Question

I’m writing with visual c++ using opencv (2.3 version) and qt (4.8 version) and I have some problems with loading files (jpg images) from a folder and saving to another one. Here’s my code:

for (uint i = 0; i < numFiles; i += (numFiles / numBoards) ){

    QString str = "D:/TESI_Magistrale/Linescanner/imm_aquisition/image" + QString::number(i + 1) + ".jpg";
    QImage *image=new QImage();
    image->load(str);


    IplImage *currentImage = cvCreateImageHeader(cv::Size(640,480),IPL_DEPTH_8U,1);//1 channel xk b&w (solo brightness)
    currentImage->imageData = (char*)image;

    QString str1 = "D:/TESI_Magistrale/Linescanner/imm_calibration/image" + QString::number(i + 1) + ".jpg";
    QByteArray ba1 = str1.toLatin1();
    const char *text1 = ba1.data();
    cvSaveImage(text1,currentImage);


}

The problem is that when I open the jpg images in the saving folder (imm_calibration), they’re completely different from the original. Where’s the error?
Thanks in advance.

Answer 1

currentImage->imageData = (char*)image;

This is certainly really dubious. you are converting a QImage* to a char*. First thing to do is to change to

currentImage->imageData = image->bits();

in order to use the buffer.
Another thing, you are creating currentImage with fixed values, maybe it is better to use

cvCreateImageHeader(cv::Size(image->width(),image->height(),....)

This is for the qt part. It may still not be enough.