I have QWidget (named as screenshotLabel) and continuously it's content is changing.I can get that lable content to qpixmap (named as originalPixmap) as bellow.
originalPixmap = QPixmap();
QPixmap pixmap(screenshotLabel->size());
this->render(&pixmap);
originalPixmap = pixmap;
Now I want to save it as a video file.But I could not able to do it.How can I save QWidget content as a video file?
I found a way to generate video using OpenCV VideoWriter.I leave comments in the code that describe what is happening.
originalPixmap = pixmap;
qImageSingle = originalPixmap.toImage(); // Convert QPixmap to QImage
// Get QImage data to Open-cv Mat
frame = Mat(qImageSingle.height(), qImageSingle.width(), CV_8UC3, qImageSingle.bits(), qImageSingle.bytesPerLine()).clone();
namedWindow("MyVideo", CV_WINDOW_AUTOSIZE);
imshow("MyVideo", frame);
vector<int> compression_params;
compression_params.push_back(CV_IMWRITE_PNG_COMPRESSION);
compression_params.push_back(9);
try {
imwrite("alpha2.png", frame, compression_params);
VideoWriter video("out2.avi", CV_FOURCC('M','J','P','G'), 10, Size(qImageSingle.width(), qImageSingle.height()), true);
for(int i=0; i<100; i++){
video.write(frame); // Write frame to VideoWriter
}
}
catch (runtime_error& ex) {
fprintf(stderr, "Exception converting image to PNG format: %s\n", ex.what());
}
Related
I made an Image Editor in Qt / OpenCV where you can load the Image from the File explorer and grayscale/adaptive threshold/resize it afterwards.
Bug 1: When I resize the Loaded Image to (for example) 600x600 Pixels using my ImageProcessor::Resize(int, int) method, it works fine. But when I change it to like 546x750 Pixels, the Image has a weird grayscale.
Bug 2: When I want to resize my Grayscaled/Thresholded Image, it always gets a weird grayscale similiar to Bug 1.
Codes:
mainwindow.cpp
#include "mainwindow.h"
#include "ui_mainwindow.h"
#include "resizer.h"
MainWindow::MainWindow(QWidget *parent)
: QMainWindow(parent)
, ui(new Ui::MainWindow)
{
ui->setupUi(this);
}
MainWindow::~MainWindow()
{
delete ui;
}
void MainWindow::Display(cv::Mat inputImage)
{
QImage image = QImage(inputImage.data, inputImage.cols, inputImage.rows, QImage::Format_RGB888);
scene->addPixmap(QPixmap::fromImage(image));
ui->graphicsView->setScene(scene);
ui->graphicsView->show();
}
void MainWindow::on_actionOpen_triggered()
{
QString file = QFileDialog::getOpenFileName(this, "Open", "", "Images (*.jpg *.png)");
std::string filename = file.toStdString();
inputImage = cv::imread(filename);
Display(inputImage);
imgProc = new ImageProcessor(inputImage);
}
void MainWindow::on_pushButton_clicked() // Grayscale
{
scene->clear();
imgProc->mode = 1;
inputImage = imgProc->Grayscale();
QImage image = QImage(inputImage.data, inputImage.cols, inputImage.rows, QImage::Format_Grayscale8);
scene->addPixmap(QPixmap::fromImage(image));
ui->graphicsView->setScene(scene);
ui->graphicsView->show();
}
void MainWindow::on_pushButton_2_clicked() // ADT
{
scene->clear();
imgProc->mode = 2;
inputImage = imgProc->AdaptiveThreshold();
QImage image = QImage(inputImage.data, inputImage.cols, inputImage.rows, QImage::Format_Grayscale8);
scene->addPixmap(QPixmap::fromImage(image));
ui->graphicsView->setScene(scene);
ui->graphicsView->show();
}
void MainWindow::on_pushButton_3_clicked() // Resize
{
scene->clear();
Resizer resizer;
resizer.exec();
int newWidth = resizer.GetWidth();
int newHeight = resizer.GetHeight();
inputImage = imgProc->Resize(newWidth, newHeight);
if(imgProc->mode == 1 || imgProc->mode == 2)
{
QImage image = QImage(inputImage.data, inputImage.cols, inputImage.rows, QImage::Format_Grayscale8);
scene->addPixmap(QPixmap::fromImage(image));
ui->graphicsView->setScene(scene);
ui->graphicsView->show();
}
else
{
QImage image = QImage(inputImage.data, inputImage.cols, inputImage.rows, QImage::Format_RGB888);
scene->addPixmap(QPixmap::fromImage(image));
ui->graphicsView->setScene(scene);
ui->graphicsView->show();
}
}
imageprocessor.cpp
#include "imageprocessor.h"
ImageProcessor::ImageProcessor(cv::Mat inputImage)
{
this->inputImage = inputImage;
}
cv::Mat ImageProcessor::Resize(int width, int height)
{
cv::Mat resized;
cv::resize(inputImage, resized, cv::Size(width, height), cv::INTER_LINEAR);
return resized;
}
cv::Mat ImageProcessor::Grayscale()
{
cv::Mat grayscaled;
cv::cvtColor(inputImage, grayscaled, cv::COLOR_RGB2GRAY);
return grayscaled;
}
cv::Mat ImageProcessor::AdaptiveThreshold()
{
cv::Mat binarized, grayscaled;
cv::cvtColor(inputImage, grayscaled, cv::COLOR_RGB2GRAY);
cv::adaptiveThreshold(grayscaled, binarized, 255, cv::ADAPTIVE_THRESH_GAUSSIAN_C, cv::THRESH_BINARY, 15, 11);
return binarized;
}
QImage::Format_RGB888 is the format type you defined means that:
The image is stored using a 24-bit RGB format (8-8-8).
