<code>"xor"</code> filter is easy to visualise in this case. If a pixel is white in exactly <em>one</em> of the two inputs (the tree or the triangle), that pixel will also be white in the output. Otherwise that pixel will be transparent. That gives us this:</p>
<div class="cell" data-layout-align="center" data-fig.dpi="300">
<div class="sourceCode cell-code" id="cb31"><pre class="sourceCode r code-with-copy"><code class="sourceCode r"><span id="cb31-1"><a href="#cb31-1" aria-hidden="true" tabindex="-1"></a>