Ambient image recovery and rendering from flash photographs

It is challenging to capture good photographs in a low-light environment. Flash is often applied to increase the illumination, but flash ruins the natural ambient lighting and makes the scene look flat. Solutions without using flash include prolonging exposure time, enlarging the aperture or using high ISO film (or the equivalent setting for digital cameras). These brighten the image at the expense of image quality. In this paper, we present a method to avoids such problems. Our technique combines multiple photographs, taken under varying flash intensities, to recover the intrinsic ambient scene radiance. From this, we can re-render the scene under an arbitrary shutter speed to create a visually pleasant image. We can also simulate the effects of different white-balance settings, as well as different flash intensities. Experiments show that our method can produce high quality images compared to traditional non-flash solutions.