If your image has 3 channels then your way is correct to continue, except adding this:
QImage image = QImage(inputImage.data, inputImage.cols, inputImage.rows, QImage::Format_RGB888).rgbSwapped();
You need to add at the end rgbSwapped() because Qt reads it in RGB order as OpenCV gives BGR.
If you want to send a gray scale image to GUI then you need to use QImage::Format_Grayscale8 format type, which means:
The image is stored using an 8-bit grayscale format.
Here is the clear cocumentation for the formats.
Note: How do you resize your image, by using OpenCV function ? Share resizer.h , I will update the answer accordingly.
I have started learning Qt and is trying to make a simple video Player which will load the video and will play it. It worked perfectly fine. Now added thresholding functionality to it. The threshold value will be obtained from the spinBox.
Code is written in such a way that thresholding operation will be done with value in spinBox except at value 0 (where normal video is displayed).
So this is my function for the same:
void Player::run()
{
while(!stop )
{
if(!capture.read(frame))
stop = true;
// convert RGB to gray
if(frame.channels() == 3)
{
if(thresh == 0)
{
cvtColor(frame, RGBframe, CV_BGR2RGB);
img = QImage((const unsigned char*)(RGBframe.data),
RGBframe.cols,RGBframe.rows,QImage::Format_RGB888);
}
else
{
Mat temp;
cvtColor(frame, temp, CV_BGR2GRAY);
threshold(temp, binary, thresh, 255, 0);
img = QImage((const unsigned char*)(binary.data),
binary.cols, binary.rows, QImage::Format_Indexed8);
bool save = img.save("/home/user/binary.png");
cout<<"threshold value = "<<thresh<<endl;
//imshow("Binary", binary);
}
}
else
{
if(thresh == 0) // original Image
{
img = QImage((const unsigned char*)(frame.data),
frame.cols,frame.rows,QImage::Format_Indexed8);
}
else // convert to Binary Image
{
threshold(frame, binary, thresh, 255, 0);
img = QImage((const unsigned char*)(binary.data),
binary.cols, binary.rows, QImage::Format_Indexed8);
}
}
emit processedImage(img);
this->msleep(delay);
}
}
for spinBox value equals 0 it runs fine but when spinBox value is incremented I get only black screen. I tried imshow(cv:: Mat binary)and it is showing the correct binary image but when I try to save QImage img it is some random black and white pixels (though of same size of original frame).
It seems that you're missing the color table for your indexed image. You need to add a color table (before the while loop):
QVector<QRgb> sColorTable(256);
for (int i = 0; i < 256; ++i){ sColorTable[i] = qRgb(i, i, i); }
and after you create the QImage from the binary Mat you need to add
img.setColorTable(sColorTable);
Or, as pointed out by #KubaOber, from Qt 5.5 you can also use the format QImage::Format_Grayscale8:
// From Qt 5.5
QImage image(inMat.data, inMat.cols, inMat.rows,
static_cast<int>(inMat.step),
QImage::Format_Grayscale8);
In general, you can wrap all Mat to QImage conversion in a function. Below there is the bug corrected and updated version of cvMatToQImage originally found here.
You can then remove all the conversion to QImage from your code and use this function instead.
