1. Import your render image on a plane (Enable the addon 'Import Image as Planes').
Or simply add a plane and assign your render to it via an image texture. Make sure the plane and image have the same x:y ratio (For eg. 16x9)

2. Add a camera (orthographic) and make sure that the plane perfectly fits the camera view using the 'Orthographic Scale' value.

3. Make the final render resolution equal to the resolution of the image (For eg. 1920x1080)

4. Turn the Compression value under 'Output' down to 0 to prevent the quality loss in re-renders.

5. Now you are good to go. Use Malfunktion effects on your renders and view the results in real-time in the Viewport. Once you are satisfied with the look, simply hit Render, and you are done! :)

Yes, these effects use UV coordinates as their base.

Both, Cycles and Eevee are supported.

No, literally any decent machine can run these effects.

They worked flawlessly on my 8-year-old potato laptop!

As of now, they work from the 'Shader Editor' window only, but that is going to change in the next update.

Absolutely not, any 3d object that has been UV unwrapped will work fine with these effects.

TIP : All primitive objects like cube, sphere, and even Suzanne come pre-unwrapped by default. :)