本文实例为大家分享了python opencv实现图像目标的外接图形,供大家参考,具体内容如下
当使用cv2.findContours函数找到图像中的目标后,我们通常希望使用一个集合区域将图像包围起来,这里介绍opencv几种几何包围图形。
- 边界矩形
- 最小外接矩形
- 最小外接圆
简介
无论使用哪种几何外接方法,都需要先进行轮廓检测。
当我们得到轮廓对象后,可以使用boundingRect()得到包裹此轮廓的最小正矩形,minAreaRect()得到包裹轮廓的最小矩形(允许矩阵倾斜),minEnclosingCircle()得到包裹此轮廓的最小圆形。
最小正矩形和最小外接矩形的区别如下图所示:
实现
这里给出上述5中外接图形在python opencv上的实现:
①. 边界矩形
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import cv2 import numpy as np img = cv2.imread( '/home/pzs/图片/test.jpg' ) gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY) thresh, binary = cv2.threshold(gray, 180 , 255 , cv2.THRESH_BINARY_INV) binary, contours, hierarchy = cv2.findContours(binary, cv2.RETR_TREE, cv2.CHAIN_APPROX_NONE) cv2.imshow( 'binary' , binary) cv2.waitKey( 0 ) for cnt in contours: x,y,w,h = cv2.boundingRect(cnt) cv2.rectangle(img, (x, y), (x + w, y + h), ( 0 , 255 , 0 ), 1 ) cv2.imshow( 'image' , img) cv2.waitKey( 0 ) |
②. 最小外接矩形
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import cv2 import numpy as np img = cv2.imread( '/home/pzs/图片/test.jpg' ) gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY) thresh, binary = cv2.threshold(gray, 180 , 255 , cv2.THRESH_BINARY_INV) binary, contours, hierarchy = cv2.findContours(binary, cv2.RETR_TREE, cv2.CHAIN_APPROX_NONE) cv2.imshow( 'binary' , binary) cv2.waitKey( 0 ) for cnt in contours: rect = cv2.minAreaRect(cnt) box = cv2.boxPoints(rect) box = np.int0(box) cv2.drawContours(img, [box], 0 , ( 0 , 0 , 255 ), 2 ) cv2.imshow( 'image' , img) cv2.waitKey( 0 ) |
③. 最小外接圆
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import cv2 import numpy as np img = cv2.imread( '/home/pzs/图片/test.jpg' ) gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY) thresh, binary = cv2.threshold(gray, 180 , 255 , cv2.THRESH_BINARY_INV) binary, contours, hierarchy = cv2.findContours(binary, cv2.RETR_TREE, cv2.CHAIN_APPROX_NONE) cv2.imshow( 'binary' , binary) cv2.waitKey( 0 ) for cnt in contours: (x, y), radius = cv2.minEnclosingCircle(cnt) center = ( int (x), int (y)) radius = int (radius) cv2.circle(img, center, radius, ( 255 , 0 , 0 ), 2 ) cv2.imshow( 'image' , img) cv2.waitKey( 0 ) |
以上就是本文的全部内容,希望对大家的学习有所帮助,也希望大家多多支持服务器之家。
原文链接:https://blog.csdn.net/HUXINY/article/details/89329307