Contrast invariant registration of images

We propose a method for image registration which seems to be useful under the three following conditions. First, both images are globally and roughly the result of a translation and rotation. Second, some occlusions due to moving objects occur from image 1 to image 2. Third, because of changes of illumination, contrast may have changed globally and even locally. Under such unfavorable conditions, correlation-based global registration may become inaccurate, because of the global compromise it yields between several displacements. Our method avoids these difficulties by defining a set of local contrast invariant features in order to achieve contrast invariant matching. A voting procedure allows one to eliminate "wrong" matching features due to the displacement of small objects and yields sub-pixel accuracy. This method was tested successfully for registration of watches with moving hands and for road control applications.