在python中更改像素的颜色

我想把图像中任意一个20×20像素正方形的颜色改成纯红色。图像数据只是一个数组。要将正方形更改为红色，我需要在感兴趣的正方形中将红色层设置为其最大值，将绿色和蓝色层设置为零。不知道该怎么做

import numpy as np
import matplotlib.pyplot as plt

imageArray = plt.imread('earth.jpg')
print('type of imageArray is ', type(imArray))
print('shape of imageArray is ', imArray.shape)

fig = plt.figure()
plt.imshow(imageArray)

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要在图像上绘制正方形，可以使用matplotlib中的

矩形

看

如果确实要更改每个像素，可以迭代行/列，并将每个像素设置为[255，0，0]。下面是一个示例（如果您朝这个方向走，您将希望包括IndexError的异常处理）：

编辑：

更改像素值的更有效解决方案是使用阵列切片

def drawRedSquare(image, location, size):

    x,y = location
    w,h = size
    image[y:y+h,x:x+w] = np.ones((w,h,3)) * [255,0,0]

    return image

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您可以这样做：

from PIL import Image
picture = Image.open(your_image)
pixels = picture.load()

for i in range(10,30): # your range and position
    for j in range(10,30):
        pixels[i,j] = (255, 0, 0)

picture.show()

---

你是怎么看这张图片的？

def drawRedSquare(image, location, size):

    x,y = location
    w,h = size
    image[y:y+h,x:x+w] = np.ones((w,h,3)) * [255,0,0]

    return image

from PIL import Image
picture = Image.open(your_image)
pixels = picture.load()

for i in range(10,30): # your range and position
    for j in range(10,30):
        pixels[i,j] = (255, 0, 0)

picture.show()

import numpy as np
import matplotlib.pyplot as plt

imageArray = plt.imread('earth.jpg')

# Don't use loops. Just use image slicing since imageArray is a Numpy array.
# (i, j) is the row and col index of the top left corner of square.
imageArray[i:i + 20, j:j + 20] = (255, 0, 0)