python opencv 识别圆角矩形,OpenCV-如何找到圆角矩形的矩形轮廓？

雨点打透心脏的1/2处 2023-01-24 02:14 68阅读 0赞

![Image 1][]

I'm trying to find the contour of a rectangle object with round corner in a image. I tried HoughLinesP and findContours, but did not achieve the desired result.

![65de33bf0f33e170345b1dcc0cc22b6b.png][]

I want to find the rectangle like this:

![28d41279e1d75d8190c545278b66a48a.png][]

Code:

import cv2

import matplotlib.pyplot as plt

import util

image = cv2.imread("./img/findrect0.png", 1)

gray = util.grayImage(image)

edges = cv2.Canny(image, 50, 200)

lines = cv2.HoughLinesP(edges, 1, cv2.cv.CV\_PI/180, 50, minLineLength=50, maxLineGap=10)\[0\]

linesImage = image.copy()

util.drawLines(linesImage, lines, thickness=10)

contoursImage = image.copy()

(contours, hierarchy) = cv2.findContours(gray.copy(), cv2.RETR\_EXTERNAL, cv2.CHAIN\_APPROX\_SIMPLE)

util.drawContours(contoursImage, contours, thickness=10)

util.showOpenCVImagesGrid(\[image, edges, linesImage, contoursImage\], 2, 2, titles=\["original image", "canny image", "lines image", "contours image"\])

util:

import cv2

import math

import matplotlib.pyplot as plt

def showOpenCVImagesGrid(images, x, y, titles=None, axis="on"):

fig = plt.figure()

i = 1

for image in images:

copy = image.copy()

channel = len(copy.shape)

cmap = None

if channel == 2:

cmap = "gray"

elif channel == 3:

copy = cv2.cvtColor(copy, cv2.COLOR\_BGR2RGB)

elif channel == 4:

copy = cv2.cvtColor(copy, cv2.COLOR\_BGRA2RGBA)

fig.add\_subplot(x, y, i)

if titles is not None:

plt.title(titles\[i-1\])

plt.axis(axis)

plt.imshow(copy, cmap=cmap)

i += 1

plt.show()

def grayImage(image):

gray = cv2.cvtColor(image, cv2.COLOR\_BGR2GRAY)

return gray

def drawLines(image, lines, thickness=1):

for line in lines:

\# print("line="+str(line))

cv2.line(image, (line\[0\], line\[1\]), (line\[2\], line\[3\]),

(0, 0, 255), thickness)

def drawContours(image, contours, thickness=1):

i = 0

for contour in contours:

cv2.drawContours(image, \[contours\[i\]\], i, (0, 255, 0), thickness)

area = cv2.contourArea(contour)

i += 1

I'm using Python 2.7.13 and OpenCV 2.4.13.3.

I've been thinking to extend these lines and get intersection points of lines. Finally, I will get four coordinates of rectangle.

But if the image is more complex, I don't know how to deal with.

解决方案

You need to find the bounding rectangle of the found contours.

img = cv2.imread("image.png", -1)

gray = cv2.cvtColor(img, cv2.COLOR\_BGR2GRAY)

binary = cv2.bitwise\_not(gray)

(\_,contours,\_) = cv2.findContours(binary, cv2.RETR\_EXTERNAL, cv2.CHAIN\_APPROX\_NONE)

for contour in contours:

(x,y,w,h) = cv2.boundingRect(contour)

cv2.rectangle(img, (x,y), (x+w,y+h), (0,255,0), 2)

![d4ff05ce3a53f6d1d103222d7a5070df.png][]

[Image 1]: 
[65de33bf0f33e170345b1dcc0cc22b6b.png]: /images/20221004/f84fd558a49e4ea3887351b2ca4710ca.png
[28d41279e1d75d8190c545278b66a48a.png]: /images/20221004/cb0c298bcf404054b23ff98ae8f2cbff.png
[d4ff05ce3a53f6d1d103222d7a5070df.png]: /images/20221004/7b8a0928449842748023d988f528c2d7.png