QImage cvMatToQImage(const cv::Mat &inMat)
{
switch (inMat.type())
{
// 8-bit, 4 channel
case CV_8UC4:
{
QImage image(inMat.data,
inMat.cols, inMat.rows,
static_cast<int>(inMat.step),
QImage::Format_ARGB32);
return image;
}
// 8-bit, 3 channel
case CV_8UC3:
{
QImage image(inMat.data,
inMat.cols, inMat.rows,
static_cast<int>(inMat.step),
QImage::Format_RGB888);
return image.rgbSwapped();
}
// 8-bit, 1 channel
case CV_8UC1:
{
#if QT_VERSION >= 0x050500
// From Qt 5.5
QImage image(inMat.data, inMat.cols, inMat.rows,
static_cast<int>(inMat.step),
QImage::Format_Grayscale8);
#else
static QVector<QRgb> sColorTable;
// only create our color table the first time
if (sColorTable.isEmpty())
{
sColorTable.resize(256);
for (int i = 0; i < 256; ++i)
{
sColorTable[i] = qRgb(i, i, i);
}
}
QImage image(inMat.data,
inMat.cols, inMat.rows,
static_cast<int>(inMat.step),
QImage::Format_Indexed8);
image.setColorTable(sColorTable);
#endif
}
default:
qWarning() << "cvMatToQImage() - cv::Mat image type not handled in switch:" << inMat.type();
break;
}
return QImage();
}
I'm capturing webcam streams from two raspberry pis and I'm trying to carry out some image processing on both streams. I have two Qlabels I'm trying to use to display the images from the pis. However, whilst one stream displays in real time, the other has a 4-5 second delay. The same result occurs if I try to display one stream on both Qlabel objects. Is this a threading issue? Can you guys please help out?
VideoCapture capWebcam;
VideoCapture EyeintheSky;
Mat matEyeInTheSky;
QImage qimgEyeInTheSky;
Mat matOriginal;
QImage qimgOriginal;
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
capWebcam.open("http://192.168.0.102:8080/?action=stream?dummy=param.mjpg"); //from MJPG STreamer image processing
EyeintheSky.open("http://192.168.0.100:8080/?action=stream?dummy=param.mjpg");
if (capWebcam.isOpened() == false) {
return;
}
if(EyeintheSky.isOpened() == false) {
return;
}
}
void MainWindow::processFrameAndUpdateGUI() {
capWebcam.read(matOriginal);
EyeintheSky.read(matEyeInTheSky);
if(matOriginal.empty() == true) {
qDebug() << "Empty Picture";
return;
}
else {
// start of visual processing
// Output Tri Track images to screen
// map QImage to QLabel
cvtColor(matOriginal,matOriginal,COLOR_BGR2RGB);
QImage qimgOriginal((uchar*)matOriginal.data,matOriginal.cols,matOriginal.rows, matOriginal.step,QImage::Format_RGB888);
ui->lblInputImage->setPixmap(QPixmap::fromImage(qimgOriginal));
// Output Eye in the Sky to screen
// map QImage to QLabel
cvtColor(matEyeInTheSky, matEyeInTheSky, COLOR_BGR2RGB);
QImage qimgEyeInTheSky((uchar*)matEyeInTheSky.data, matEyeInTheSky.cols, matEyeInTheSky.rows, matEyeInTheSky.step, QImage::Format_RGB888);
ui->sky_input->setPixmap(QPixmap::fromImage(qimgEyeInTheSky));
// Process IK code.
}
}
I am trying to use this code for background subtraction for a live camera feed. but this code is giving a white image in both the windows. the problem is that when tested with a video file from the same camera it is working fine, without any error but when the video file is replaced by a camera feed it becomes white and in the running window terminal it displays error as:
HIGHGUI ERROR: V4L2: Unable to get property (1) - Invalid
argument
The above error is continuously being repeated when the video is taken from camera feed. Please help to solve this problem.
#include <opencv2/core/core.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/video/background_segm.hpp>
#include <cv.h>
#include <iostream>
#include <sstream>
using namespace cv;
using namespace std;
Mat frame; //current frame
Mat fgMaskMOG; //fg mask generated by MOG method
Mat fgMaskMOG2; //fg mask fg mask generated by MOG2 method
Ptr<BackgroundSubtractor> pMOG; //MOG Background subtractor
Ptr<BackgroundSubtractor> pMOG2; //MOG2 Background subtractor
int keyboard;
int main()
{
//create GUI windows
namedWindow("Frame",0);
//namedWindow("FG Mask MOG",0);
namedWindow("FG Mask MOG 2",0);
namedWindow("eroded",0);
namedWindow("eroded2",0);
//create Background Subtractor objects
pMOG= new BackgroundSubtractorMOG(); //MOG approach
pMOG2 = new BackgroundSubtractorMOG2(); //MOG2 approach
//create the capture object
VideoCapture capture(0);
//read input data. ESC or 'q' for quitting
while( (char)keyboard != 'q' && (char)keyboard != 27 )
{
//read the current frame
if(!capture.read(frame))
{
cerr << "Unable to read next frame." << endl;
cerr << "Exiting..." << endl;
exit(EXIT_FAILURE);
}
//update the background model
//AND HERE!!!
