[c++] Converting cv::Mat to IplImage*

The documentation on this seems incredibly spotty.

I've basically got an empty array of IplImage*s (IplImage** imageArray) and I'm calling a function to import an array of cv::Mats - I want to convert my cv::Mat into an IplImage* so I can copy it into the array.

Currently I'm trying this:

while(loop over cv::Mat array)
{
    IplImage* xyz = &(IplImage(array[i]));
    cvCopy(iplimagearray[i], xyz);
}

Which generates a segfault.

Also trying:

while(loop over cv::Mat array)
{
    IplImage* xyz;
    xyz = &array[i];
    cvCopy(iplimagearray[i], xyz);
}

Which gives me a compile time error of: error: cannot convert ‘cv::Mat*’ to ‘IplImage*’ in assignment

Stuck as to how I can go further and would appreciate some advice :)

One problem might be: when using external ipl and defining HAVE_IPL in your project, the ctor

_IplImage::_IplImage(const cv::Mat& m)
{
    CV_Assert( m.dims <= 2 );
    cvInitImageHeader(this, m.size(), cvIplDepth(m.flags), m.channels());
    cvSetData(this, m.data, (int)m.step[0]);
}

found in ../OpenCV/modules/core/src/matrix.cpp is not used/instanciated and conversion fails.

You may reimplement it in a way similar to :

IplImage& FromMat(IplImage& img, const cv::Mat& m)
{
    CV_Assert(m.dims <= 2);
    cvInitImageHeader(&img, m.size(), cvIplDepth(m.flags), m.channels());
    cvSetData(&img, m.data, (int)m.step[0]);
    return img;
}

IplImage img;
FromMat(img,myMat);

According to OpenCV cheat-sheet this can be done as follows:

IplImage* oldC0 = cvCreateImage(cvSize(320,240),16,1);
Mat newC = cvarrToMat(oldC0);

The cv::cvarrToMat function takes care of the conversion issues.

Personaly I think it's not the problem caused by type casting but a buffer overflow problem; it is this line

cvCopy(iplimagearray[i], xyz);   

that I think will cause segment fault, I suggest that you confirm the array iplimagearray[i] have enough size of buffer to receive copyed data

Here is the recent fix for dlib users link

cv::Mat img = ...
IplImage iplImage = cvIplImage(img);

 (you have cv::Mat old)
 IplImage copy = old;
 IplImage* new_image = ©

you work with new as an originally declared IplImage*.

In case of gray image, I am using this function and it works fine! however you must take care about the function features ;)

CvMat * src=  cvCreateMat(300,300,CV_32FC1);      
IplImage *dist= cvCreateImage(cvGetSize(dist),IPL_DEPTH_32F,3);

cvConvertScale(src, dist, 1, 0);

Mat image1;
IplImage* image2=cvCloneImage(&(IplImage)image1);

Guess this will do the job.

Edit: If you face compilation errors, try this way:

cv::Mat image1;
IplImage* image2;
image2 = cvCreateImage(cvSize(image1.cols,image1.rows),8,3);
IplImage ipltemp=image1;
cvCopy(&ipltemp,image2);