【存档】QT和OpenCV

Qt开发的程序一般都要借助qmake生成makefile文件。因此为了加入opencv库就要修改.pro文件，下面是Linux下该文件的配置。(增加的部分)

INCLUDEPATH += . /usr/local/include/opencv
LIBS += /usr/local/lib/libcv.so /
        /usr/local/lib/libcvaux.so /
        /usr/local/lib/libcxcore.so /
        /usr/local/lib/libhighgui.so /
        /usr/local/lib/libml.so

Opencv中通过摄像头捕捉到的每帧图像的数据结构是IplImage类型的，要把它显示到Qt窗口中就需要把它转化为QImage类型的图像。

#include <QVector>
#include <cstring>

QImage MyThread::IplImageToQImage(const IplImage * iplImage,double mini, double maxi)
...{
    uchar *qImageBuffer = NULL;

        int width = iplImage->width;

/**//* Note here that OpenCV image is stored so that each lined is
32-bits aligned thus
* explaining the necessity to "skip" the few last bytes of each
line of OpenCV image buffer.
*/
        int widthStep = iplImage->widthStep;
        int height = iplImage->height;

        switch (iplImage->depth)
        ...{
            case IPL_DEPTH_8U:
            if(iplImage->nChannels == 1)
            ...{
            /**//* OpenCV image is stored with one byte grey pixel. We convert it
            to an 8 bit depth QImage.
            */
   
                qImageBuffer = (uchar *) malloc(width*height*sizeof(uchar));
                uchar *QImagePtr = qImageBuffer;
                const uchar *iplImagePtr = (const uchar *) iplImage->imageData;
   
                for(int y = 0; y < height; y++)
                ...{
                    // Copy line by line
                        memcpy(QImagePtr, iplImagePtr, width);
                        QImagePtr += width;
                        iplImagePtr += widthStep;
                }
   
            }
            else if(iplImage->nChannels == 3)
            ...{
                    /**//* OpenCV image is stored with 3 byte color pixels (3 channels).
                    We convert it to a 32 bit depth QImage.
                    */
                    qImageBuffer = (uchar *) malloc(width*height*4*sizeof(uchar));
                    uchar *QImagePtr = qImageBuffer;
                    const uchar *iplImagePtr = (const uchar *) iplImage->imageData;
                    for(int y = 0; y < height; y++)
                    ...{
                        for (int x = 0; x < width; x++)
                        ...{
                                // We cannot help but copy manually.
                                QImagePtr[0] = iplImagePtr[0];
                                QImagePtr[1] = iplImagePtr[1];
                                QImagePtr[2] = iplImagePtr[2];
                                QImagePtr[3] = 0;
       
                                QImagePtr += 4;
                                iplImagePtr += 3;
                        }
                        iplImagePtr += widthStep-3*width;
                    }    
   
            }
            else
            ...{
                    qDebug("IplImageToQImage: image format is not supported : depth=8U and %d channels ", iplImage->nChannels);
            }
            break;
            case IPL_DEPTH_16U:
            if(iplImage->nChannels == 1)
            ...{
            /**//* OpenCV image is stored with 2 bytes grey pixel. We convert it
            to an 8 bit depth QImage.
            */
                    qImageBuffer = (uchar *) malloc(width*height*sizeof(uchar));
                    uchar *QImagePtr = qImageBuffer;
                    //const uint16_t *iplImagePtr = (const uint16_t *);
            const unsigned int *iplImagePtr = (const unsigned int *)iplImage->imageData;
                    for (int y = 0; y < height; y++)
                    ...{
                        for (int x = 0; x < width; x++)
                        ...{
                        // We take only the highest part of the 16 bit value. It is
                        //similar to dividing by 256.
                            *QImagePtr++ = ((*iplImagePtr++) >> 8);
                        }
                        iplImagePtr += widthStep/sizeof(unsigned int)-width;
                    }
            }
            else
            ...{
                    qDebug("IplImageToQImage: image format is not supported : depth=16U and %d channels ", iplImage->nChannels);
   
