Modulating a 2D-Gaussian

I tell a little about what I did with Octave during the last days. This is the first part and it's about creating a video of a modulated Gaussian. The second part is about doing FFT's of time-frequency shifted Gaussians.

I figured out how to merge images into a video stream. I rely on Linux tools rather than trying to do it from within Octave, because I don't know whether libraries for creating videos are somehow available there. However, I wrote an M-file which creates images of a modulated 2D-Gaussian. The 2D-frequency changes by going on a spiral in the complex plane starting from the origin. This yields a modulation which is rotating while the line-pattern gets narrower:

rotgauss.flv

I merged the bunch of 900 images to a video by using MEncoder, the open-source encoder from the MPlayer suite. I did it this way:

CODE:

$ mencoder mf://out*png -ovc lavc -mf fps=25 -o rotgauss.avi

I know, the usage of a proprietary container format is a contradiction to using open-source tools, but I only want to care about such details later.

I won't publish the M-file here, as it's too basic.

Posted by Stephan Paukner in Master's Thesis at 18:11 | Comments (0) | Trackbacks (2)

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Logbook of Stephan Paukner on : Time-frequency shifts of a 2D-Gaussian

The modulated Gaussian I showed previously was just illustratory and did not consider mathematical properties such as FT-invariance. For that, it has to be periodized, normalized and centered at the borders. The MATLAB script gaussnk.m by N.&nbsp;Kaibling

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I finally managed to scale the reconstructed images appropriately such that one can see at what locations certain 2D-frequencies occur. I FT&#8217;ed an image of a zebra and &#8220;windowed&#8221; the FT with a shifted Gaussian. Doing the inverse FT of th

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