.Dd September 7, 2018
.Dt PNGO 1
.Os "Causal Agency"
.Sh NAME
.Nm pngo
.Nd PNG optimizer
.Sh SYNOPSIS
.Nm
.Op Fl cv
.Op Fl o Ar file
.Op Ar
.Sh DESCRIPTION
.Nm
optimizes PNG files for size.
.Pp
The arguments are as follows:
.Bl -tag -width Ds
.It Fl c
Write to standard output.
.It Fl o Ar file
Write to
.Ar file .
.It Fl v
Output PNG header information.
.El
.Pp
.Nm
performs the following optimizations:
.Bl -bullet
.It
Discard ancillary chunks.
.It
Discard unnecessary alpha channel.
.It
Convert unnecessary truecolor to grayscale.
.It
Palletize color if possible.
.It
Reduce bit depth if possible.
.It
Apply a simple filter heuristic.
.It
Apply zlib's best compresion.
.El
.Sh SEE ALSO
.Xr glitch 1
.Sh CAVEATS
.Nm
does not support interlaced PNGs.