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Add support for metadata in PNG/APNG images
Posted: Tue Jan 31, 2023 12:13 pm
by Euphoria
As PNG pretty much the most used lossless image format these days, so is the importance and usage of PNG Metadata has grown.
Please add support for viewing, editing, and saving PNG Metadata. Included is an example image containing metadata critical to the context of the image.

- Sample PNG image containing critical image metadata.
- 02852-20230129221459-Heun-step_45-2324588829.png (374.98 KiB) Viewed 6858 times
Re: Add support for metadata in PNG/APNG images
Posted: Fri Feb 03, 2023 9:36 am
by xnview
sorry but there is no EXIF/XMP/IPTC metadata in this file
Re: Add support for metadata in PNG/APNG images
Posted: Sat Feb 04, 2023 12:35 pm
by WinnieW
PNG format use a native metadata format, there are called metadata chunks.
http://www.libpng.org/pub/png/spec/1.2/PNG-Chunks.html
The PNG in the first post has metadata specified as tEXT chunk
Re: Add support for metadata in PNG/APNG images
Posted: Tue Feb 28, 2023 6:23 pm
by pitti911
This issue is related to
viewtopic.php?f=82&t=42770&p=174462&hilit=chunk#p174462
as well. Also, the properties window in the browser is already able to display the mentioned data. That points to some kind of (rudimentary) capabilities in that direction already.
Also worth mentioning: The above image is made with stable diffusion, so while this chunk seems to have an internal structure that's going to be different depending on the actual content of the text chunk.
With that in mind, some basic parsing/scripting capabilites would be nice for View/fullscreen mode information overlay.
Re: Add support for metadata in PNG/APNG images
Posted: Wed Mar 22, 2023 3:35 pm
by crowley
Hi,
Is it possible to add a function to edit these PNG metadata "Chunks"? It would be quite useful to be able to edit this via the properties panel that already shows the metadata.
My current workflow for editing the metadata is via python which is a tad more cumbersome

Re: Add support for metadata in PNG/APNG images
Posted: Mon Oct 30, 2023 8:30 pm
by XnTriq
I did a few tests and posted the
results.
XnView MP was the only program capable of saving metadata as
eXIf chunk
https://en.wikipedia.org/wiki/PNG#JPEG wrote:While the PNG specification does not explicitly include a standard for embedding Exif image data from sources such as digital cameras, the preferred method for embedding EXIF data in a PNG is to use the non-critical ancillary chunk label
eXIf.
Related:
EXIF support in PNG