Underexposed Image Correction Via Approximation of the Scene Radiance Function

In this paper, we describe a method for correcting underexposed images by recovering the Lambertian diffuse component in the scene. The method makes use of an implicit mapping between the objects in the scene and a unit sphere. As a result of this treatment, the scene radiance function can be represented by a polar function on the unit sphere. We pose the problem of recovering the scene radiance function as that of estimating a tabular representation of this polar function. We demonstrate how image gradient information can be used to perform the required mapping. With the mapping at hand, we generate an image corresponding to the diffuse component of the scene. The diffuse and input images are then blended in order to obtain the corrected image. We present results on images of real-world scenes and provide comparison with an alternative.