Opencv C++ to C interface function conversion - c++

Question

void doCorrectIntensityVariation(Mat& image)
{
Mat kernel = getStructuringElement(MORPH_ELLIPSE, Size(19,19));
Mat closed;
morphologyEx(image, closed, MORPH_CLOSE, kernel);
image.convertTo(image, CV_32F); // divide requires floating-point
divide(image, closed, image, 1, CV_32F);
normalize(image, image, 0, 255, NORM_MINMAX);
image.convertTo(image, CV_8UC1); // convert back to unsigned int
}
inline void correctIntensityVariation(IplImage *img)
{
//Mat imgMat(img); copy the img
Mat imgMat;
imgMat = img; //no copy is done, imgMat is a header of img
doCorrectIntensityVariation(imgMat);
imshow("gamma corrected",imgMat); cvWaitKey(0);
}
When I call
cvShowImage ("normal", n_im); cvWaitKey (0);
correctIntensityVariation(n_im);//here n_im is IplImage*
cvShowImage ("After processed", n_im); cvWaitKey (0);
// here I require n_im for further processing
I wanted "After processed" to be same as that of "gamma corrected" but what I found "After processed" was not the same as that of "gamma corrected" but same as that of "normal" . Why?? What is going wrong??

Answer 1

A very simple wrapper should do the job
Cheetsheet of openCV
I rarely use the old api, because Mat are much more easier to deal with, and
they do not have performance penalty when compare with the old c api.Like the openCV
tutorial page say The main downside of the C++ interface is that many embedded development systems at the moment support only C. Therefore, unless you are targeting embedded platforms, there’s no point to using the old methods (unless you’re a masochist programmer and you’re asking for trouble).
openCV tutorial
cv::Mat to Ipl
Ipl to cv::Mat and Mat to Ipl
IplImage* pImg = cvLoadImage(“lena.jpg”);
cv::Mat img(pImg,0); //transform Ipl to Mat, 0 means do not copy
IplImage qImg; //not pointer, it is impossible to overload the operator of raw pointer
qImg = IplImage(img); //transform Mat to Ipl
Edit : I did a mistake earlier, if the Mat would be reallocated in the function, you need
to copy or try to steal the resource(I don't know how to do it yet) from the Mat.
Copy the data
void doCorrectIntensityVariation(cv::Mat& image)
{
cv::Mat kernel = cv::getStructuringElement(cv::MORPH_ELLIPSE, cv::Size(19,19));
cv::Mat closed;
cv::morphologyEx(image, closed, cv::MORPH_CLOSE, kernel);
image.convertTo(image, CV_32F); // divide requires floating-point
cv::divide(image, closed, image, 1, CV_32F);
cv::normalize(image, image, 0, 255, cv::NORM_MINMAX);
image.convertTo(image, CV_8UC1); // convert back to unsigned int
}
//don't need to change the name of the function, the compiler treat
//these as different function in c++
void doCorrectIntensityVariation(IplImage **img)
{
cv::Mat imgMat;
imgMat = *img; //no copy is done, imgMat is a header of img
doCorrectIntensityVariation(imgMat);
IplImage* old = *img;
IplImage src = imgMat;
*img = cvCloneImage(&src);
cvReleaseImage(&old);
}
int main()
{
std::string const name = "onebit_31.png";
cv::Mat mat = cv::imread(name);
if(mat.data){
doCorrectIntensityVariation(mat);
cv::imshow("gamma corrected mat",mat);
cv::waitKey();
}
IplImage* templat = cvLoadImage(name.c_str(), 1);
if(templat){
doCorrectIntensityVariation(&templat);
cvShowImage("mainWin", templat);
// wait for a key
cvWaitKey(0);
cvReleaseImage(&templat);
}
return 0;
}
you could write a small function to alleviate the chores
void copy_mat_Ipl(cv::Mat const &src, IplImage **dst)
{
IplImage* old = *dst;
IplImage temp_src = src;
*dst = cvCloneImage(&temp_src);
cvReleaseImage(&old);
}
and call it in the function
void doCorrectIntensityVariation(IplImage **img)
{
cv::Mat imgMat;
imgMat = *img; //no copy is done, imgMat is a header of img
doCorrectIntensityVariation(imgMat);
copy_mat_to_Ipl(imgMat, img);
}
I will post how to "steal" the resource from Mat rather than copy after
I figure out a solid solution.Anyone know how to do it?