Keyframing a raster file (Jpeg/PNG.etc) over the main timeline won't allow for smooth left to right (or vice-versa) movement. Somehow the time remapping section gets involved and won't allow it to go smoothly from point A to point B. It seems like a really simple thing to ask. Why does it wiggle around going from Pt A to Pt B? There should be a simple way to turn this off - its stupid. Otherwise one has to spend hours keyframing every single frame to negate this stupid unwanted back and forth motion. Fix this!