Is there a way to embed metadata about the license under which a Portable Networks Graphics (PNG) file is being distributed?

For example, this image on this Question on this same Stack Exchange is made available under the CC-BY-NC licence. Can that fact be carried along with the image across computer platforms?

The Creative Commons offers the pages Metadata and Category:Filetype which seem to be about embedding such license metadata. But those pages are not at all clear.

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    Some file formats allow for inserting comments and other data, other file formats do not. JPG, for instance, has provisions for all sorts of information. I'm not sure PNG does, but I wouldn't swear that it doesn't either. Embedding the information is one thing; ensuring that anyone who opens the file reads and accepts any restrictions is another thing. Nothing you can do to the file will make the metadata appear automatically. Jun 20, 2016 at 14:28

1 Answer 1


The PNG format (initially defined in an RFC, now standardised as ISO/IEC 15948:2004) supports tEXt ancillary chunks with a pre-defined 'Copyright' key. These can be used to embed authorship information into the image. No specific 'License' key is identified (section 4.2.7.), but the standard does not prevent the use of custom chunks.

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