python opencv实现旋转矩形框裁减功能

本文实例为大家分享了python opencv实现旋转矩形框裁减的具体代码,供大家参考,具体内容如下

经常遇见旋转矩形框的裁减问题,那么思路是,将矩形框旋转正然后再裁减

# -*- coding:gb2312 -*-

import cv2

from math import *

import numpy as np

import time

def rotateImage(img,degree,pt1,pt2,pt3,pt4):

height,width=img.shape[:2]

heightNew = int(width * fabs(sin(radians(degree))) + height * fabs(cos(radians(degree))))

widthNew = int(height * fabs(sin(radians(degree))) + width * fabs(cos(radians(degree))))

matRotation=cv2.getRotationMatrix2D((width/2,height/2),degree,1)

matRotation[0, 2] += (widthNew - width) / 2

matRotation[1, 2] += (heightNew - height) / 2

imgRotation = cv2.warpAffine(img, matRotation, (widthNew, heightNew), borderValue=(255, 255, 255))

pt1 = list(pt1)

pt3 = list(pt3)

[[pt1[0]], [pt1[1]]] = np.dot(matRotation, np.array([[pt1[0]], [pt1[1]], [1]]))

[[pt3[0]], [pt3[1]]] = np.dot(matRotation, np.array([[pt3[0]], [pt3[1]], [1]]))

imgOut=imgRotation[int(pt1[1]):int(pt3[1]),int(pt1[0]):int(pt3[0])]

cv2.imshow("imgOut",imgOut) #裁减得到的旋转矩形框

cv2.imwrite("imgOut.jpg",imgOut)

# pt2 = list(pt2)

# pt4 = list(pt4)

# [[pt2[0]], [pt2[1]]] = np.dot(matRotation, np.array([[pt2[0]], [pt2[1]], [1]]))

# [[pt4[0]], [pt4[1]]] = np.dot(matRotation, np.array([[pt4[0]], [pt4[1]], [1]]))

# pt1 = (int(pt1[0]), int(pt1[1]))

# pt2 = (int(pt2[0]), int(pt2[1]))

# pt3 = (int(pt3[0]), int(pt3[1]))

# pt4 = (int(pt4[0]), int(pt4[1]))

# drawRect(imgRotation,pt1,pt2,pt3,pt4,(255,0,0),2)

return imgRotation

def drawRect(img,pt1,pt2,pt3,pt4,color,lineWidth):

cv2.line(img, pt1, pt2, color, lineWidth)

cv2.line(img, pt2, pt3, color, lineWidth)

cv2.line(img, pt3, pt4, color, lineWidth)

cv2.line(img, pt1, pt4, color, lineWidth)

if __name__=="__main__":

startTime=time.time()

imgSrc=cv2.imread('E:\桌面\lena.jpg')

imgResize=cv2.resize(imgSrc,(500,500))

pt1=(100,100)

pt2=(150,50)

pt3=(175,75)

pt4=(125,125)

# drawRect(imgResize,pt1,pt2,pt3,pt4,(0,0,255),2)

imgRotation=rotateImage(imgResize,-degrees(atan2(50,50)),pt1,pt2,pt3,pt4)

endTime = time.time()

print endTime-startTime

cv2.imshow("imgRotation",imgRotation)

cv2.imwrite("imgRotation.jpg",imgRotation)

cv2.waitKey(0)

效果图:

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