一、函数简介
1、threshold—图像简单阈值化处理
函数原型：threshold(src, thresh, maxval, type, dst=None)
src：图像矩阵
thresh：阈值
maxVal：像素最大值
type：阈值化类型
2、adaptiveThreshold—图像自适应阈值化处理
函数原型：adaptiveThreshold(src, maxValue, adaptiveMethod, thresholdType, blockSize, C, dst=None)
src：图像矩阵
maxValue：像素最大值
adaptiveMethod：自适应方法
thresholdType：阈值化类型
blockSize：窗口尺寸
C：为一整数，减去该整数来对阈值进行微调
3、thresholding.otsu—图像最大类间方差阈值化处理
函数原型：thresholding.otsu(src)
src：图像矩阵
4、thresholding.rc—图像Riddler-Calvard阈值化处理
函数原型：thresholding.rc(src)
src：图像矩阵
二、实例演练
1、图像二值化及反转
代码如下：
<code class="hljs avrasm has-numbering" style="display: block; padding: 0px; background: transparent; color: inherit; box-sizing: border-box; font-family: "Source Code Pro", monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal;"><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#encoding:utf-8</span>
<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#</span>
<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#图像二值化及反转</span>
<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#</span>
import numpy as np
import cv2
image = cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.imread</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"H:\\img\\coins.bmp"</span>)
image = cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.cvtColor</span>(image, cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.COLOR</span>_BGR2GRAY)<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#将图像转为灰色</span>
blurred = cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.GaussianBlur</span>(image, (<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">5</span>, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">5</span>), <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>)<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#高斯滤波</span>
cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.imshow</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"Image"</span>, image)<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#显示图像</span>
(T, thresh) = cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.threshold</span>(blurred, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">155</span>, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">255</span>, cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.THRESH</span>_BINARY)<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#阈值化处理，阈值为：155</span>
cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.imshow</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"Threshold Binary"</span>, thresh)
(T, threshInv) = cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.threshold</span>(blurred, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">155</span>, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">255</span>, cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.THRESH</span>_BINARY_INV)<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#反阈值化处理，阈值为：155</span>
cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.imshow</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"Threshold Binary Inverse"</span>, threshInv)
<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#cv2.imshow("Coins", cv2.bitwise_and(image, image, mask =threshInv))</span>
cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.waitKey</span>(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>)</code><ul class="pre-numbering eye-protector-processed" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(193, 230, 198); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right: 1px solid rgba(0, 0, 0, 0.34902); list-style: none; text-align: right; transition: background 0.3s ease;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li></ul><ul class="pre-numbering eye-protector-processed" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(193, 230, 198); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right: 1px solid rgba(0, 0, 0, 0.34902); list-style: none; text-align: right; transition: background 0.3s ease;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li></ul>
结果如下：
原图像：
二值化图像：
二值化反转图像：
2、图像自适应阈值化
代码如下：
<code class="hljs avrasm has-numbering" style="display: block; padding: 0px; background: transparent; color: inherit; box-sizing: border-box; font-family: "Source Code Pro", monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal;"><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#encoding:utf-8</span>
<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#</span>
<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#自适应阈值化处理</span>
<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#</span>
import numpy as np
import cv2
image = cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.imread</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"H:\\img\\lena.jpg"</span>)<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#读取图像</span>
image = cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.cvtColor</span>(image, cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.COLOR</span>_BGR2GRAY)<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#将图像转化为灰度</span>
blurred = cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.GaussianBlur</span>(image, (<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">5</span>, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">5</span>), <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>)<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#高斯滤波</span>
cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.imshow</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"Image"</span>, image)
<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#自适应阈值化处理</span>
<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#cv2.ADAPTIVE_THRESH_MEAN_C：计算邻域均值作为阈值</span>
thresh = cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.adaptiveThreshold</span>(blurred, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">255</span>,cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.ADAPTIVE</span>_THRESH_MEAN_C, cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.THRESH</span>_BINARY_INV, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">11</span>, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">4</span>)
cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.imshow</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"Mean Thresh"</span>, thresh)
<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#cv2.ADAPTIVE_THRESH_GAUSSIAN_C：计算邻域加权平均作为阈值</span>
thresh = cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.adaptiveThreshold</span>(blurred, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">255</span>,cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.ADAPTIVE</span>_THRESH_GAUSSIAN_C, cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.THRESH</span>_BINARY_INV, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">15</span>, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">3</span>)
cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.imshow</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"Gaussian Thresh"</span>, thresh)
cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.waitKey</span>(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>)</code><ul class="pre-numbering eye-protector-processed" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(193, 230, 198); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right: 1px solid rgba(0, 0, 0, 0.34902); list-style: none; text-align: right; transition: background 0.3s ease;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li></ul><ul class="pre-numbering eye-protector-processed" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(193, 230, 198); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right: 1px solid rgba(0, 0, 0, 0.34902); list-style: none; text-align: right; transition: background 0.3s ease;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li></ul>
结果如下：
原图像：
自适应阈值—邻域均值：
自适应阈值—邻域加权平均：
3、最大类间方差阈值化
代码如下：
<code class="hljs avrasm has-numbering" style="display: block; padding: 0px; background: transparent; color: inherit; box-sizing: border-box; font-family: "Source Code Pro", monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal;"><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#encoding:utf-8</span>
<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#</span>
