Question

I have an problem freeing up memory allocated for an IplImage.I have given a similar situation as in my application below.(it reflects the same bug occurs in my application.)

But instead of the line

char* originalData=loadedImage->imageData;

I get my “originalData” from a QT QImage class.
Code crashes at the line where I free “image_gray”.

cvReleaseImage(&img_gray); // <-- crashes

Error message –

OpenCV Error: Assertion failed (udata < (uchar*)ptr && ((uchar*)ptr –
udata) <= (ptrdiff_t)(sizeof(void*)+16)) in fastFree, file
C:\opt\OpenCV-2.2.0\modules\co e\src\alloc.cpp, line 76 terminate
called after throwing an instance of ‘cv::Exception’ what():
C:\opt\OpenCV-2.2.0\modules\core\src\alloc.cpp:76: error: (-215) uda a
< (uchar*)ptr && ((uchar*)ptr – udata) <=
(ptrdiff_t)(sizeof(void*)+16) in fu ction fastFree

But if I use cvReleaseImageHeader() instead, if works fine but leaving a memory leak.

Any suggestions please?

void test2( char *imageFileName)
{



    IplImage *loadedImage=cvLoadImage(imageFileName);

    int xsize=loadedImage->width;
    int ysize=loadedImage->height;
    int totalBytes=xsize*ysize;


    //In my application this "originalData" data comes from a QT QImage.
    char* originalData=loadedImage->imageData;
    unsigned char* datacopy = new unsigned char [totalBytes];

    memcpy(datacopy, originalData, totalBytes);

    IplImage* img_gray = cvCreateImage( cvSize(xsize, ysize), IPL_DEPTH_8U, 1 );
    IplImage* img_gray_copy = cvCreateImage( cvSize(xsize, ysize), IPL_DEPTH_8U, 1 );
    IplImage* img_edge = cvCreateImage( cvSize(xsize, ysize), IPL_DEPTH_8U, 1 );

    IplImage* img_mask = cvCreateImage(cvSize(xsize, ysize), IPL_DEPTH_8U, 1);

    cvSet(img_mask, cvScalar(255));
    cvSet(img_gray_copy, cvScalar(255));

    cvSetZero(img_mask);


    cvSetData(img_gray, datacopy, xsize);


    cvCopy(img_gray, img_gray_copy, img_mask);

    //cvThreshold(img_gray_copy, img_edge, threshold, 255, CV_THRESH_BINARY_INV);
    //cvFindContours(img_edge, storage, contours, sizeof(CvContour), CV_RETR_TREE, CV_CHAIN_APPROX_SIMPLE);




    cvReleaseImage(&img_gray); /// <--- this crashes the application
    //cvReleaseImageHeader(&img_gray); //<--- this works.but leaving a memory leak ???
    cvReleaseImage(&img_gray_copy);

    cvReleaseImage(&img_edge);
    cvReleaseImage(&img_mask);



}

Answer 1

Ok found the issue.
I should have used cvCreateImageHeader() for img_gray .And then manually delete allocated memory.