+.It Fl F , \-format Ar format
+Select the desired output format. Some formats may not be available depending
+on the compile-time settings of
+.Nm .
+If this option is not specified, the default is the first in the following list
+which is enabled at build time.
+.Bl -column -offset indent ".Em Format"
+.It Em Format Ta Em Description
+.It png Ta
+Output images in Portable Network Graphics (PNG) format. This is is a
+compressed format which is well-supported by other tools. All features of
+.Nm
+are supported with this format.
+.It pam Ta
+Output images in Netpbm PAM format. This is a simple uncompressed binary image
+format supporting RGB and alpha channels. All features of
+.Nm
+are supported with this format.
+.It ppm Ta
+Output image colour data in Netpbm "plain" PPM format. This is a simple
+7-bit clean uncompressed RGB format. It does not support transparency, so
+images will have transparent pixels replaced with black. This format is
+rather inefficient and provided mainly for testing.
+.It pbm Ta
+Output image mask data in Netpbm "plain" PBM format. This is a simple 7-bit
+clean uncompressed bitmap format. It does not support colour data; instead,
+bitmap values represent whether or not a pixel is transparent. Black (1)
+pixels are transparent, white (0) pixels are opaque. This format is extremely
+inefficient and provided mainly for testing.
+.El
+.It Fl f , \-file Ar path