There's a -append argument that might be useful: http://www.imagemagick.org/Usage/layers/
But if you want something that processes an arbitrary number of images, you might have to do some programming.
ImageMagick here all the way. From what you wrote, it sounded like the jagged results you were getting were from Gimp, not from ImageMagick, but in case you want to know more about the ImageMagick options for resizing, Google "ImageMagick examples" to find this:
http://www.imagemagick.org/Usage/resize/#resize
Plenty of good stuff there. HOLY CRAP LOOK AT THAT THEY ADDED LIQUID RESCALE! YES!
Whew, excuse me while I calm down. Thank you for sending me to that page today.
But if you just want a shorter example, the ImageMagick command I use is:
convert -geometry 1024x768 -quality 100 infile.jpg outfile.jpg
you probably don't want to use quality 100, that's kind of ridiculous.
Usually I do this kind of thing with for loops that do all the files in a directory, and put them in some other directory. So on unix:
for n in *.jpg; do convert -geometry 1024x768 -quality 100 $n resized/$n; done
don't ever overwrite your original file. I don't use the ImageMagick 'mogrify' command for that reason, only convert.
OK now I'm off to google to find out what 'libre photography' is. I guess it's something about using free tools?
True, but I find launchpad blueprints and bug reports/feature requests a far more productive way to get progress.
https://launchpad.net/inkscape
Make a feature request, and I'll second it and maybe a post to /r/libredesign would help the ball get rolling... Who knows, there could be a keen programmer just waiting to hear those few keen voices...
You are welcome! CC BY-SA 4.0 is a really great license for art, writing, and documentation. I use it for all of that.
https://creativecommons.org/licenses/by-sa/4.0/
I use AGPL 3 for code which is about the same philosophy.
I haven't personally used it, I think may have installed on my phone, but the OS and hardware are too old to use it, or maybe it didn't even install:
>https://play.google.com/store/apps/details?id=org.dandroidmobile.xgimp&hl=en&gl=US
>
>XGimp is an adaptation for Android of the app GIMP (GNU Image Manipulation), which is a freely distributed program for tasks as photo retouching, image composition and image authoring. As a result of that, the app XGimp provides many capabilities. It can be used as a simple paint program, image editor, an expert quality photo retouching program, an image renderer, or an image format converter.