When I convert a QImage to cv::Mat the Mat comes out blurred.
This is the code that converts it:
QPixmap pixmap(*ui->imgLabel->pixmap());
QImage image = pixmap.toImage();
image.convertToFormat(QImage::Format_RGB888);
Mat matImage = Mat(image.height(), image.width(), CV_8UC3, image.scanLine(0));
This is the original image zoomed:
This is the image created:
Grateful for any help.
I don't know QT, but have you tried ready solutions from WEB? For example, from this link I found another method of conversion:
Mat qimage2mat(const QImage& qimage) {
cv::Mat mat = cv::Mat(qimage.height(), qimage.width(), CV_8UC4, (uchar*)qimage.bits(), qimage.bytesPerLine());
cv::Mat mat2 = cv::Mat(mat.rows, mat.cols, CV_8UC3 );
int from_to[] = { 0,0, 1,1, 2,2 };
cv::mixChannels( &mat, 1, &mat2, 1, from_to, 3 );
return mat2;
};
Related
I'm working with OpenCV for a while and experiment with the DNN extension. My model has the input shape [1, 3, 224, 244] with pixel-depth uint8. So I put my m_inputImg which has 3-channels and 8 bit pixel depth in the function:
cv::dnn::blobFromImage(m_inputImg, m_inputImgTensor, 1.0, cv::Size(), cv::Scalar(), false, false, CV_8U);
Now I'm interested in having a Idea how my input image "lay" inside the cv::Mat tensor. Theoretically I know how the tensor looks like, but I don't understand how OpenCV do it. So to understand this I want to extract one colour channel. I've tried this:
cv::Mat blueImg = cv::Mat(cp->getModelConfigs().model[0].input.height,
cp->getModelConfigs().model[0].input.width,
CV_8UC3,
blob.ptr<uint8_t>(0, 0);
But what I get is something like that (see picture). I'm realy confused about that, can anybody help or has a good advice?
Thanks
cv::Size() will use the original image size. You are interpreting the data wrong. Here are 4 ways to interpret a 512x512 (cv::Size()) loaded blob-start from the lenna image:
input (512x512):
blob-start as a 512x512 single channel image:
blob-start as a 512x512 BGR image:
blob-start as a 224x224 BGR image:
blob-start as a 224x224 single channel:
here's the code:
int main()
{
cv::Mat img = cv::imread("C:/data/Lenna.png"); // 8UC3
cv::imshow("img", img);
cv::Mat blob;
cv::dnn::blobFromImage(img, blob, 1.0, cv::Size(), cv::Scalar(), false, false, CV_8U);
cv::Mat redImg = cv::Mat(img.rows,
img.cols,
CV_8UC1,
blob.ptr<uint8_t>(0, 0));
cv::imshow("blob 1", redImg);
cv::imwrite("red1.jpg", redImg);
cv::Mat redImg3C = cv::Mat(img.rows,
img.cols,
CV_8UC3,
blob.ptr<uint8_t>(0, 0));
cv::imshow("redImg3C", redImg3C);
cv::imwrite("red3C.jpg", redImg3C);
cv::Mat redImg224_3C = cv::Mat(224,
224,
CV_8UC3,
blob.ptr<uint8_t>(0, 0));
cv::imshow("redImg224_3C", redImg224_3C);
cv::imwrite("redImg224_3C.jpg", redImg224_3C);
cv::Mat redImg224_1C = cv::Mat(224,
224,
CV_8UC1,
blob.ptr<uint8_t>(0, 0));
cv::imshow("redImg224_1C", redImg224_1C);
cv::imwrite("redImg224_1C.jpg", redImg224_1C);
cv::waitKey(0);
}
Imho you have to do in your code:
cv::dnn::blobFromImage(m_inputImg, blob, 1.0, cv::Size(), cv::Scalar(), false, false, CV_8U);
cv::Mat blueImg = cv::Mat(m_inputImg.rows,
m_inputImg.cols,
CV_8UC3,
blob.ptr<uint8_t>(0, 0);
OR
cv::dnn::blobFromImage(m_inputImg, blob, 1.0, cv::Size(cp->getModelConfigs().model[0].input.width , cp->getModelConfigs().model[0].input.height), cv::Scalar(), false, false, CV_8U);
cv::Mat blueImg = cv::Mat(cp->getModelConfigs().model[0].input.height,
cp->getModelConfigs().model[0].input.width,
CV_8UC3,
blob.ptr<uint8_t>(0, 0);
In addition, here's the version of setting the spatial blob image size to a fixed size (e.g. the desired DNN input size):
cv::Mat blob2;
cv::dnn::blobFromImage(img, blob2, 1.0, cv::Size(224,224), cv::Scalar(), false, false, CV_8U);
cv::Mat blueImg224_1C = cv::Mat(224,
224,
CV_8UC1,
blob2.ptr<uint8_t>(0, 0));
cv::imshow("blueImg224_1C", blueImg224_1C);
cv::imwrite("blueImg224_1C.jpg", blueImg224_1C);
Giving this image:
void Qtexample::on_pushButton_clicked()
{
QString img_path = QFileDialog::getOpenFileName(this, "Select your image", QDir::homePath());
img = imread(img_path.toStdString().c_str());
Size size(200, 200);
cv::resize(img, img,size);
cvtColor(img, img, COLOR_RGB2BGR); //convering the image to RGB for QImage to handle well
QImage Qimg((uchar*)img.data, img.cols, img.rows, img.step, QImage::Format_RGB888); // converting Mat image to QImage
ui.label->setPixmap(QPixmap::fromImage(Qimg,Qt::AutoColor).scaled(ui.label->width(), ui.label->height())); // displaying the image inside the QLabel with the help of QPixmap
// imshow("image", img); // show image
}
the code works by converting a Mat image to QImage but the resulted Image is distorted a little and I need help on it.
