在Qt中用OpenCV2透過Webcam拍照

最近在練習使用OpenCV，順手紀錄一些用法。下面這段code可以用來控制電腦上的webcam進行拍照並且轉換成QImage物件，以便後續的使用。

#include <opencv2/opencv.hpp>

CvCapture *camera;
IplImage *frame;

camera = cvCreateCameraCapture(-1);  

/* We need to call cvRetrieveFrame twice here to get the last frame.
 * TODO: figure out the root cause and use correct method instead of
 *       the workaround.
 */
cvGrabFrame(camera);
frame = cvRetrieveFrame(camera);
frame = cvRetrieveFrame(camera);
if (frame)
{
QImage image(reinterpret_cast(frame->imageData),
frame->width, frame->height,
frame->widthStep, QImage::Format_RGB888);
QImage colorCorrectedImage(image.rgbSwapped());

/* Show colorCorrectedImage which contains the picture. */
...
}

cvReleaseCapture(&camera);