An image processing apparatus includes: a reduced image generation unit configured to obtain a reduced image; a gain data generation unit configured to obtain gain data; and a determination unit configured to determine a control gain required to amplify the input image based on the generated gain data, and letting first gain data be the gain data for an image having a relatively high frequency, and second gain data be the gain data having a relatively low frequency, the determination unit determines the control gain based on a first addition result and a second addition result.