def quantize_flow(flow, max_val=0.02, norm=True):
"""Quantize flow to [0, 255].
After this step, the size of flow will be much smaller, and can be
dumped as jpeg images.
Args:
flow (ndarray): (h, w, 2) array of optical flow.
max_val (float): Maximum value of flow, values beyond
[-max_val, max_val] will be truncated.
norm (bool): Whether to divide flow values by image width/height.
Returns:
tuple[ndarray]: Quantized dx and dy.
"""
h, w, _ = flow.shape
dx = flow[..., 0]
dy = flow[..., 1]
if norm:
dx = dx / w # avoid inplace operations
dy = dy / h
# use 255 levels instead of 256 to make sure 0 is 0 after dequantization.
flow_comps = [
quantize(d, -max_val, max_val, 255, np.uint8) for d in [dx, dy]
]
return tuple(flow_comps)
def quantize_flow(flow, max_val=0.02, norm=True):
'Quantize flow to [0, 255].\n\n After this step, the size of flow will be much smaller, and can be\n dumped as jpeg images.\n\n Args:\n flow (ndarray): (h, w, 2) array of optical flow.\n max_val (float): Maximum value of flow, values beyond\n [-max_val, max_val] will be truncated.\n norm (bool): Whether to divide flow values by image width/height.\n\n Returns:\n tuple[ndarray]: Quantized dx and dy.\n '
(h, w, _) = flow.shape
dx = flow[(..., 0)]
dy = flow[(..., 1)]
if norm:
dx = (dx / w)
dy = (dy / h)
flow_comps = [
quantize(d, (-max_val), max_val, 255, np.uint8) for d in [dx, dy]
]
return tuple(flow_comps)