Every frame stores the delta from the previous frame, in reverse mode
it stores the delta to the next frame. This causes images to use the
wrong delta while assembling in forward mode.
The broken assembling in forward mode will create a small error for
linear motion, because the delta of all frames is approximately the
same in this case. But if you move your finger, stop and then continue
moving in a single scan, the misplaced frames should be visible in
the assembled output.
This could result in false positives and verification failing.
https://bugs.freedesktop.org/show_bug.cgi?id=105027
