十二、Matplotlib的 imshow使用方法

女爷i 2023-06-15 09:56 1阅读 0赞

**目录**

1、画灰度图像

2、画彩色图像

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# 1、画灰度图像 #

# encoding: utf-8
    import cv2
    import matplotlib.pyplot as plt
    import numpy as np
    
    def show_img(name="test",img=None):
        plt.figure()
        plt.imshow(img)
        plt.title(name)
        plt.show()
    
    
    if __name__ == '__main__':
        path = r"lena.jpg"
        img = cv2.imread(path)
        gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
        ret,binary = cv2.threshold(gray,127,255,0)
        """测试使用不同的cmap，画彩色和灰度图像"""
        # 使用cmap，默认值显示彩色图像，不正确
        plt.subplot(2,2,1),plt.imshow(img),plt.axis('off')#关闭坐标轴
        # 使用cmap='gray'显示彩色图像，不正确
        plt.subplot(2,2,2),plt.imshow(img,cmap='gray'),plt.axis('off')#关闭坐标轴
        # 使用cmap，默认值显示灰度图像，不正确
        plt.subplot(2,2,3),plt.imshow(gray),plt.axis('off')#关闭坐标轴
        # 使用cmap='gray',默认值显示彩色图像，正确
        plt.subplot(2,2,4),plt.imshow(gray,'gray'),plt.axis('off')#关闭坐标轴
        plt.show()

# 2、画彩色图像 #

注意通道的顺序

# encoding: utf-8
    import cv2
    import matplotlib.pyplot as plt
    import numpy as np
    
    def show_img(name="test",img=None):
        plt.figure()
        channel = img.shape
        if channel == 3:
            b, g, r = cv2.split(img)
            img = cv2.merge([r, g, b])
        plt.imshow(img)
        plt.title(name)
        plt.show()
    
    
    if __name__ == '__main__':
        path = r"lena.jpg"
        img = cv2.imread(path)
        gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
        ret,binary = cv2.threshold(gray,127,255,0)
        b,g,r = cv2.split(img)
        img2 = cv2.merge([r,g,b])
    
        # 使用cmap，默认值显示彩色图像，不正确
        plt.subplot(1,2,1),plt.imshow(img),plt.axis('off')#关闭坐标轴
        # 使用cmap='gray'显示彩色图像，不正确
        plt.subplot(1,2,2),plt.imshow(img2),plt.axis('off')#关闭坐标轴
        plt.show()

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