What does $G_{\sigma'}$ mean here? How is it related to computing the sums of the products of derivatives at each pixel?
motoole2
Step 3 performs a convolution with a Gaussian filter (with standard deviation $\sigma'$). Any given pixel in the image $S_{x^2}$ is therefore the weighted sum of pixels in a corresponding neighborhood in $I_{x^2}$. If you wanted to compute a straight sum (and not a weighted sum), you can replace the Gaussian filter with a box filter.
What does $G_{\sigma'}$ mean here? How is it related to computing the sums of the products of derivatives at each pixel?
Step 3 performs a convolution with a Gaussian filter (with standard deviation $\sigma'$). Any given pixel in the image $S_{x^2}$ is therefore the weighted sum of pixels in a corresponding neighborhood in $I_{x^2}$. If you wanted to compute a straight sum (and not a weighted sum), you can replace the Gaussian filter with a box filter.