giant.image_processing.HORIZONTAL_KERNEL

giant.image_processing.HORIZONTAL_KERNEL = array([[ 1,  0, -1],        [ 2,  0, -2],        [ 1,  0, -1]])

The horizontal Sobel kernel for convolving with an image when computing the horizontal image gradients.

https://www.researchgate.net/publication/239398674_An_Isotropic_3x3_Image_Gradient_Operator