Python 如何将 RGB PIL 图像转换为具有 3 个通道的 numpy 数组？
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How to convert RGB PIL image to numpy array with 3 channels?
提问by Dims
I am loading image with the following code
我正在使用以下代码加载图像
image = PIL.Image.open(file_path)
image = np.array(image)
It works, but the size of array appears to be (X, X, 4), i.e. it has 4 layers. I would like normal RGB layers. Is it possible?
它可以工作，但数组的大小似乎是(X, X, 4)，即它有 4 层。我想要普通的 RGB 层。是否可以？
UPDATE
更新
I found that just removing 4th channel is unsufficcient. The following code was required:
我发现仅仅删除第 4 个通道是不够的。需要以下代码：
image = PIL.Image.open(file_path)
image.thumbnail(resample_size)
image = image.convert("RGB")
image = np.asarray(image, dtype=np.float32) / 255
image = image[:, :, :3]
Why?
为什么？
回答by keredson
The fourth layer is the transparency value for image formats that support transparency, like PNG. If you remove the 4th value it'll be a correct RGB image without transparency.
第四层是支持透明度的图像格式的透明度值，如 PNG。如果您删除第 4 个值，它将是一个没有透明度的正确 RGB 图像。
EDIT:
编辑：
Example:
例子：
>>> import PIL.Image
>>> image = PIL.Image.open('../test.png')
>>> import numpy as np
>>> image = np.array(image)
>>> image.shape
(381, 538, 4)
>>> image[...,:3].shape
(381, 538, 3)
