python - 黑色时如何将BGR图像设置为另一个图像？

Question

我有 2 个 BGR 图像。一个主要是黑色。我希望将所有黑色像素设置为另一个图像的像素。

u_v[:,:,:] = prev_frame[:,:,:] # Only where u_v[:,:] = black/(0,0,0) 

Answer 1

我们可以创建 black 的掩码像素通过寻找 ALL沿最后一个轴的零点 (axis=-1)通过与 0 进行比较然后 ALL reduce沿着它——

mask = (u_v==0).all(axis=-1)

然后，将此掩码用于 boolean-indexing从 prev_frame 中选择并分配到 u_v -

u_v[mask] = prev_frame[mask]

示例运行说明

1] 输入:

In [148]: u_v
Out[148]: 
array([[[0, 0, 0], # first pixel set as all zeros for testing
        [2, 1, 1]],

       [[1, 2, 2],
        [0, 3, 1]]])

In [149]: prev_frame
Out[149]: 
array([[[0, 2, 1], <== this one is to be copied over to u_v
        [3, 1, 0]],

       [[2, 2, 3],
        [2, 0, 1]]])

2]黑色像素的掩码:

In [150]: mask = (u_v==0).all(axis=-1)

In [151]: mask
Out[151]: 
array([[ True, False], # first element is True as first pix was black
       [False, False]], dtype=bool)

3] bool 索引选择和分配:

In [152]: u_v[mask] = prev_frame[mask]

In [153]: u_v
Out[153]: 
array([[[0, 2, 1], <=== copied from prev_frame
        [2, 1, 1]],

       [[1, 2, 2],
        [0, 3, 1]]])