USING IMAGE REGISTRATION AND ALIGNMENT TO COMPARE ALTERNATIVE 2D MEASUREMENTS

We present in this paper a novel method for comparing alternative 2D measurements. The method is based on a new image registration algorithm developed for the automatic registration and alignment of randomly textured image data. Our aim in the algorithm development has been to enable fast registration of the measured 2D property maps without the need for special registration marks. To improve robustness, the maps are registered in two steps; the first step exhibits plain translation and the second phase iteratively refines the transformation estimate. Sub-pixel registration accuracy is achieved. Several experiments have been conducted showing that the algorithm is able to register various 2D property maps successfully. After the registration we align the alternative 2D measurements. This enables the comparison and statistical joint analysis of several 2D property maps measured from the same target area. The high amount of independently measured data points in the property maps provides a firm statistical ground for conclusions. We have used the new registration algorithm to align various 2D surface profile measurements of paper and board. The analysis of the aligned measurements has confirmed the feasibility of our registration method and revealed fundamental differences between the measurement devices.