//pMOG->operator()(frame, fgMaskMOG);
pMOG2->operator()(frame, fgMaskMOG2);
//get the frame number and write it on the current frame
stringstream ss;
rectangle(frame, cv::Point(10, 2), cv::Point(100,20),
cv::Scalar(255,255,255), -1);
ss << capture.get(CV_CAP_PROP_POS_FRAMES);
string frameNumberString = ss.str();
putText(frame, frameNumberString.c_str(), cv::Point(15, 15),
FONT_HERSHEY_SIMPLEX, 0.5 , cv::Scalar(0,0,0));
//show the current frame and the fg masks
imshow("Frame", frame);
imshow("FG Mask MOG", fgMaskMOG);
imshow("FG Mask MOG 2", fgMaskMOG2);
//get the input from the keyboard
keyboard = waitKey( 30 );
}
//delete capture object
capture.release();
//destroy GUI windows
distroyAllWindows();
return EXIT_SUCCESS;
}
I think property
CV_CAP_PROP_POS_FRAMES
not valid for camera.
I have created a very simple UI using Qt which consists of a simple button and a label. When the button's clicked() signal is emitted, a function which captures a frame from a webcam using OpenCV is called. The code I am currently using to achieve this is:
cv::Mat MainWindow::captureFrame(int width, int height)
{
//sets the width and height of the frame to be captured
webcam.set(CV_CAP_PROP_FRAME_WIDTH, width);
webcam.set(CV_CAP_PROP_FRAME_HEIGHT, height);
//determine whether or not the webcam video stream was successfully initialized
if(!webcam.isOpened())
{
qDebug() << "Camera initialization failed.";
}
//attempts to grab a frame from the webcam
if (!webcam.grab()) {
qDebug() << "Failed to capture frame.";
}
//attempts to read the grabbed frame and stores it in frame
if (!webcam.read(frame)) {
qDebug() << "Failed to read data from captured frame.";
}
return frame;
}
After a frame has been captured, it must be converted into a QImage in order to be displayed in the label. In order to achieve this, I use the following method:
QImage MainWindow::getQImageFromFrame(cv::Mat frame) {
//converts the color model of the image from RGB to BGR because OpenCV uses BGR
cv::cvtColor(frame, frame, CV_RGB2BGR);
return QImage((uchar*) (frame.data), frame.cols, frame.rows, frame.step, QImage::Format_RGB888);
}
The constructor for my MainWaindow class looks like this:
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
resize(1280, 720);
move(QPoint(200, 200));
webcam.open(0);
fps = 1000/25;
qTimer = new QTimer(this);
qTimer->setInterval(fps);
connect(qTimer, SIGNAL(timeout()), this, SLOT(displayFrame()));
}
The QTimer is supposed to display a frame by calling dislayFrame()
void MainWindow::displayFrame() {
//capture a frame from the webcam
frame = captureFrame(640, 360);
image = getQImageFromFrame(frame);
//set the image of the label to be the captured frame and resize the label appropriately
ui->label->setPixmap(QPixmap::fromImage(image));
ui->label->resize(ui->label->pixmap()->size());
}
each time its timeout() signal is emitted.
However, while this appears to work to a degree, what actually happens is that the video capture stream from my webcam (a Logitech Quickcam Pro 9000) repeatedly opens and closes. This is evidenced by the fact that the blue ring, which indicates that the webcam is on, repeatedly flashes on and off. This leads to the refresh rate for the webcam video stream label to be very low, and is not desirable. Is there some way to make it so that the webcam stream remains open in order to prevent this "flickering" from occurring?
I seem to have solved the problem of the webcam stream opening and closing by removing the lines:
webcam.set(CV_CAP_PROP_FRAME_WIDTH, width);
webcam.set(CV_CAP_PROP_FRAME_HEIGHT, height);
from the captureFrame() function and setting the width and height of the frame to be captured in the MainWindow constructor.