How do i calculate hessian matrix for an image?

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suresh G
suresh G 2013-3-20
评论： Ismail Zouaoui 2019-7-23
i need to calculate hessian matrix manually.can anyone help?

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采纳的回答

David Legland
David Legland 2013-3-20
Hi, you need to compute second derivatives in each direction, using something like:
[gx, gy] = gradient(double(img));
[gxx, gxy] = gradient(gx);
[gxy, gyy] = gradient(gy);
The coefficients of the hessian matrix for each pixel are given by gxx, gxy and gyy.
regards
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Zirui WANG
Zirui WANG 2019-1-11
Thanks a lot for the answer, but I think there is a small order issue in the last line?
I think the last line should be
[gyx, gyy] = gradient(gx)
instead of
[gxy, gyy] = gradient(gx)
?

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Yongkai liu
Yongkai liu 2018-12-24
Thanks! It seems that in practice, we use the second derivative of gassian filter convoluted on image to get the hessian matrix feature of image.

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