我尝试合并零通道以创建具有单个通道的图像时出错

Question

我正在尝试读取图像，然后仅保留red输出图像中的通道。这是我所做的：color = cv2.imread("lohri.jpg")b,g,r = cv2.split(color)zeros = np.zeros([b.shape[0], b.shape[1]])# Make other 2 channels as zerosonly_red = cv2.merge((zeros, zeros, r))但是当我这样做时，我收到一条错误消息：OpenCV(3.4.1) Error: Assertion failed (mv[i].size == mv[0].size && mv[i].depth() == depth) in merge, file /io/opencv/modules/core/src/merge.cpp, line 458Traceback (most recent call last):File "inspect.py", line 23, in <module>  only_red = cv2.merge((zeros, zeros, r))  cv2.error: OpenCV(3.4.1) /io/opencv/modules/core/src/merge.cpp:458:   error: (-215) mv[i].size == mv[0].size && mv[i].depth() == depth in   function merge我无法理解这样做的原因。为什么我会收到这个错误？

Answer 1

这是因为虽然您的零形状是正确的，但很可能是数据类型不匹配。Numpy Zeros文档的默认数据类型为numpy.float64. 只需dtype为您的案例传递参数。

color = cv2.imread("lohri.jpg")

b,g,r = cv2.split(color)

zeros = np.zeros(b.shape[0], b.shape[1]], dtype = b.dtype)

#Note that the dtype is most likely np.uint8, and you can use that instead too if you prefer

#zeros = np.zeros([b.shape[0], b.shape[1]], dtype = np.uint8)

#Also note that you can pass shape tuple directly.

#zeros = np.zeros(b.shape, dtype = np.uint8)

# Make other 2 channels as zeros

only_red = cv2.merge((zeros, zeros, r))

编辑：您还可以使用np.zeros_like正确的形状和数据类型创建数组，这也使代码更加简洁明了。谢谢马克！

color = cv2.imread("lohri.jpg")

b,g,r = cv2.split(color)

zeros = np.zeros_like(b)

only_red = cv2.merge((zeros, zeros, r))