.Dd September 21, 2021
.Dt PNGO 1
.Os
.
.Sh NAME
.Nm pngo
.Nd PNG optimizer
.
.Sh SYNOPSIS
.Nm
.Op Fl acgv
.Op Fl b Ar depth
.Op Fl o Ar file
.Op Ar
.
.Sh DESCRIPTION
.Nm
optimizes PNG files for size
by performing the following:
.Pp
.Bl -enum -compact
.It
Discard ancillary chunks.
.It
Discard unnecessary alpha channel.
.It
Convert unnecessary truecolor to grayscale.
.It
Palletize color if possible.
.It
Reduce unnecessary bit depth.
.It
Apply a simple filter type heuristic.
.It
Apply zlib's best compression.
.El
.
.Pp
The arguments are as follows:
.Bl -tag -width Ds
.It Fl a
Always discard the alpha channel.
.It Fl b Ar depth
Reduce bit depth to
.Ar depth
or lower.
.It Fl c
Write to standard output.
.It Fl g
Convert to grayscale.
.It Fl o Ar file
Write to
.Ar file .
.It Fl v
Print header information and sizes
to standard error.
.El
.
.Sh SEE ALSO
.Xr glitch 1
.
.Sh BUGS
.Nm
does not support interlaced PNGs.