Bill Freeman was talking yesterday at MIA, and we got to see his presentation on the technique used to zoom up on small changes in videos. I decided to try it on a YouTube video. You probably remember this blog entry entitled CAI: Tank Implosion through Robust PCA where we looked at a dramatic scene occuring in an industrial setting through the lens of robust PCA. There, there are numerous situations where tank venting is critical. In the right condition of temperature and the fluid inside, low pressure can set in thereby enabling the crushing of .the tank from the outside/ambiant pressure. Here is that dramatic example from two angles. The video on the left is the original video whereas the one of the right features the processed video with Bill et al's algorithm (see below for the paper and site). One can clearly vizualize the stress waves traveling all around the tank before it eventually buckles.
Phase-based Video Motion Processing by Neal Wadhwa, Michael Rubinstein, Fredo Durand, William T. Freeman
We introduce a technique to manipulate small movements in videos based on an analysis of motion in complex-valued image pyramids. Phase variations of the coefficients of a complex-valued steerable pyramid over time correspond to motion, and can be temporally processed and amplified to reveal imperceptible motions, or attenuated to remove distracting changes. This processing does not involve the computation of optical flow, and in comparison to the previous Eulerian Video Magnification method it supports larger amplification factors and is significantly less sensitive to noise. These improved capabilities broaden the set of applications for motion processing in videos. We demonstrate the advantages of this approach on synthetic and natural video sequences, and explore applications in scientific analysis, visualization and video enhancement.
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