Example shear filter functions , for filter and PSF size w = 3, p = 2, (κ = 0). Integrating an image multiplied with the filter function for a particular shear (g₁,g₂) yields the weighted second moments the image would have had if it had been sheared by that amount before seeing convolution. The central box is 25 units on a side, and the dashed line indicates the maximum shear value that can be applied for the given w and p (see Eq. (18)). Red is positive, blue is negative. Left: filters corresponding to Q_xx−Q_yy. Right: filters corresponding to Q_xy.