a 16x16 matrix; and three
different sizes of 45-degree clustered-dot dither (<B>-cluster3</B>,
<B>-cluster4</B>, <B>-cluster8</B>).

<p>A space filling curve halftoning method using the Hilbert curve is
also available (<B>-hilbert</B>).

<P>Floyd-Steinberg will almost always give the best looking results;
however, looking good is not always what you want.  For instance,
thresholding can be used in a pipeline with the <b>pnmconvol</b> tool,
for tasks like edge and peak detection.  And clustered-dot dithering