Improved Illumination Correction that Preserves Medium Sized Objects

Illumination correction is a method used for removing the influence of light coming from the environment and of other distorting factors in the image capturing process. An algorithm based on the luminance mapping is proposed that can be used to remove low frequency variations in the intensity, and to increase the contrast in low contrast areas when necessary. Moreover, the algorithm can be employed to preserve the intensity of medium-sized objects with different intensity or colour than their surroundings, which otherwise would tend to be washed out. Furthermore, examples are given showing how the method can be used for both greyscale images and colour photos.