o that the user can sample
color points representing foreground and background.</p></dd>


<dt id="arg-foreground-background">foreground, background<a class="anchor" aria-label="anchor" href="#arg-foreground-background"></a></dt>
<dd><p>A color palette for the foregrond and background,
respectively (optional).</p></dd>


<dt id="arg-index">index<a class="anchor" aria-label="anchor" href="#arg-index"></a></dt>
<dd><p>A character value (or a vector of characters) specifying the
target mode for conversion to b