QT实现一个图片透视变换的小玩意

近来有点烦，不想看论文，不想做项目，无聊之余把好久之前想到的用qt做一个图片透视变换的小工具的想法实现了一下。。。详细如下：

说明：对于有些平时拍的图片可能产生了透视效果，而你想得到正向拍摄的效果，你就可以根据opencv中的透视变换，选择矩形物体图片中的四个点，变换到正常图像状态，还有其他用处，自己去想吧，哈哈。

0. 首先看一下效果，有兴趣可以继续往下看,

1. 使用说明

（1）首先打开一张图片，调整需要透视变换物体在左边图形框中完全显示。

（2）点击左下角 ‘选择角点’ 按钮，然后按照顺时针顺序依次点击四个角点，点击“选择结束”，不点也没关系。

（3）输入转换后的图片高度和宽度，默认值为200，320，点击“透视变换“ 按钮即可显示变换后的图像。

（4）点击”保存图片“ 按钮，选择保存位置，输入文件名，不要忘了加后缀 ”.jpg“ 。

2.创建一个qt桌面项目，添加opencv库，pro文件如下

#-------------------------------------------------
#
# Project created by QtCreator 2019-03-04T09:22:39
#
#-------------------------------------------------QT       += core guigreaterThan(QT_MAJOR_VERSION, 4): QT += widgetsTARGET = perspective_img
TEMPLATE = app
#include opencv files
INCLUDEPATH += /usr/include \/usr/include/opencv \/usr/include/opencv2LIBS += /usr/lib/x86_64-linux-gnu/libopencv_highgui.so \/usr/lib/x86_64-linux-gnu/libopencv_core.so    \/usr/lib/x86_64-linux-gnu/libopencv_imgproc.so#作者：Shawn-HT
#来源：CSDN
#原文：https://blog.csdn.net/shawn_ht/article/details/40795039
版权声明：本文为博主原创文章，转载请附上博文链接！DEFINES += QT_DEPRECATED_WARNINGSSOURCES += \main.cpp \mainwindow.cpp
HEADERS += \mainwindow.h
FORMS += \mainwindow.ui

3. 在界面.ui文件中对需要显示的部件进行布局

4. main.cpp 文件没变，主要修改mainwindow.h 和mainwindow.cpp文件

mainwindow.h 文件如下

#ifndef MAINWINDOW_H
#define MAINWINDOW_H#include <QMainWindow>
#include <QFileDialog>
#include <opencv2/opencv.hpp>
using namespace cv;namespace Ui {
class MainWindow;
}
class QLabel;class MainWindow : public QMainWindow
{Q_OBJECTpublic:explicit MainWindow(QWidget *parent = 0);~MainWindow();void DisplayMat(cv::Mat image);void mousePressEvent(QMouseEvent *event);//void paintEvent(QPaintEvent *event);bool eventFilter(QObject *watched, QEvent *event);Mat perspectivetransfer(Mat srcImage);signals:void button_click_update();
public slots:void drawRedCircle();//void drawRedPoint(int x,int y);void on_actionAbout_triggered();void on_actionSpecifications_triggered();private slots:void on_pushButton_open_clicked();void on_pushButton_choose_clicked(bool checked);void on_pushButton_perspective_clicked();void on_pushButton_save_clicked();private:Ui::MainWindow *ui;cv::Mat image;QLabel *label;int count;//initial for corners orderint point_x = 10;int point_y = 10;Point point_lt,point_rt,point_rb,point_lb;Mat src_resize;Mat save_image;
};#endif // MAINWINDOW_H

