Jpg images doesn't load properly - only white background

never_ever

Hi,
I have some pairs of JPG images that I want to load. Problem is that I get only white background (no image is visible although founction load return true). First I thought that there is problem with .jpg image format plugin and I copy jpeg.dll to folder "plugins/imageformats" in my project path. But it still doesn't work.

void ImageGUI::loadImagesForStereo()
{
   QStringList imagesList1 = QFileDialog::getOpenFileNames(this, tr("Open images from left camera"), ".", tr("JPG files (*.jpg)"));
   QStringList imagesList2 = QFileDialog::getOpenFileNames(this, tr("Open images from left camera"), ".", tr("JPG files (*.jpg)"));
   if(imagesList1.size() > 0 && imagesList2.size() > 0)
     ImageClass::startOfflineCalib(imagesList1, imagesList2);
   else
   {
     QString str;
     str = tr("No images for ");
     if(imagesList1.size() <=0 && imagesList2.size() <= 0)
       str += tr("left & right view chosen");
     else if(imagesList1.size() <= 0)
       str += tr("left view chosen");
     else if(imagesList2.size() <= 0)
       str += tr("right view chosen");

     ui.teInfo->append(str);
   }
}

bool ImageClass::startOfflineCalib(QStringList imagesLeft, QStringList imagesRight)
{
  m_imageList1.clear();
  m_imageList2.clear();

  
  if(imagesLeft.size() != imagesRight.size())
    return false;

  for(int i = 0; i < imagesLeft.size(); i++)
  {
    QImage image1;
    bool success1 = image1.load(imagesLeft[i]);
    QString path = QDir::currentPath();
    QString tmpStr = imagesLeft[i];
    
   
    qDebug()<<tmpStr;

//TEST: image display
    QPixmap* pm = new QPixmap();
    qDebug()<<i<<"loaded: "<<pm->load(tmpStr, ".jpg");
    QLabel lbl;
    lbl.setPixmap(*pm);
    lbl.show();
// END TEST
   
    cv::Mat tmpMat1(image1.height(), image1.width(), CV_8UC3, (uchar*)image1.bits(),image1.bytesPerLine());
    cv::Mat imageMat1; 
    //cvtColor(tmpMat1, imageMat1,CV_BGR2RGB);
    
    QImage image2;
    bool success2 = image2.load(imagesRight[i]);
    cv::Mat tmpMat2(image2.height(), image2.width(), CV_8UC3, (uchar*)image2.bits(),image2.bytesPerLine());
    cv::Mat imageMat2; 
   // cvtColor(tmpMat2, imageMat2,CV_BGR2RGB);

    if(success1 && success2)
    {
      m_imageList1.append(imageMat1);
      m_imageList2.append(imageMat2);
    }
  }
}

Any ideas why I get only white label?

label expands to image size
image->isNull() returns false;
jpeg.dll is definitely loaded (info from visual output).
JPG images properly saves to files, I can't only load them
I add to main file QApplication::addLibraryPath("plugins/imageformats") (I don't how exactly it should looks like so I have tried also "./plugins/imageformats", "plugins/"

m.sue

Hi,
in this code you load into tmpMat* and add empty imageMat* to your list.
-Michael.

never_ever

Ok, the lines cvtColor(tmpMat1, imageMat1, CV_BGR2RGB) was commented for tests after I realized that jpg isn't loading. More important are lines of code that are higher (between TEST and END TEST comments and some lines higher), because there I try to test why it doesn't load my images.

m.sue

Can you give a link to one of these problematic jpeg images, maybe there is something special about the images.
-Michael.

never_ever

@m.sue Yes, but I can do it for 5-6 hours when I will have directly access to my computer

never_ever

@m.sue Ok I upload image to one of the host: one of the images from sequence

SGaist

Hi,

Loading your image with this quick written application works fine:

#include <QtWidgets>

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
    QLabel label;
    label.setPixmap(QPixmap("6f81f00d48.jpg"));
    label.show();
    return app.exec();
}

One thing in your code. There's no need to allocated the QPixmap on heap.

m.sue

Hi,
your image looks ok, your code looks ok (maybe write "JPG" instead of ".jpg", or just call without an image type hint). So there has to be another problem:
Does imagesLeft[i] contain an absolute path and the correct path to the image? I see that you check the directory, so maybe you already assumed something in this direction?
-Michael.

never_ever

Now it works fine (I have no idea why it didn't work earlier). However, I decided to use opencv function imread() because I must use cv::Mat later, and it is better to read it by opencv function than transform from QImage to cv::Mat

Btw I have tried to transform from QImage to cv::Mat

QImage image;
bool success = image.load(imagesRight[i]);
cv::Mat tmpMat(image.height(), image.width(), CV_8UC3, (uchar*)image.bits(),image.bytesPerLine());

but if I display that tmpMat

imshow("after", tmpMat);

I get image that has vertical strips (sth like this image after transformation

In other part of my program I acquire images from camera as IplImage. I change them to cv::Mat and then to QImage and save and it works fine. Why it doesn't work the other way?