            }
            break;
            case IPL_DEPTH_32F:
             if(iplImage->nChannels == 1)
             ...{
            /**//* OpenCV image is stored with float (4 bytes) grey pixel. We
            convert it to an 8 bit depth QImage.
            */
                     qImageBuffer = (uchar *) malloc(width*height*sizeof(uchar));
                     uchar *QImagePtr = qImageBuffer;
                     const float *iplImagePtr = (const float *) iplImage->imageData;
                     for(int y = 0; y < height; y++)
                     ...{
                         for(int x = 0; x < width; x++)
                         ...{
                                 uchar p;
                                 float pf = 255 * ((*iplImagePtr++) - mini) / (maxi - mini);
                                 if(pf < 0) p = 0;
                                 else if(pf > 255) p = 255;
                                 else p = (uchar) pf;
   
                                 *QImagePtr++ = p;
                          }
                         iplImagePtr += widthStep/sizeof(float)-width;
                     }
             }
             else
             ...{
                     qDebug("IplImageToQImage: image format is not supported : depth=32F and %d channels ", iplImage->nChannels);
             }    
               break;
               case IPL_DEPTH_64F:
             if(iplImage->nChannels == 1)
             ...{
                /**//* OpenCV image is stored with double (8 bytes) grey pixel. We
                convert it to an 8 bit depth QImage.
                */
                    qImageBuffer = (uchar *) malloc(width*height*sizeof(uchar));
                    uchar *QImagePtr = qImageBuffer;
                    const double *iplImagePtr = (const double *) iplImage->imageData;
                    for(int y = 0; y < height; y++)
                    ...{
                        for(int x = 0; x < width; x++)
                        ...{
                                uchar p;
                                double pf = 255 * ((*iplImagePtr++) - mini) / (maxi - mini);
   
                                if(pf < 0) p = 0;
                                else if(pf > 255) p = 255;
                                else p = (uchar) pf;
   
                                *QImagePtr++ = p;
                        }
                        iplImagePtr += widthStep/sizeof(double)-width;
                    }
            }
            else
            ...{
                    qDebug("IplImageToQImage: image format is not supported : depth=64F and %d channels ", iplImage->nChannels);
            }
            break;
            default:
                qDebug("IplImageToQImage: image format is not supported : depth=%d and %d channels ", iplImage->depth, iplImage->nChannels);
        }

        QImage qImage;
        QVector<QRgb> vcolorTable;
        if(iplImage->nChannels == 1)
        ...{
            // We should check who is going to destroy this allocation.
            QRgb *colorTable = new QRgb[256];
            for(int i = 0; i < 256; i++)
            ...{
                   colorTable[i] = qRgb(i, i, i);
                   vcolorTable[i] = colorTable[i];
            }
            qImage = QImage(qImageBuffer, width, height, QImage::Format_Indexed8).copy();
            qImage.setColorTable(vcolorTable);
        }
        else
        ...{
            qImage = QImage(qImageBuffer, width, height, QImage::Format_RGB32).copy();
        }
    free(qImageBuffer);
    return qImage;
}

于是你可以下面的代码(部分)测试一下：摄像头获取每一帧IplImage*类型的图像，转化为QImage类型的图像，用update()发出一个paintEvent(QPaintEvent*)事件，如此不断更新图像。(IplImageToQImage中的mini和maxi默认初始化为0)

void ImageViewer::paintEvent(QPaintEvent *)...{
    QPainter painter(this);
    painter.drawImage(QPoint(0,0), *image);
}

bool ImageViewer::ShowImage()...{
    IplImage *pImage = NULL;
    CvCapture *pCapture = NULL;
    if((pCapture = cvCaptureFromCAM(-1)) == NULL)...{
        cout << "Open camera failed! ";
        return false;
    }
    while((pImage = cvQueryFrame(pCapture)) != NULL)...{
        image = IplImageToQImage(pImage);
        update();
    }
    cvReleaseImage(&pImage);
    cvReleaseCapture(&pCapture);
    return true;
}