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灰度直方图.py

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+import numpy as np
+import matplotlib.pyplot as plt
+from PIL import Image
+ 
+def histogram(grayfig):#绘制直方图
+    x = grayfig.size[0]
+    y = grayfig.size[1]
+    ret = np.zeros(256)
+    for i in range(x):  #遍历像素点获得灰度值
+        for j in range(y):
+            k = grayfig.getpixel((i,j))
+            ret[k] = ret[k]+1
+    for k in range(256):
+        ret[k] = ret[k]/(x*y)
+    return ret#返回包含各灰度值占比的数组
+ 
+def histogram_sum(grayfig):#绘制累计直方图
+    x = grayfig.size[0]
+    y = grayfig.size[1]
+    ret = np.zeros(256)
+    for i in range(x):
+        for j in range(y):
+            k = grayfig.getpixel((i,j))
+            ret[k] = ret[k]+1
+    for k in range(1,256):
+        ret[k] = ret[k]+ret[k-1]#累加
+    for k in range(256):
+        ret[k] = ret[k]/(x*y)
+    return ret
+ 
+im = Image.open('./da.jpg')#注意更改路径
+im.show()
+im_gray = im.convert('L')#获得灰度图
+im_gray.show()
+ 
+lenaGrayHist_1 = histogram(im_gray)
+lenaGrayHist_2 = histogram_sum(im_gray)
+ 
+plt.figure()
+plt.rcParams['font.sans-serif'] = ['SimHei']#用来正常显示中文标签
+plt.title("普通直方图")
+plt.bar(range(256),lenaGrayHist_1,color='b')
+plt.show()
+
+plt.figure()
+plt.rcParams['font.sans-serif'] = ['SimHei']
+plt.title("累计直方图")
+plt.bar(range(256),lenaGrayHist_2,color='y')
+plt.show()
+
+#show函数一次只能显示一个，先显示的是蓝色的正常灰度直方图，关掉以后显示的是黄色的累计灰度直方图