Images to vectors: Quick index matrix

Wednesday, April 4. 2007

Images to vectors: Quick index matrix

I found a quicker way to compute the index matrix I mentioned:

> tic; [jj kk]=meshgrid(1:p,1:q); toc Elapsed time is 0.080879 seconds. > size(jj), size(kk) ans = 479 480 ans = 479 480 > tic; idx=mod(b*q*jj+a*p*kk,N)’; toc Elapsed time is 0.129128 seconds. > idx(p,q)=N; %valid index value > imv=zeros(1,N); > tic; for j=1:p; for k=1:q; > imv(idx(j,k)) = im(j,k); > end; end; toc Elapsed time is 6.770042 seconds.

So nothing with 58 seconds anymore.

Posted by Stephan Paukner in Master's Thesis at 09:01 | Comments (0) | Trackback (1)

Defined tags for this entry: mathematics, matlab, octave

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Images to vectors: Correct isomorphism
I always wondered why it didn’t work to compute the dual Gabor atom by using the image-to-vector methods I explained previously [1,2,3]. Dr. Kaiblinger showed me that the correct way was to use that special isomorphism that walks along the diagonal

Weblog: Logbook of Stephan Paukner
Tracked: May 18, 09:56

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