Python 将灰度图像转换为 3 通道图像
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convert a grayscale image to a 3-channel image
提问by Dylan
I want to convert a gray-scale image with shape (height,width)to a 3 channels image with shape (height,width,nchannels). The work is done with a for-loop, but there must be a neat way. Here is a piece code in program, can someone give a hint. please advice.
我想将具有 shape 的灰度图像转换为具有 shape(height,width)的 3 通道图像(height,width,nchannels)。工作是用 完成的for-loop，但必须有一个整洁的方式。这是程序中的一段代码，有人可以给出提示。请指教。
30 if img.shape == (height,width): # if img is grayscale, expand
31 print "convert 1-channel image to ", nchannels, " image."
32 new_img = np.zeros((height,width,nchannels))
33 for ch in range(nchannels):
34 for xx in range(height):
35 for yy in range(width):
36 new_img[xx,yy,ch] = img[xx,yy]
37 img = new_img
回答by Chris Mueller
You can use np.stackto accomplish this much more concisely:
您可以使用np.stack更简洁地完成此操作：
img = np.array([[1, 2], [3, 4]])
stacked_img = np.stack((img,)*3, axis=-1)
print(stacked_img)
# array([[[1, 1, 1],
# [2, 2, 2]],
# [[3, 3, 3],
# [4, 4, 4]]])