i want to convert an image from cvMat type to Qimage , with my actual code the application does not work; i have did it the other way (Qimage to Mat it work fine)
please tell me what is going on wrong with my code
here is my code for Qimage to Mat :
Mat qimage2mat(const QImage& qimage) {
cv::Mat mat = cv::Mat(qimage.height(), qimage.width(), CV_8UC4, (uchar*)qimage.bits(), qimage.bytesPerLine());
cv::Mat mat2 = cv::Mat(mat.rows, mat.cols, CV_8UC3 );
int from_to[] = { 0,0, 1,1, 2,2 };
cv::mixChannels( &mat, 1, &mat2, 1, from_to, 3 );
return mat2;
}
and here is my code for Mat to Qimage
QImage mat2qimage(const Mat& mat) {
Mat rgb;
cvtColor(mat, rgb, CV_BGR2RGB);
return QImage((const unsigned char*)(rgb.data), rgb.cols, rgb.rows, QImage::Format_RGB888);
}
thank you by advance
as #SpamBot mentioned, the data is freed when Mat goes out of scope. try deep copying the data:
QImage mat2qimage(const Mat& mat)
{
Mat rgb;
cvtColor(mat, rgb, CV_BGR2RGB);
return QImage((const unsigned char*)(rgb.data), rgb.cols, rgb.rows, QImage::Format_RGB888).copy();
}
I want to convert an image from Mat type in OpenCV that has floating-point values into a QImage.
I did it the other way (from QImage to Mat), and here is my code :
Mat qimage2mat(const QImage& qimage) {
cv::Mat mat = cv::Mat(qimage.height(), qimage.width(), CV_8UC4, (uchar*)qimage.bits(), qimage.bytesPerLine());
cv::Mat mat2 = cv::Mat(mat.rows, mat.cols, CV_8UC3 );
int from_to[] = { 0,0, 1,1, 2,2 };
cv::mixChannels( &mat, 1, &mat2, 1, from_to, 3 );
return mat2;
}
How can I do it from Mat to QImage ?
I hope you could help me.
I' m using QT and try to do a simple detection of edges on a image. But my program crash when i launch
cv::GaussianBlur( src, src, cv::Size(3,3), 0, 0, cv::BORDER_DEFAULT );
or
cv::Sobel( src_gray, grad_x, ddepth, 1, 0, 3, scale, delta, cv::BORDER_DEFAULT );
here is my code:
QImage *image1;
IplImage *cv_image1;
image1 = new QImage("./image.png"); // Format is ARGB32
cv_image1 = QImage2IplImage(image1);
cv::Mat src(cv_image1);
cv::imshow(window_name, src); // Work Well
cv::Mat src_gray;
int scale = 1;
int delta = 0;
int ddepth = CV_16S;
cv::GaussianBlur(src, src, cv::Size(3,3), 0, 0, cv::BORDER_DEFAULT); //Crash Here
cv::imshow( window_name, src);
I think that was a problem of format.
But in another program with QIMAGES in ARGB32 this code work well.
Thank you.
Try going with proper QImage to cv::Mat conversion using this functions and you should be fine (I also included a conversion from cv::Mat to QImage):
cv::Mat cvmat_from_qimage(const QImage& qimage)
{
cv::Mat mat = cv::Mat(qimage.height(), qimage.width(), CV_8UC4, (uchar*)qimage.bits(), qimage.bytesPerLine());
cv::Mat mat2 = cv::Mat(mat.rows, mat.cols, CV_8UC3 );
int from_to[] = { 0,0, 1,1, 2,2 };
cv::mixChannels( &mat, 1, &mat2, 1, from_to, 3 );
return mat2;
}
QImage qimage_from_cvmat(const cv::Mat& mat)
{
cv::Mat rgb;
cvtColor(mat, rgb, CV_BGR2RGB);
return QImage((const unsigned char*)(rgb.data), rgb.cols, rgb.rows, QImage::Format_RGB888);
}
I Found a solution.
That' s weird but when I do:
cvtColor(src, src_gray, CV_RGB2GRAY );
cv::Sobel(src_gray, grad_x, ddepth, 1, 0, 3, scale, delta, cv::BORDER_CONSTANT);
without the cv::GaussianBlur it works well. I just change the last parameter to cv::BORDER_CONSTANT