<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#最大类间方差法</span>
<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#</span>
import numpy as np
import cv2
import mahotas
<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#载入图像</span>
image = cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.imread</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"H:\\img\\lena.jpg"</span>) <span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#读入图像</span>
cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.imshow</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"Original"</span>,image)<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#显示原图像</span>
cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.waitKey</span>()<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#程序暂停</span>
<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#对图像进行高斯滤波</span>
image = cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.cvtColor</span>(image,cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.COLOR</span>_BGR2GRAY)<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#将原图像转化为灰度图像</span>
blurred = cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.GaussianBlur</span>(image,(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">5</span>,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">5</span>),<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>)<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#高斯滤波</span>
cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.imshow</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"Image"</span>,image)<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#显示图像</span>
cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.waitKey</span>()
<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#Otsu's threshold法</span>
T = mahotas<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.thresholding</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.otsu</span>(blurred)<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">##最大类间方差法求阈值，T为阈值</span>
print <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"Otsu's threshold:%d"</span> %(T)<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#打印阈值</span>
thresh = image<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.copy</span>()<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#复制图像:image(矩阵)</span>
thresh[thresh >T] = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">255</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#矩阵thresh中>T的值赋值为255</span>
thresh[thresh < <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">255</span>] = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#矩阵thresh中<255的值赋值为0</span>
thresh = cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.bitwise</span>_not(thresh)<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#thresh取反</span>
cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.imshow</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"Otsu"</span>,thresh)<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#显示图像</span>
cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.waitKey</span>()</code><ul class="pre-numbering eye-protector-processed" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(193, 230, 198); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right: 1px solid rgba(0, 0, 0, 0.34902); list-style: none; text-align: right; transition: background 0.3s ease;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li></ul><ul class="pre-numbering eye-protector-processed" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(193, 230, 198); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right: 1px solid rgba(0, 0, 0, 0.34902); list-style: none; text-align: right; transition: background 0.3s ease;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li></ul>
结果如下：
原图像：
最大类间方差阈值化：
4、Riddler-Calvard方法
代码如下：
<code class="hljs avrasm has-numbering" style="display: block; padding: 0px; background: transparent; color: inherit; box-sizing: border-box; font-family: "Source Code Pro", monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal;"><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#encoding:utf-8</span>
<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#</span>
<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#最大类间方差法</span>
<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#</span>
import numpy as np
import cv2
import mahotas
<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#载入图像</span>
image = cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.imread</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"H:\\img\\lena.jpg"</span>) <span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#读入图像</span>
cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.imshow</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"Original"</span>,image)<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#显示原图像</span>
cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.waitKey</span>()<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#程序暂停</span>
<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#对图像进行高斯滤波</span>
image = cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.cvtColor</span>(image,cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.COLOR</span>_BGR2GRAY)<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#将原图像转化为灰度图像</span>
blurred = cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.GaussianBlur</span>(image,(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">5</span>,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">5</span>),<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>)<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#高斯滤波</span>
cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.imshow</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"Image"</span>,image)<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#显示图像</span>
cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.waitKey</span>()
<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#Riddler-Calvard方法</span>
T = mahotas<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.thresholding</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.rc</span>(blurred)<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#用Riddler-Calvard法求阈值</span>
print <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"Riddler-Calvard:%d"</span> %(T)<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#打印阈值</span>
thresh = image<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.copy</span>()<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#复制图像:image(矩阵)</span>
thresh[thresh >T] = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">255</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#矩阵thresh中>T的值赋值为255</span>
thresh[thresh < <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">255</span>] = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#矩阵thresh中<255的值赋值为0</span>
thresh = cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.bitwise</span>_not(thresh)<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#thresh取反</span>
cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.imshow</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"Riddler-Calvard"</span>,thresh)<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#显示图像</span>
cv2<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.waitKey</span>()</code><ul class="pre-numbering eye-protector-processed" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(193, 230, 198); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right: 1px solid rgba(0, 0, 0, 0.34902); list-style: none; text-align: right; transition: background 0.3s ease;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li><li style="box-sizing: border-box; padding: 0px 5px;">30</li></ul><ul class="pre-numbering eye-protector-processed" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(193, 230, 198); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right: 1px solid rgba(0, 0, 0, 0.34902); list-style: none; text-align: right; transition: background 0.3s ease;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li><li style="box-sizing: border-box; padding: 0px 5px;">30</li></ul>
结果如下：
原图像：
Riddler-Calvard方法：
