Compute Structure Tensor


As i know, Structure Tensor is:

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How i compute $ I_x^2, I_y^2, I_xI_y$ . I used Hadamard product for compute $ I_x^2, I_y^2, I_xI_y$ . But if i use Hadamard product i will get $ det(M) = 0$ . I’m stuck in here for too long. Can anyone explain for me?. Thank you.