据我所知，你的代码用颜色B替换了颜色A。你应该看到图像的变化，但不是颜色的交换：颜色A应该消失，颜色B应该出现在它的位置。
要交换两种颜色，您可以尝试以下操作：创建一个示例图像：

import numpy as np
import matplotlib.pyplot as plt

img = np.zeros((12, 12, 3))
col1 = [1, 0, 0]
col2 = [0, 1, 0]
col3 = [0, 0, 0]
img[:] = col1
img[3:9, 3:9] = col3
img[4:8, 4:8] = col2
plt.imshow(img)

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这给出了：

的数据
将col1与col2交换（即红色与绿色）：

mask = [(img == c).all(axis=-1)[..., None] for c in [col1, col2]]
new_img = np.select(mask, [col2, col1], img)
plt.imshow(new_img)

型
测试结果：

的

下面是一个简单的例子：

# Show a 2x2 red image  with a blue  dot (RGB)
image = np.ones((2, 2, 3), dtype=np.uint8)
image[:, :] = [255, 0, 0]
image[0, 0] = [0, 0, 255]
plt.imshow(image)
plt.show()

# Create a mask where the red condition is True
mask = np.all(image == [255, 0, 0], axis=-1)

# Use the mask to change the color where the condition is True
image[mask] = [0, 255, 0]

# Show a 2x2 green image with a blue  dot (RGB)
plt.imshow(image)
plt.show()

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那么这个呢，基于this solution

import numpy as np
from PIL import Image

im = Image.open('fig1.png')
data = np.array(im)

r1, g1, b1 = 0, 0, 0 # Original value
r2, g2, b2 = 255, 255, 255 # Value that we want to replace it with

red, green, blue = data[:,:,0], data[:,:,1], data[:,:,2]
mask1 = (red == r1) & (green == g1) & (blue == b1)
mask2 = (red == r2) & (green == g2) & (blue == b2)
data[:,:,:3][mask1] = [r2, g2, b2]
data[:,:,:3][mask2] = [r1, g1, b1]

im = Image.fromarray(data)
im.save('fig1_modified.png')

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