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Topic: sub-pixel shifting of a matrix
Replies: 14   Last Post: Feb 7, 2013 12:23 PM

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Bruno Luong

Posts: 9,822
Registered: 7/26/08
Re: sub-pixel shifting of a matrix
Posted: Feb 6, 2013 5:49 PM
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"Matt J" wrote in message <keuln5$onb$1@newscl01ah.mathworks.com>...

>
> Maybe, but only because there are some funny sub-optimal things happening inside conv2 implementation-wise, and because the interpolation kernel here happens to be small. There's no way the 3rd version below should be the slowest.


Of course. The reason is obvious: 2+2 = 2*2, but 10+10 << 10*10.

Bilinear interpolation - as we discussed here - requires kernel of 2. So there is no need to decompose the convolution in tensorial at the price of memory parsing twice.

Bruno



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