python四个性能检测工具,包括函数的
526 2023-04-03 05:09:06
均匀性度量图像分割是图像像素分割的一种方法,当然还有其他很多的方法。这里简单的介绍下其原理和实现代码【有源码】
其流程大概分为一下几步
1、确定一个阈值
2、计算阈值两边的像素个数、占比、以及方差
3、将两边的方差和占比想乘再相加
4、循环1~3的步骤
下面以这个例子为示例做一个演示
计算公式:
阈值为: 1
阈值左边值为: [1, 1, 0, 0, 0] 均值: 0.08
阈值右边值为: [3, 9, 9, 8, 2, 3, 7, 3, 3, 6, 6, 4, 6, 8, 2, 5, 2, 9, 2, 6] 均值: 4.12
阈值左边方差为: 1.712
阈值右边方差为: 147.76800000000003
方差和比例相乘为: 118.55680000000002
阈值为: 2
阈值左边值为: [1, 2, 1, 0, 2, 0, 2, 2, 0] 均值: 0.4
阈值右边值为: [3, 9, 9, 8, 3, 7, 3, 3, 6, 6, 4, 6, 8, 5, 9, 6] 均值: 3.8000000000000007
阈值左边方差为: 11.440000000000003
阈值右边方差为: 150.04
方差和比例相乘为: 100.144
阈值为: 3
阈值左边值为: [1, 3, 2, 1, 3, 3, 3, 0, 2, 0, 2, 2, 0] 均值: 0.8799999999999999
阈值右边值为: [9, 9, 8, 7, 6, 6, 4, 6, 8, 5, 9, 6] 均值: 3.3200000000000003
阈值左边方差为: 25.347200000000004
阈值右边方差为: 186.14879999999997
方差和比例相乘为: 102.53196799999999
阈值为: 4
阈值左边值为: [1, 3, 2, 1, 3, 3, 3, 0, 4, 2, 0, 2, 2, 0] 均值: 1.0399999999999998
阈值右边值为: [9, 9, 8, 7, 6, 6, 6, 8, 5, 9, 6] 均值: 3.16
阈值左边方差为: 31.0624
阈值右边方差为: 199.56159999999997
方差和比例相乘为: 105.20204799999998
阈值为: 5
阈值左边值为: [1, 3, 2, 1, 3, 3, 3, 0, 4, 2, 0, 5, 2, 2, 0] 均值: 1.2399999999999998
阈值右边值为: [9, 9, 8, 7, 6, 6, 6, 8, 9, 6] 均值: 2.96
阈值左边方差为: 41.18400000000001
阈值右边方差为: 213.536
方差和比例相乘为: 110.12480000000001
阈值为: 6
阈值左边值为: [1, 3, 2, 1, 3, 3, 3, 6, 0, 6, 4, 6, 2, 0, 5, 2, 2, 6, 0] 均值: 2.1999999999999997
阈值右边值为: [9, 9, 8, 7, 8, 9] 均值: 2.0
阈值左边方差为: 88.96000000000002
阈值右边方差为: 244.0
方差和比例相乘为: 126.16960000000002
阈值为: 7
阈值左边值为: [1, 3, 2, 1, 3, 7, 3, 3, 6, 0, 6, 4, 6, 2, 0, 5, 2, 2, 6, 0] 均值: 2.4800000000000004
阈值右边值为: [9, 9, 8, 8, 9] 均值: 1.7200000000000002
阈值左边方差为: 103.488
阈值右边方差为: 237.87199999999996
方差和比例相乘为: 130.3648
阈值为: 8
阈值左边值为: [1, 3, 8, 2, 1, 3, 7, 3, 3, 6, 0, 6, 4, 6, 8, 2, 0, 5, 2, 2, 6, 0] 均值: 3.12
阈值右边值为: [9, 9, 9] 均值: 1.08
阈值左边方差为: 143.4368
阈值右边方差为: 188.17919999999998
方差和比例相乘为: 148.805888
2
100.144
结论:
最后我们发现 以像素点为4的来分的时候,两边方差与占比的乘积最小,因此最佳阈值就是 【2】
源码
?123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263import
numpy as np
#
data
=
[
1
,
3
,
9
,
9
,
8
,
2
,
1
,
3
,
7
,
3
,
3
,
6
,
0
,
6
,
4
,
6
,
8
,
2
,
0
,
5
,
2
,
9
,
2
,
6
,
0
]
# data = [0, 1, 3, 1, 5,
# 7, 8, 9, 7]
max
=
np.
max
(data)
length
=
len
(data)
num_min_data
=
[]
num_max_data
=
[]
arr_var
=
0
min_result
=
1000
result_threshold
=
0
def
myMean(arrs):
resultss
=
0.0
data
=
{}
for
i
in
arrs:
data[i]
=
data.get(i,
0
)
+
1
for
i
in
data:
resultss
+
=
i
*
(data[i]
/
length)
return
resultss
def
fz(arrs):
results
=
0.0
mean
=
myMean(arrs)
for
i
in
arrs:
results
+
=
(mean
-
i)
*
*
2
return
results
for
i
in
range
(
1
,
max
):
num_min_data
=
[]
num_max_data
=
[]
for
j
in
range
(length):
if
data[j]>i:
num_max_data.append(data[j])
else
:
num_min_data.append(data[j])
arr_var_max
=
fz(num_max_data)
arr_var_min
=
fz(num_min_data)
print
(
"----------------------------------"
)
print
(
"阈值为:"
,i)
print
(
"阈值左边值为:"
,num_min_data,
"均值:"
,myMean(num_min_data))
print
(
"阈值右边值为:"
,num_max_data,
" 均值:"
,myMean(num_max_data))
print
(
"阈值左边方差为: "
,arr_var_min)
print
(
"阈值右边方差为: "
,arr_var_max)
ratio_left
=
arr_var_min
*
len
(num_min_data)
/
length
ratio_right
=
arr_var_max
*
len
(num_max_data)
/
length
ratio_last
=
ratio_left
+
ratio_right
print
(
"方差和比例相乘为: "
,ratio_last)
if
(ratio_last<min_result):
min_result
=
ratio_last
result_threshold
=
i
print
(
"*"
*
50
)
print
(result_threshold)
print
(min_result)
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