Contrast Invariant Image Registration

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 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.