43 lines
1.3 KiB
Python
43 lines
1.3 KiB
Python
import numpy as np
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def OTSU(hist):
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u1=0.0#背景像素的平均灰度值
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u2=0.0#前景像素的平均灰度值
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th=0.0
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#总的像素数目
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PixSum= np.sum(hist)
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#各灰度值所占总像素数的比例
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PixRate=hist / PixSum
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#统计各个灰度值的像素个数
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Max_var = 0
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#确定最大类间方差对应的阈值
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GrayScale = len(hist)
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for i in range(1,len(hist)):#从1开始是为了避免w1为0.
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u1_tem=0.0
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u2_tem=0.0
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#背景像素的比列
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w1=np.sum(PixRate[:i])
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#前景像素的比例
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w2=1.0-w1
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if w1==0 or w2==0:
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pass
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else:#背景像素的平均灰度值
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for m in range(i):
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u1_tem=u1_tem+PixRate[m]*m
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u1 = u1_tem * 1.0 / w1
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#前景像素的平均灰度值
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for n in range(i,GrayScale):
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u2_tem = u2_tem + PixRate[n]*n
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u2 = u2_tem / w2
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#print(u1)
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#类间方差公式：G=w1*w2*(u1-u2)**2
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tem_var=w1*w2*np.power((u1-u2),2)
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#print(tem_var)
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#判断当前类间方差是否为最大值。
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if Max_var<tem_var:
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Max_var=tem_var#深拷贝，Max_var与tem_var占用不同的内存空间。
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th=i
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return th
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