripheral region;
• a peripheral brightness mean value calculation step in which a peripheral brightness mean value calculation portion calculates a peripheral brightness mean value that indicates a mean value of a brightness of the peripheral region;
• a center brightness mean value calculation step in which a center brightness mean value calculation portion calculates a center brightness mean value that indicates a mean value of a brightness of the center region;
• a first weighting factor calculation step in which a weighting factor calculation portion calculates a first weighting factor α (where 0<α<1) based on a ratio between the center brightness mean value and the peripheral brightness mean value;
• a first photometric value calculation step in which a first photometric value calculation portion calculates a first photometric value based on a sum total of a value obtained by multiplying the center brightness mean value by the first weighting factor α and a value obtained by multiplying the peripheral brightness mean value by (1−α);
• and
• a brightness adjustment control step in which a brightness adjustment control portion generates a brightness adjustment control signal that adjusts a brightness of the endoscope image based on the first photometric value;
• wherein, in the weighting factor calculation step, when the ratio between the peripheral brightness mean value and the center brightness mean value is in a predetermined range that is centered around a value of 1, even if the ratio changes, the weighting factor calculation portion calculates the first weighting factor α of a same value.