The same 3 × 3 kernel, the same 8 × 8 input — only the step size changes. At stride 1 the window visits every position and the map keeps its size. At stride 2 it visits every second position in each direction: a quarter of the work, half the size, and the skipped centres stay grey. The output is drawn at the input's scale, so each output cell covers the stride of pixels it stands for.