Computer Vision News - February 2017

32 Computer Vision News Research Research Riesz Pyramids for Fast Phase-Based Video Magnification Every month, Computer Vision News reviews a research from our field. This month we have chosen to review Riesz Pyramids for Fast Phase-Based Video Magnification , a research paper presenting a new compact image pyramid representation, the Riesz pyramid, that can be used for real-time phase-based motion magnification. We are indebted to the authors ( Neal Wadhwa, Michael Rubinstein, Frédo Durand and William T. Freeman ) allowing us to use their images to illustrate this review. The website of the research is here . Minor changes in videos, unnoticeable by the human eye, may contain valuable information that we would like to capture. This research utilizes phase-based motion magnification algorithms to enhance these small changes and reveal them. The main idea behind phase-based motion amplification is to magnify the temporal changes using spatio-temporal processing. The paper introduces a new compact image pyramid representation, the Riesz pyramid : by approximating the Riesz-pyramid, the authors achieve real-time phase-based motion magnification. Magnifications created with this method are comparable in quality to those created using the steerable pyramid. The method's impressive real-time results are demonstrated in this award- winning video (Best Demo at CVPR 2014!) in which an excited wine glass's oscillations are made visible. Don’t miss it! The concept of phase-based magnification: To illustrate the notion of Phase-based video motion magnification, let's consider a 1D sinusoid signal and it's slightly shifted version. The method quantifies the change between the two successive frames by computing the change in phase. This change in phase is translated into amplitude amplification. A process for doing this was proposed by Wu et al. in 2012, using Eulerian transformation. Introduction: Let’s keep in mind that the purpose of the method reviewed is to propose a new fast and efficient image pyramid representation, the Riesz pyramid, that is suitable for real-time phase-based motion magnification. Riesz transform is a generalization of one-dimensional Hilbert transform