## page was renamed from ReproducibleBuilds/TimestampInPNG
PNG files can capture build time with the [[http://www.w3.org/TR/PNG/#11timestampinfo|tIME]] chunk and custom keywords.

[[https://reproducible.debian.net/issues/timestamps_in_png_issue.html|Known affected packages]]

= Detection =

[[attachment:hedgewars_0.9.21-3.debbindiff.html|Example debbindiff output]]

= Workaround =

DebianPts:strip-nondeterminism since version 0.006 is stripping timestamps from PNG files.

= Solution =

If the PNG is being generated by ImageMagick, some options can be passed to `convert` to inhibit inclusion of the timestamps. Please note that the options have to be passed just before the output filename and `composite` only supports the time chunk removal, for example:

{{{
convert -strip -scale 32x32 input.png output.png # or
convert -scale 32x32 input.png +set date:create +set date:modify -define png:exclude-chunk=time output.png
composite -compose CopyOpacity mask.png input.png -define png:exclude-chunk=time output.png
}}}

[[http://anonscm.debian.org/cgit/pkg-games/hedgewars.git/commit/?id=100bdf42f03a4522c25ced5ee558160283382c7c|Example patch]]