Estimation of Image Magnification Using Phase Correlation

A new method to determine the magnification change between near and far focused images is presented. For a non-central image sub-block, the magnification can be determined by considering the translation of the block. In practice the central sub-block was used to measure the overall translation and non-central sub-blocks provide a map of magnification at different points within an image. The method employs Phase Correlation. Experimental results with simulated and real images show the method works effectively even for defocused images.