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I'm trying to perform an RGB Color mixing operation in opencv. I have the image contained in an MxNx3 Mat. I would like to multiple this with a 3x3 matrix. In Matlab I do the following: *Flatten the image from MxNx3 to a MNx3 *multiply the MNx3 matrix by the 3x3 color mixing matrix *reshape back to a MxNx3

In Opencv I would like to do the following:

void RGBMixing::mixColors(Mat &imData, Mat &rgbMixData)
{
   float rgbmix[] = {1.4237, -0.12364, -0.30003, -0.65221, 2.1936, -0.54141, -0.38854, -0.47458, 1.8631};
   Mat rgbMixMat(3, 3, CV_32F, rgbmix);
   // Scale the coefficents
   multiply(rgbMixMat, 1, rgbMixMat, 256);
   Mat temp = imData.reshape(0, 1);
   temp = temp.t();
   multiply(temp, rgbMixMat, rgbMixData);
}

This compiles but generates an exception:

OpenCV Error: Sizes of input arguments do not match (The operation is neither 'a rray op array' (where arrays have the same size and the same number of channels) , nor 'array op scalar', nor 'scalar op array') in arithm_op, file C:/slave/WinI nstallerMegaPack/src/opencv/modules/core/src/arithm.cpp, line 1253 terminate called after throwing an instance of 'cv::Exception'
what(): C:/slave/WinInstallerMegaPack/src/opencv/modules/core/src/arithm.cpp: 1253: error: (-209) The operation is neither 'array op array' (where arrays have the same size and the same number of channels), nor 'array op scalar', nor 'sca lar op array' in function arithm_op

This application has requested the Runtime to terminate it in an unusual way. Please contact the application's support team for more information.

Update 1:

This is code that appears to work:

void RGBMixing::mixColors(Mat &imData, Mat&rgbMixData)
{
    Size tempSize;
    uint32_t channels;

    float rgbmix[] = {1.4237, -0.12364, -0.30003, -0.65221, 2.1936, -0.54141, -0.38854, -0.47458, 1.8631};
    Mat rgbMixMat(3, 3, CV_32F, rgbmix);
    Mat flatImage = imData.reshape(1, 3);
    tempSize = flatImage.size();
    channels = flatImage.channels();
    cout << "temp channels: " << channels << " Size: " << tempSize.width << " x " << tempSize.height << endl;
    Mat flatFloatImage;
    flatImage.convertTo(flatFloatImage, CV_32F);
    Mat mixedImage = flatFloatImage.t() * rgbMixMat;
    mixedImage = mixedImage.t();
    rgbMixData = mixedImage.reshape(3, 1944);
    channels = rgbMixData.channels();
    tempSize = rgbMixData.size();
    cout << "temp channels: " << channels << " Size: " << tempSize.width << " x " << tempSize.height << endl;
}

But the resulting image is distorted. If I skip the multiplication of the two matrices and just assign 

mixedImage = flatFloatImage

The resulting image looks fine (just not color mixed). So I must be doing something wrong, but am getting close.

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1 に答える 1

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ここでいくつかのことがわかります：

  1. 係数をスケーリングするために、OpenCV はスカラーによる乗算をサポートしているため、代わりにmultiply(rgbMixMat, 1, rgbMixMat, 256);直接行う必要がありますrgbMixMat = 256 * rgbMixMat;。

  2. それがすべてのコードである場合、適切に初期化または値を割り当てていないimDataため、回線Mat temp = imData.reshape(0, 1);がクラッシュする可能性があります。

  3. それimDataが MxNx3 (3 チャネルのマ​​ット) であると仮定すると、それを MNx3 (1 チャネル) に再形成する必要があります。documentationによると、あなたが書いているときMat temp = imData.reshape(0, 1);は、チャンネルの数を同じままにし、行を1にする必要があると言っています。代わりに、次のようにする必要があります。

    Mat myData = Mat::ones(100, 100, CV_32FC3); // 100x100x3 matrix

    Mat myDataReshaped = myData.reshape(1, myData.rows*myData.cols); // 10000x3 matrix

  4. なぜ転置するのtemp = temp.t();ですか？

  5. あなたが書くときmultiply(temp, rgbMixMat, mixData);、これは要素ごとの製品です。行列積が必要なので、実行するだけですmixData = myDataReshaped * rgbMixMat;(そして、それを再形成します)。

編集：転置を使用しないとクラッシュしますimData.reshape(1, 3);。imData.reshape(1, imData.rows);

試す

void RGBMixing::mixColors(Mat &imData, Mat&rgbMixData)
{
    Size tempSize;
    uint32_t channels;

    float rgbmix[] = {1.4237, -0.12364, -0.30003, -0.65221, 2.1936, -0.54141, -0.38854, -0.47458, 1.8631};
    Mat rgbMixMat(3, 3, CV_32F, rgbmix);

    Mat flatImage = imData.reshape(1, imData.rows*imData.cols);
    Mat flatFloatImage;
    flatImage.convertTo(flatFloatImage, CV_32F);

    Mat mixedImage = flatFloatImage * rgbMixMat;

    rgbMixData = mixedImage.reshape(3, imData.rows); 
}
于 2012-10-01T17:58:06.270 に答える