By accident I discovered that you can import .jpg images into Pencil2D, the program helpfully automatically converts them into .png.
I like this feature, very useful!
Incidentally I wanted to scroll the image. I created two frames in the camera layer and the result was a jump from 1 position to the other.
I found you need to create frames, but they don’t need to be on the same layer, if they’re blank you get a smooth scroll, and the .pclx file is much smaller than if the frames were on the layer of the .png file.
Once the .pclx file is loaded you have 2 select the layer with the blank frames to activate the scroll.
This probably wasn’t a design feature, but it’s an excellent 1.