Using an image as a flat backdrop? I'm using 2.79 and Cycles render.

I'm making a flat, cartoony scene, and would like to essentially use the below image as a horizon/sky texture. I want the image to display undistorted by perspective, independent of the camera/view angle.

I attempted to do this using the World tab > image texture, but I couldn't get it to do anything like what I wanted (under most settings it just shows flat colours from the image rather than the full thing, and one setting gives a kind of distorted polar coordinates-style effect, which is again different to what I'm going for)

I have tried using textured flat planes and cylinders, but these were both hard to set up within the camera view in the way I wanted, and ended up distorting the image texture.

Sorry if this is a basic question - I have tried searching for tutorials on this but nothing I found answered my question, perhaps because I don't know the proper name for this technique.

Thanks in advance!
You can set the world node tree from the &quot;window&quot; texture coordinates (so no distortions).
Then use an image texture (not environment texture).
The image won't move when the camera moves.