Write PNG meta information


These routines are autoloaded by Image::ExifTool::PNG.


This file contains routines to write PNG metadata.


Compress::Zlib is required to write compressed text.

Existing text tags are always rewritten in their original form (compressed zTXt, uncompressed tEXt or internation iTXt), so pre-existing compressed information can only be modified if Compress::Zlib is available.

Newly created textual information is written in uncompressed tEXt form by default, or as compressed zTXt if the Compress option is used and Compress::Zlib is available (but only if the resulting compressed data is smaller than the original text, which isn't always the case for short text strings).


Copyright 2003-2016, Phil Harvey (phil at

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.