1. An image processing device comprising: a detecting unit configured to detect an external light reflection region from an input image; a determining unit configured to determine a glossiness of said external light reflection region; an extracting unit configured to extract a gloss region based on the determination result of said glossiness; and a gloss control unit configured to transmit a control signal to a transparent plate, the control signal controlling an external light reflection of the transparent plate based on the extracted gloss region.