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.Dd September 17, 2018
.Dt PNGO 1
.Os
.
.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 and alpha 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.