How can I get the previous frame from a scene capture?

I am trying to implement a postprocess effect that is essentially temporal ‘image subtraction’ - subtracting the current image from the previous to track changed pixels.

I have a scene capture component linked to a render target, but when I associate this to texture parameters, it’s continuously rendering to all textures it is linked to even when I try to introduce delays. Is there any way of getting the previous frame, by rendering once, and keeping it in a buffer somehow?

You can’t read a render target while it is being drawn to but you can use 2 render targets ping pong style by switching the target in the capture component and the texture parameter every frame (alternating). Not sure what you are trying to accomplish, but pixel motion is also already available as “velocity” in the post process material.