nuklear VS libvips

Another option that's pure c and a great library is nuklear https://github.com/vurtun/nuklear

If you need the GUI system, then you will be binding against Java and it will be very time consuming. You might be better off looking at some of the young wxWidgets / Qt Android ports. Or simply using a light OpenGL based UI library like Nuklear (or newer).

nuklear - Small, C89, single-header widget toolkit. Public domain.

After some research, I found libvips, a demand-driven, horizontally threaded image processing library. It is designed to run quickly while using as little as memory as possible.

Sharp is a fast and efficient image optimization Node.js module that makes use of the native libvips library.

h2non/bimg can handle both if the underlying libvips is compiled with support for both formats.

if you're using linux (which it doesn't seem so) there's also vispdisp https://github.com/jcupitt/vipsdisp which is based on https://github.com/libvips/libvips which will likely take over how images are decoded in the future for everything, at least methodology wise.

The magic happens by way of a library called Libvips, which contains an ultra-high-speed low-memory image resizer.

imagor uses one of the most efficient image processing library libvips. It is typically 4-8x faster than using the quickest ImageMagick and GraphicsMagick settings.

Try the solutions here: https://github.com/libvips/libvips/issues/2479

in that case maybe take a look at https://github.com/libvips/libvips

libvips v8.6+ or ImageMagick for image analysis and transformations