1. An image generation system comprising: an image acquisition unit to acquire an image; an image generation unit to generate, from the acquired image, a first image with a first resolution and a first brightness and a second image with a second resolution and a predetermined second brightness, the second resolution being lower than the first resolution and the predetermined second brightness being greater than the first brightness; and an image synthesis unit to synthesize the generated images, wherein the second image is generated from the first image, such that the second resolution is determined based on a ratio of calculated exposure times and the first resolution.