The Taub Faculty of Computer Science Events and Talks

Nikolay Skarbnik Department of Electrical Engineering The Technion Abstract: Signal's phase is a non-trivial quantity. It is therefore often ignored in favor of signal's magnitude. However, phase conveys more information regarding signal structure than magnitude does, especially in the case of images. It is therefore essential to use phase information in various signal/image processing schemes as well as in computer vision. This is true for global phase and, even more so, for local phase. The latter is solely sufficient for signal/image representation, while totally ignoring the magnitude information. We first address the importance of phase with reference to several examples. We then present cases where local phase-based solutions are compared with magnitude-based ones. We argue that the phase has several advantages over magnitude: It is unit-less bounded quantity, thus eliminating the need for thresholds. Local phase shows immunity to several types of noise, and changes in signal strength (such as illumination in the case of images). We argue and demonstrate that due to the above-listed advantages, local phase is a powerful tool for signal/image analysis. Several novel local phase-based edge detection schemes are presented, discussed and compared with traditional edge detection schemes. We address the performance of our local phase-based scheme in the context of several applications such as: detection of man-made environment, image denoising and segmentation. * Master thesis under the supervision of prof. Yehoshua Y. Zeevi The talk will take place On Tuesday, 1/09/2009 at 11:30 in Room 1061 Electrical Eng. Building Technion City