Max-pooling is deterministic selection over a small integer window. It returns the exact largest entry, with no averaging and no float.
highlighted = computed this step
A pooling window
Max-pooling looks at a small window and keeps the largest entry. Here the window is the 2 by 2 ReLU map.
pool window 2×2
The exact maximum
The pool window contains 9, 0, 6, and 0. The largest entry is exactly 9.
max(9,0,6,0)=9
Summary
Pooling is a deterministic selection operation. It compares exact integers and returns one exact integer.
max-pool output=9