Image processing device, image processing method, and computer program product for adjusting white balance of an image captured by an imaging device

An image processing device according to the present disclosure includes a memory in which a program is stored; and a processor coupled to the memory and configured to perform processing by executing the program. The processing includes: acquiring, from an imaging device mounted inside a cabin of a vehicle, an image of an outside of the cabin captured through a window of the vehicle by the imaging device; acquiring a color temperature from the acquired image; detecting a color temperature range regarded as white by the imaging device from the acquired color temperature; adjusting white balance of the image based on the detected color temperature range; and outputting the image of which the white balance is adjusted.