Question

When trying to load an Image and copy a part of it or smooth, everything ok, but when I’m capturing video and try to copy a part of the frame, it becomes reverse and rotated on 180 degrees, does anybody knows why?

IplImage *scaled=cvCreateImage(sz,IPL_DEPTH_8U,3); 
capture = cvCaptureFromFile( "C:\\New York.avi" ); 
IplImage *frame = cvQueryFrame( capture ); 
cvResize(frame,scaled,CV_INTER_LINEAR); 
cvShowImage("123",scaled);
cvReleaseImage(&scaled);

Answer 1

You need to match the depth and number of channels of the destination image to make the resize operation work. Right now, you are assuming these values.

capture = cvCaptureFromFile("C:\\New York.avi"); 
IplImage* frame = cvQueryFrame(capture); 
IplImage* scaled = cvCreateImage(sz, frame->depth, frame->nChannels); 

cvResize(frame, scaled, CV_INTER_LINEAR); 
cvShowImage("123", scaled);

cvWaitKey(0); // wait for a key press, and then

cvReleaseImage(&scaled);

I hope you are using a recent version of OpenCV.

EDIT:

On a comment below you stated that you are using OpenCV b5a. I just found a message from 2006 that mentions this version, which means you are using a jurassic release of OpenCV and that’s probably the root of the problem.

There’s a page that shows how to use OpenCV with C++ Builder, but if you are having problems with that, I suggest you move to another compiler.

What you are observing is most likely a bug of this ancient release of OpenCV.