5. mainwindow.cpp 文件如下

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <iostream>
#include <QDebug>
#include <QMessageBox>
#include <QTextCodec>
#include <QLabel>
#include <QMouseEvent>
#include <QPoint>
#include <QPainter>MainWindow::MainWindow(QWidget *parent) :QMainWindow(parent),ui(new Ui::MainWindow)
{ui->setupUi(this);setWindowTitle(tr("Image Perspective tool-2019.03.10"));label = new QLabel(ui->scrollArea);//构造函数中注册事件过滤器//ui->labelimage->installEventFilter(this);//QObject::connect(this,SIGNAL(button_click_update()),this,SLOT(drawRedCircle()));
}MainWindow::~MainWindow()
{delete ui;
}void MainWindow::on_actionAbout_triggered() {QMessageBox::about(this, tr("About ..."),tr("<h2>Image Perspective:1.0 </h2><p>Copyright 龙性的腾飞 </p>""<p>School of Electrical and Information Engineering,Tianjin University</p>"));
}void MainWindow::on_actionSpecifications_triggered() {QMessageBox::about(this, tr("Specifications"),tr("<h2>Steps as follows： </h2><p>1.Open a picture, do not contain chinese characters in the path. </p>""<p>2. Press 'Choose Corners' button and click four corners of the object you want to perspective transform in a clockwise. </p>""<p>3. Press 'Perspective Transform' button, then save the picture transformed.</p>"));
}bool MainWindow::eventFilter(QObject *watched, QEvent *event)
{if (watched == ui->labelimage && event->type() == QEvent::Paint)drawRedCircle();return QWidget::eventFilter(watched, event);}void MainWindow::drawRedCircle()
{//在label上绘制图形---->一个红色圆点QPainter painter(ui->labelimage);painter.drawLine (QPoint(0,0),QPoint(100,100));painter.setPen(Qt::NoPen);painter.setRenderHint(QPainter::Antialiasing,true);painter.setBrush(QColor(255,0,0));painter.drawLine (QPoint(0,0),QPoint(100,100));qDebug() << "left click";painter.drawEllipse(point_x,point_y,4,4);qDebug() << point_x;//update();
}void MainWindow::mousePressEvent(QMouseEvent *event)
{// 如果是鼠标左键按下//---------------------//作者：祥知道//来源：CSDN//原文：https://blog.csdn.net/humanking7/article/details/80707591//版权声明：本文为博主原创文章，转载请附上博文链接！if (event->button() == Qt::LeftButton && ui->lineEdit_LB->isEnabled()){QPoint global_pos = event->globalPos();QPoint label_pos = label->mapFromGlobal(global_pos);point_x = label_pos.x();point_y = label_pos.y();QString x = QString::number(label_pos.x(), 10);QString y = QString::number(label_pos.y(), 10);QString point = "("+x+","+y+")";if (ui->pushButton_choose->isChecked()){count += 1;update();//emit button_click_update();//drawRedPoint(point_x,point_y);switch (count) {case 1:ui->lineEdit_LT->setText(point);point_lt.x = label_pos.x();point_lt.y = label_pos.y();break;case 2:ui->lineEdit_RT->setText(point);point_rt.x = label_pos.x();point_rt.y = label_pos.y();break;case 3:ui->lineEdit_RB->setText(point);point_rb.x = label_pos.x();point_rb.y = label_pos.y();break;case 4:ui->lineEdit_LB->setText(point);point_lb.x = label_pos.x();point_lb.y = label_pos.y();break;}}//qDebug() << "left click"<<event->pos()<<"global:"<<event->globalPos()<<"label_pos:"<<label_pos;}
}void MainWindow::on_pushButton_open_clicked()
{QString filename = QFileDialog::getOpenFileName(this,tr("Open Image"),"/home/sun/",tr("Image File (*.jpg *.png *.bmp)"));qDebug()<<"filenames:"<<filename;QTextCodec *code = QTextCodec::codecForName("gb18030");std::string name = code->fromUnicode(filename).data();//filename.toAscii().data()image = cv::imread(name);QString w = QString::number(image.size().width, 10);QString h = QString::number(image.size().height, 10);QString w_h = " width: "+w+" height: "+h;//https://blog.csdn.net/ei__nino/article/details/7297791//QString s = QString::number(a, 10);             // s == "63"ui->statusBar->showMessage(filename+w_h);if(!image.data){ui->pushButton_perspective->setEnabled(false);QMessageBox msgBox;msgBox.setText(tr("Image Data Is Null"));msgBox.exec();}else {//DisplayMat(image);//https://blog.csdn.net/xiezhongyuan07/article/details/79621467//https://blog.csdn.net/qq_37233607/article/details/79082243ui->pushButton_perspective->setEnabled(true);QImage qimage(filename);int q_width = qimage.size().width();int q_height = qimage.size().height();if (q_width>640 || q_height>480 ){//label = new QLabel(ui->scrollArea);cv::resize(image,image,Size(640,q_height*640/q_width));//sr= image.resize(640);//resize(image, src_resize, Size(640,q_height*640/q_width));label->setPixmap(QPixmap::fromImage(qimage).scaled(QSize(640,q_height*640/q_width),Qt::KeepAspectRatio));label->setAlignment(Qt::AlignTop);ui->scrollArea->setWidget(label);qDebug()<<"labelsize:"<<qimage.size();}else{label = new QLabel(ui->scrollArea);label->setPixmap(QPixmap::fromImage(qimage));label->setAlignment(Qt::AlignTop);ui->scrollArea->setWidget(label);}}
}void MainWindow::DisplayMat(cv::Mat image)
{cv::Mat rgb;QImage img;if(image.channels() == 3){cvtColor(image,rgb,CV_BGR2RGB);img = QImage((const unsigned char*)(rgb.data),rgb.cols,rgb.rows,rgb.cols*rgb.channels(),//rgb.cols*rgb.channels()可以替换为image.stepQImage::Format_RGB888);}else{img = QImage((const unsigned char*)(image.data),image.cols,image.rows,rgb.cols*image.channels(),QImage::Format_RGB888);}QSize label_resize = QSize(image.size().width,image.size().height);//qDebug()<<"imagesize:"<<image.size();ui->labelimage->setPixmap(QPixmap::fromImage(img).scaled(label_resize));//setPixelmap(QPixmap::fromImage(img));ui->labelimage->resize(ui->labelimage->pixmap()->size());//resize(ui->label->pixmap()->size());//ui->scrollArea->setWidget(ui->labelimage);会出现崩溃，必须QLabel创建才可以//qDebug()<<"labelsize:"<<ui->labelimage->size();}
//---------------------
//作者：call_me_yang
//来源：CSDN
//原文：https://blog.csdn.net/yang6464158/article/details/38109415
//版权声明：本文为博主原创文章，转载请附上博文链接！void MainWindow::on_pushButton_choose_clicked(bool checked)
{if(checked){ui->pushButton_choose->setText("选择结束");count = 0;ui->lineEdit_LT->setEnabled(true);ui->lineEdit_LT->clear();ui->lineEdit_RT->setEnabled(true);ui->lineEdit_RT->clear();ui->lineEdit_RB->setEnabled(true);ui->lineEdit_RB->clear();ui->lineEdit_LB->setEnabled(true);ui->lineEdit_LB->clear();}else{ ui->pushButton_choose->setText("选择角点"); }
}
/*void MainWindow::paintEvent(QPaintEvent *)
{QPainter painter(this);qDebug()<<"labelsize";QPen pen(Qt::red,5,Qt::SolidLine,Qt::RoundCap,Qt::RoundJoin);painter.setPen(pen);painter.drawLine (QPoint(0,0),QPoint(100,100));//must use QImage
}*/
Mat MainWindow::perspectivetransfer(Mat srcImage)
{   //选择的待变换角点Point2f pts_src[] = { point_lt,point_rt,point_rb,point_lb};//透视变换后的角点int height = ui->lineEdit_height->text().toInt();int width = ui->lineEdit_width->text().toInt();Point2f pts_dst[] = {Point(10, 10),Point(10+width, 10),Point(10+width, 10+height) ,Point(10, 10+height) };Mat &&M = cv::getPerspectiveTransform(pts_src, pts_dst);Mat warp;Mat PerspectivedImg(height+20, width+20, CV_8UC1);PerspectivedImg.setTo(0);cv::warpPerspective(srcImage, warp, M, PerspectivedImg.size(), cv::INTER_LINEAR , cv::BORDER_REPLICATE);//imshow("After Perspectived", warp);return warp;
}void MainWindow::on_pushButton_perspective_clicked()
{save_image = perspectivetransfer(image);DisplayMat(save_image);
}void MainWindow::on_pushButton_save_clicked()
{QString filename =QFileDialog::getSaveFileName(this,tr("Save Image..."),"/home/sun/deeplearning",tr("Image File (*.jpg *.png *.bmp)"));qDebug()<<"filenames:"<<filename;std::string After_perspective = filename.toStdString();imwrite(After_perspective,save_image);
}

6.总结

代码都是现用现查的，相关代码来源网址已附在程序中，还有以前的一些代码稍微拼了拼就出来了，由于水平有限，代码写的不是那么规范，以及操作不当会出现崩溃情况，还大家多多交流。

代码中有关于绘图的代码没有用，我也没删除，主要是开始想在点击图片选点时没点一个点可以显示一个位置红点，无奈对paintevent理解不够，一直无法实现，没再花时间搞，对变换功能影响不大。

待我有时间把代码传到github，先留个空，有问题和想法欢迎留言交流！

https://github.com/sunyuzhe2017/Perspective