Wednesday, April 4. 2007
Images to vectors: Quick index matrix
I found a quicker way to compute the index matrix I mentioned:
CODE:
> 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.
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