Is this valid? flow = rel_flow_to_abs_flow(abs_flow_to_rel_flow (flow))

[hch661100]

Is the following equation valid? My understanding is that the flow should remain consistent when converting to relative values and subsequently reverting to absolute values.
flow = rel_flow_to_abs_flow(abs_flow_to_rel_flow (flow))

I use experiment to analyze the implementation https://github.com/deforum-art/sd-webui-deforum/blob/automatic1111-webui/scripts/deforum_helpers/hybrid_video.py#L594C1-L613C31

and I cannot prove the above equation. The value of output flow somehow is much smaller than the original one. Here is my test:

flow = np.random.randn(250, 250, 2)
mag, ang = cv2.cartToPolar(flow[..., 0], flow[..., 1])
print(np.max(mag)) # 4.503
flow = abs_flow_to_rel_flow(flow, 250, 250)
mag, ang = cv2.cartToPolar(flow[..., 0], flow[..., 1])
print(np.max(mag)) # 0.004
flow = rel_flow_to_abs_flow(flow, 250, 250)
mag, ang = cv2.cartToPolar(flow[..., 0], flow[..., 1])
print(np.max(mag)) # 1.066

Did I miss something?