An automated process empirically normalizes a “dark” image by adjusting the apparent exposure to compensate for nonlinearity in the luminance response of the image sensor. The process includes receiving at least two digital images, one of the digital images having an exposure value that is greater than that of another of the digital images. A reduced-resolution pair of images is produced from the at least two digital images. At least one representative scale factor is calculated from tonal values in the two images and at least one empirical scale factor is determined by selective interpolation between the representative scale factor and a comparative scale factor. The empirical scale factor is used in a function applied pixelwise to the darker of the digital images to produce an empirically normalized digital image.