Methods are disclosed for tonally balancing multiple images. In one
embodiment, the method comprises using a subset of corresponding points
in each of a plurality of image overlap regions to solve a set of
minimization equations for gains and biases for each spectral band of
each image, the corresponding points being points from different images
having locations that correspond to each other, the subset of
corresponding points consisting of corresponding points whose intensities
differ less than a threshold, applying the gains and biases to the
images, and iterating said using and applying actions for a predetermined
number of iterations.