Patent ID: 7283666

Claim:
A method for correcting the exposure of a source image, the method comprising steps of: (A) transforming the source image from an image capture space into a nonlinear intensity space to produce a first transformed image; (B) correcting the exposure of the transformed image in the nonlinear intensity space to produce a corrected transformed image; and (C) transforming the corrected transformed image back into the image capture space to produce a second transformed image by steps comprising: (C)(1) transforming the corrected transformed image into a third transformed image using an S-shaped curve; and (C)(2) transforming the third transformed image into the second transformed image using a gamma functions; wherein the step (C) comprises a step of transforming the corrected transformed image into the second transformed image using the formula: T ( i )=( A+B tan h (−s( +o ))) 1/γ wherein i represents an intensity in the nonlinear intensity space, wherein A, B. s and o are parameters of said S-shaped curve and wherein γ is a gamma value of an output device for rendering the corrected transformed image.