OpenCV : convert the pointer in memory to image - c++

Question

I have a grabber which can get the images and show them on the screen with the following code
while((lastPicNr = Fg_getLastPicNumberBlockingEx(fg,lastPicNr+1,0,10,_memoryAllc))<200) {
iPtr=(unsigned char*)Fg_getImagePtrEx(fg,lastPicNr,0,_memoryAllc);
::DrawBuffer(nId,iPtr,lastPicNr,"testing"); }
but I want to use the pointer to the image data and display them with OpenCV, cause I need to do the processing on the pixels. my camera is a CCD mono camera and the depth of the pixels is 8bits. I am new to OpenCV, is there any option in opencv that can get the return of the (unsigned char*)Fg_getImagePtrEx(fg,lastPicNr,0,_memoryAllc); and disply it on the screen? or get the data from the iPtr pointer an allow me to use the image data?

Answer 1

Creating an IplImage from unsigned char* raw_data takes 2 important instructions: cvCreateImageHeader() and cvSetData():
// 1 channel for mono camera, and for RGB would be 3
int channels = 1;
IplImage* cv_image = cvCreateImageHeader(cvSize(width,height), IPL_DEPTH_8U, channels);
if (!cv_image)
{
// print error, failed to allocate image!
}
cvSetData(cv_image, raw_data, cv_image->widthStep);
cvNamedWindow("win1", CV_WINDOW_AUTOSIZE);
cvShowImage("win1", cv_image);
cvWaitKey(10);
// release resources
cvReleaseImageHeader(&cv_image);
cvDestroyWindow("win1");
I haven't tested the code, but the roadmap for the code you are looking for is there.

Answer 2

If you are using C++, I don't understand why your are not doing it the simple way like this:
If your camera is supported, I would do it this way:
cv::VideoCapture capture(0);
if(!capture.isOpened()) {
// print error
return -1;
}
cv::namedWindow("viewer");
cv::Mat frame;
while( true )
{
capture >> frame;
// ... processing here
cv::imshow("viewer", frame);
int c = cv::waitKey(10);
if( (char)c == 'c' ) { break; } // press c to quit
}
I would recommend starting to read the docs and tutorials which you can find here.