OpenCV 交换两个颜色通道

#include 

#include 

#include 

#include 

using namespace cv;

int main(int argc, char *argv[])

{

    QCoreApplication a(argc, argv);

    QFile file("1.rgba");

    if(!file.open(QIODevice::ReadOnly))

        return -1;

    QByteArray arr = file.readAll();

    Mat ori(100, 720, CV_8UC4, arr.data());

    //Mat dest = Mat::zeros(100, 720,  CV_8UC4);

    //cvtColor(ori, dest, COLOR_RGBA2BGRA);

    QFile bgra("3A");

    bgra.open(QIODevice::WriteOnly);

    qDebug() << ori.channels();

    //channel 0 = R

    //channel 1 = G

    //channel 2 = B

    //channel 3 = A

    for(int y = 0; y < ori.rows; y++)

    {

        for(int x = 0; x < ori.cols; x++)

        {

            /*uchar rgba[4] = {0};

            rgba[0] = dest.at(y, x)[2];

            rgba[1] = dest.at(y, x)[1];

            rgba[2] = dest.at(y, x)[0];

            rgba[3] = dest.at(y, x)[3];

            bgra.write((const char*)rgba, 4);*/

            for( int c = 0; c < 4; c++)

            {

                uchar  chr = 0;

                if(c == 3)

                {

                    chr = 255;

                    bgra.write((const char*)&chr, 1);

                    continue;

                }

                bgra.write((const char*)&chr, 1);

            }

        }

    }

    bgra.close();

    qDebug() << "file generated";

    return a.exec();

}