Understanding the convolution-intro_working workbook?

Working through video lecture 3 and the convolution-intro_working workbook.

I can understand the first majority of this workbook - the last few cells are losing me.

Do later weeks cover this workbook in more detail?

The code up to this line I have under control.

pool8 = [np.array([pool(correlate(im, rot)) for im in eights]) for rot in rots]

After this I’m not currently sure of the intent. Unpacking the maths and understanding the intent is taking longer than expected.