Improved DCT-based Phase Correlation Method for Image Mosaicing

Abstract

This paper presents an image mosaicing technique based on an improved discrete cosine transform (DCT)-based phase correlation (PC). The improved DCT-based PC method is an extension of DCT-based PC with added blur invariance property. Though fast Fourier transform (FFT)-based methods are efficient for mosaicing of images, they often fail to achieve good quality mosaics when there is illumination variation, blurring or color difference due to imperfect image capturing (image acquisition). Cross correlation (CC) is simple to implement however it has problem when the images have different brightness. Also, the peak of normalized cross correlation is not distinct which gives erroneous results leading to misaligned images in the mosaic. The proposed technique in contrast, is simple, computationally efficient and is able to address the problem of illumination/color variation and blurring. Besides, it contains a single peak of normalized phase correlation corresponding to the percentage of overlap. The experimental analysis for different image sets shows that the method produces better mosaics even for degraded images unlike the other conventional correlation approaches.