 here because it makes my head hurt.</li>
<li>When constructing the displacement maps I used <code>ch_alpha()</code> to make clear that we should use the transparency value of each pixel as the basis for the displacement. That makes sense in this case because transparency is the thing that varies across the image.</li>
<li>The <code>x_scale</code> and <code>y_scale</code> parameters specify the number of pixels to shift. Specifically, setting <code>x_scale = 150</code> means that the maximum difference in t