opencv Qt如何有效地创建彩色图像并将其传递给QImage？

Question

This question is partially answered at how to convert an opencv cv::Mat to qimage

I use Qt 5.5, and opencv 2.4, mac yosemite 10.10.5.

I'm looking for an efficient way to display a color image with a QImage, whose color information come from 3 distinct cv::Mat objects which contain the 3 RGB channels of a color image. For my own "education" I need to understand how to originally work with the channels separated. It is unclear to me what will be the most efficient way to end up with the QImage from these 3 separated channels.

The cv::Mat objects are declared and assigned as follows:

imRed = new Mat(Size(naxis1, naxis2), CV_64F);
imGreen = new Mat(Size(naxis1, naxis2), CV_64F);
imBlue = new Mat(Size(naxis1, naxis2), CV_64F);


double* redP = imRed->ptr<double>(0);
double* greenP = imGreen->ptr<double>(0);
double* blueP = imBlue->ptr<double>(0);

for (long i = 0; i < nPixels; i++)
{

    redP[i] = (double) rawProcess.imgdata.image[i][0];;
    greenP[i] = (double) rawProcess.imgdata.image[i][1];
    blueP[i] = (double) rawProcess.imgdata.image[i][2];

}

where rawProcess is an object from the Libraw library which contains the image data. redP , greenP , blueP are, as their name indicate, the pointer to the red, green and blue channel, and this code assumes (correct me if i'm wrong) that the cv::Mat addresses of the pixel values are continuous in memory.

From here, how shall I efficiently pass the buffer of the color image to QImage, ie, minimizing intermediate copy, loops etc... (if necessary, my system can use openMP, I have 4 threads available)?

Thanks

Answer 1

This code below is working.

Starting from the above code (with naxis1 and naxis2 the width and height of the image):

imRed = new Mat(Size(naxis1, naxis2), CV_64F);
imGreen = new Mat(Size(naxis1, naxis2), CV_64F);
imBlue = new Mat(Size(naxis1, naxis2), CV_64F);


double* redP = imRed->ptr<double>(0);
double* greenP = imGreen->ptr<double>(0);
double* blueP = imBlue->ptr<double>(0);

for (long i = 0; i < nPixels; i++)
{

    redP[i] = (double) rawProcess.imgdata.image[i][0];;
    greenP[i] = (double) rawProcess.imgdata.image[i][1];
    blueP[i] = (double) rawProcess.imgdata.image[i][2];

}

I add:

std::vector<cv::Mat> matVector;
matVector.push_back(imRed);
matVector.push_back(imGreen);
matVector.push_back(imBlue);

cv::Mat colorMat32;
cv::merge(matVector, colorMat32);

cv::Mat colorMat888

double alpha = (double) (255 / 65535);
double beta = 0.0;

colorMat32.convertTo(colorMat888, CV_8UC3, alpha, beta);

newPaintImage = new QImage(colorMat888.data, naxis1, naxis2, QImage::Format_RGB888);

Thanks @Micka.