Is anyone aware of a package, available in the opkg repositories, that would allow me to resize a jpeg image? It looks like imageMagick used to be in the repo, but no longer is...?
opkg install jpeg-tools jpegtran --help
Graphicsmagick is preferred if you faster processing compared to Imagemagick although it might use a bit more memory, both are available in master branch.
Ah great. The man page I found for that already didn't list "scale" but it looks like it is now a valid parameter. Thanks!
Ah... "An implementation of the JPEG SmartScale extension is required for this feature. SmartScale enabled JPEG is not yet widely implemented, so many decoders will be unable to view a SmartScale extended JPEG file at all."
I will see if I can use Graphicsmagick!
I've used php7-mod-gd for image manipulation, usually scaling and adding a watermark for serving on a web page.
With a web server you would use it with php7-cgi, for command line use it with php7-cli, so depending on your requirements this is possibly a good way forward.
There are lots of online tutorials too.
Hope this helps