python+opencv图片旋转矩形分割

待我称王封你为后i 2022-06-05 08:36 272阅读 0赞

有时候需要对有角度的矩形框内图像从原图片中分割出来。这里的程序思想是，先将图片进行矩形角度的旋转，使有角度的矩形处于水平状态后，根据原来坐标分割图片。  
参考：[http://blog.csdn.net/yjl9122/article/details/71217872][http_blog.csdn.net_yjl9122_article_details_71217872]  
修改原来的程序：

> 1.旋转函数的输入仅为矩形的四点坐标  
> 2.角度由公式计算出来  
> 3.矩形四点pt1,pt2,pt3,pt4由txt文件读入  
> 4.在旋转程序中还处理了顺时针和逆时针及出现矩形框翻转的问题。

# -*- coding:utf-8 -*-
    import cv2
    from math import *
    import numpy as np
    import time,math
    import os
    import re
    
    '''旋转图像并剪裁'''
    def rotate(
            img,  # 图片
            pt1, pt2, pt3, pt4
    ):
        print pt1,pt2,pt3,pt4
        withRect = math.sqrt((pt4[0] - pt1[0]) ** 2 + (pt4[1] - pt1[1]) ** 2)  # 矩形框的宽度
        heightRect = math.sqrt((pt1[0] - pt2[0]) ** 2 + (pt1[1] - pt2[1]) **2)
        print withRect,heightRect
        angle = acos((pt4[0] - pt1[0]) / withRect) * (180 / math.pi)  # 矩形框旋转角度
        print angle
    
        if pt4[1]>pt1[1]:
            print "顺时针旋转"
        else:
            print "逆时针旋转"
            angle=-angle
    
        height = img.shape[0]  # 原始图像高度
        width = img.shape[1]   # 原始图像宽度
        rotateMat = cv2.getRotationMatrix2D((width / 2, height / 2), angle, 1)  # 按angle角度旋转图像
        heightNew = int(width * fabs(sin(radians(angle))) + height * fabs(cos(radians(angle))))
        widthNew = int(height * fabs(sin(radians(angle))) + width * fabs(cos(radians(angle))))
    
        rotateMat[0, 2] += (widthNew - width) / 2
        rotateMat[1, 2] += (heightNew - height) / 2
        imgRotation = cv2.warpAffine(img, rotateMat, (widthNew, heightNew), borderValue=(255, 255, 255))
        cv2.imshow('rotateImg2',  imgRotation)
        cv2.waitKey(0)
    
        # 旋转后图像的四点坐标
        [[pt1[0]], [pt1[1]]] = np.dot(rotateMat, np.array([[pt1[0]], [pt1[1]], [1]]))
        [[pt3[0]], [pt3[1]]] = np.dot(rotateMat, np.array([[pt3[0]], [pt3[1]], [1]]))
        [[pt2[0]], [pt2[1]]] = np.dot(rotateMat, np.array([[pt2[0]], [pt2[1]], [1]]))
        [[pt4[0]], [pt4[1]]] = np.dot(rotateMat, np.array([[pt4[0]], [pt4[1]], [1]]))
    
        # 处理反转的情况
        if pt2[1]>pt4[1]:
            pt2[1],pt4[1]=pt4[1],pt2[1]
        if pt1[0]>pt3[0]:
            pt1[0],pt3[0]=pt3[0],pt1[0]
    
        imgOut = imgRotation[int(pt2[1]):int(pt4[1]), int(pt1[0]):int(pt3[0])]
        cv2.imshow("imgOut", imgOut)  # 裁减得到的旋转矩形框
        cv2.waitKey(0)
        return imgRotation  # rotated image
    
    
    ＃　根据四点画原矩形
    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)
    
    #　读出文件中的坐标值
    def ReadTxt(directory,imageName,last):
        fileTxt=directory+"//rawLabel//"+imageName[:7]+last  # txt文件名
        getTxt=open(fileTxt, 'r')  # 打开txt文件
        lines = getTxt.readlines()
        length=len(lines)
        for i in range(0,length,4):
            pt2=list(map(float,lines[i].split(' ')[:2]))
            pt1=list(map(float,lines[i+1].split(' ')[:2]))
            pt4=list(map(float,lines[i+2].split(' ')[:2]))
            pt3=list(map(float,re.split('\n| ',lines[i+3])[:2]))
            # float转int 
    
            pt2=list(map(int,pt2))
            pt1=list(map(int,pt1))
            pt4=list(map(int,pt4))
            pt3=list(map(int,pt3))
    
            imgSrc = cv2.imread(imageName)
            drawRect(imgSrc, tuple(pt1),tuple(pt2),tuple(pt3),tuple(pt4), (0, 0, 255), 2)
            cv2.imshow("img", imgSrc)
            cv2.waitKey(0)
            rotate(imgSrc,pt1,pt2,pt3,pt4)
    
    
    if __name__=="__main__":
        directory = "G://grasp//grapCode//trainImage//jpg//4"
        last = 'cneg.txt'
        imageName="pcd0247r.png"
        ReadTxt(directory,imageName,last)

**原带角度的矩形框：**  
![这里写图片描述][SouthEast]

**旋转矩形框：**  
![这里写图片描述][SouthEast 1]

**分割：**  
![这里写图片描述][SouthEast 2]

[http_blog.csdn.net_yjl9122_article_details_71217872]: http://blog.csdn.net/yjl9122/article/details/71217872
[SouthEast]: /images/20220605/b18dd104e87143ebbe688829790ba216.png
[SouthEast 1]: /images/20220605/55f6cd48b88f4944a4da5dfdb57722cd.png
[SouthEast 2]: /images/20220605/ab388798c48c4a97a5aef86c0efa0ec5.png