image#xff1a;二值图像#xff08;cv2.t…一、找轮廓

cv2.findContours()

cv2.findContours(image*,mode*,method*)

contours找到的所有轮廓数组数组内的元素为轮廓像素点坐标。

mode轮廓检测模式常见方法如下

模式值解释RETR_EXTERNAL0只检测外部轮廓RETR_LIST1检测所有轮廓但不建立层级关系RETR_CCOMP2检测所有轮廓同时建立两个层级关系如果内部还有轮廓则此轮廓与最外层轮廓同级RETR_TREE3检测所有轮廓同时建立一个树状层级关系

方法值解释CHAIN_APPROX_NONE1存储所有轮廓点坐标CHAIN_APPROX_SIMPLE2只保存轮廓顶点坐标CHAIN_APPROX_TC89L13使用CHAIN_APPROX_TC89L1

近视算法保存轮廓坐标CHAIN_APPROX_TC89KCOS4使用CHAIN_APPROX_TC89KCOS近视算法保存轮廓坐标

二、绘轮廓

cv2.drawContours(image*,contours,contourIdx*,color*,thickness*,lineType*,hierarchy*,maxLevel*,offset*)img目标图像。

contourscv2.findContours()函数返回的轮廓列表

thickness轮廓粗细-1

maxLevel轮廓层次关系的深度0表示绘制第0层次关系的轮廓。

三、检测模式

cv2.cvtColor(img,cv2.COLOR_BGR2GRAY)

GRAY

cv2.threshold(img_gray,150,255,cv2.THRESH_BINARY)

二值contours,hierarchy

cv2.findContours(img_threshold,cv2.RETR_EXTERNAL,cv2.CHAIN_APPROX_SIMPLE)

img1

cv2.drawContours(img,contours,-1,(255,0,0),3)cv2.imshow(img,img)

cv2.imshow(img_threshold,img_threshold)

cv2.waitKey(0)

cv2.cvtColor(img,cv2.COLOR_BGR2GRAY)

GRAY

cv2.threshold(img_gray,150,255,cv2.THRESH_BINARY)

二值contours,hierarchy

cv2.findContours(img_threshold,cv2.RETR_LIST,cv2.CHAIN_APPROX_SIMPLE)

img1

cv2.drawContours(img,contours,-1,(255,0,0),2)cv2.imshow(img,img)

cv2.imshow(img_threshold,img_threshold)

cv2.waitKey(0)

cv2.cvtColor(img,cv2.COLOR_BGR2GRAY)

GRAY

cv2.threshold(img_gray,150,255,cv2.THRESH_BINARY)

二值contours,hierarchy

cv2.findContours(img_threshold,cv2.RETR_CCOMP,cv2.CHAIN_APPROX_SIMPLE)

print(hierarchy)

cv2.drawContours(img,contours,-1,(255,0,0),2)cv2.imshow(img,img)

cv2.imshow(img_threshold,img_threshold)

cv2.waitKey(0)

hierarchy详细解释请参考《OpenCV计算机视觉项目实战Python版---p265》

print(hierarchy)结果

cv2.cvtColor(img,cv2.COLOR_BGR2GRAY)

GRAY

cv2.threshold(img_gray,150,255,cv2.THRESH_BINARY)

二值contours,hierarchy

cv2.findContours(img_threshold,cv2.RETR_TREE,cv2.CHAIN_APPROX_SIMPLE)

print(hierarchy)

cv2.drawContours(img,contours,-1,(255,0,0),2)cv2.imshow(img,img)

cv2.imshow(img_threshold,img_threshold)

cv2.waitKey(0)

hierarchy详细解释请参考《OpenCV计算机视觉项目实战Python版---p265》

print(hierarchy)

cv2.contourArea(contour*,oriented*)

import

cv2.cvtColor(img,cv2.COLOR_BGR2GRAY)

GRAY

cv2.threshold(img_gray,150,255,cv2.THRESH_BINARY)

二值contours,hierarchy

cv2.findContours(img_threshold,cv2.RETR_EXTERNAL,cv2.CHAIN_APPROX_SIMPLE)

img1

cv2.drawContours(img,contours,-1,(255,0,0),2)

areas

cv2.contourArea(contours[i])areas.append(area)

print(areas)

cv2.arcLength(contours,closed*)

import

cv2.cvtColor(img,cv2.COLOR_BGR2GRAY)

GRAY

cv2.threshold(img_gray,150,255,cv2.THRESH_BINARY)

二值contours,hierarchy

cv2.findContours(img_threshold,cv2.RETR_EXTERNAL,cv2.CHAIN_APPROX_SIMPLE)

img1

cv2.drawContours(img,contours,-1,(255,0,0),2)

areas

cv2.arcLength(contours[i],closedTrue)areas.append(arc)

print(areas)