The disclosure concerns processing of electronic images, such as hyperspectral or multispectral images. Processing of the images includes object recognition and image enhancement in a way that harnesses the information available from the image based on the wavelength indexed spectral data these types of images provide. Illumination spectrum of such an image is estimated (FIG. 21) using a cost function based on a dichromatic reflection model and a constraint term. This method may be performed on sub-images of the image. A method for selecting these sub-images (FIG. 23) is also disclosed. A method of determining photometric parameters of the image given the estimated illumination spectrum (FIG. 22) is also disclosed.