[gdal-dev] Edit geotiff in Gimp and don't lose metadata

[Matt.Wilkie at yukon.ca]

[5]: https://gis.stackexchange.com/a/115560

Oh look at that. Paint.net has supported geotiff tags since at least 2020. However it dumps a stack trace when I try and open the image I used in the Gimp experiment. The size perhaps.

-Matt

From: gdal-dev <gdal-dev-bounces at lists.osgeo.org> On Behalf Of Matt.Wilkie at yukon.ca
Sent: January 13, 2022 10:49 AM
To: gdal-dev at lists.osgeo.org
Subject: [gdal-dev] Edit geotiff in Gimp and don't lose metadata

I am soooo happy today!

I discovered that starting with v2.10.24 Gimp knows about and keeps geotiff tags intact.[0] This means we can use tools like Magic Wand fuzzy select and a host of other tools to quickly fix a host of image issues that are difficult to address using command line tools and/or code.

The big one for me at the moment is dealing with the artifact fringes introduced on image edges when people use jpeg compression.[1] Nearblack is something I keep constantly close by, but it can’t deal with areas that are blocked by horizontal scanning.[2] Today I used Gimp to fix the nodata area for 5.5 GB spot image in about 20 minutes, including time with experimentation. True it needed ~45 GB of memory[3] so this isn’t something I’ll be doing at home, but it worked! [4] And I didn’t need to fart around afterwards restoring georeferencing.[5]

[0]: https://www.gimp.org/news/2021/03/29/gimp-2-10-24-released/
[1]: https://i.imgur.com/LZNn5Zt.png
[2]: https://i.imgur.com/avkILmX.png
[3]: https://i.imgur.com/DVLK1OB.png
[4] https://i.imgur.com/KRfxM0G.png


Some post processing is needed to get things up to our local preferences, for instance Gimp’s alpha channel is 15-20% larger than a gdal external mask and it doesn’t know my new favourite compression method of ZSTD, but this is a huge step forward. I could jump for joy, and maybe after I send this message I will ;-)

Matt Wilkie
Geomatics Developer & Administrator
Environment | Technology, Innovation and Mapping
T 867-667-8133 | Yukon.ca<http://yukon.ca/>
Hours: 08:30-16:30, Mon-Wed: Office, Thu: Remote, Fri: Away.

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