如何將int []轉換爲OpenCV Mat？ （反之亦然）

Question

我正在從PNG中讀取bufferedImages，並使用PixelGrabber將它們轉換爲int數組。我的問題是：我如何使用整數數組來製作相應的OpenCV Mat？陣列是1D，每個值代表一個像素的RGB值。

我已經嘗試過使用字節數組。

Answer 1

只是將32位int值解釋爲32位RGBA值。我不知道爲什麼你不需要改變通道的順序，但是使用int數組作爲你的cv::Mat的輸入，你會自動獲得BGRA排序。然後，如果需要，您只需刪除Alpha通道。

int main() 
{ 
    // the idea is that each int is 32 bit which is 4 channels of 8 bit color values instead of 3 channels, so assume a 4th channel. 

    // first I create fake intArray which should be replaced by your input... 
    const int imgWidth = 320; 
    const int imgHeight = 210; 
    int intArray[imgWidth*imgHeight]; // int array 

    // fill the array with some test values: 
    for(unsigned int pos = 0; pos < imgWidth*imgHeight; ++pos) 
     intArray[pos] = 8453889; // 00000000 10000000 11111111 00000001 => R = 128, G = 255, B = 1 
     //intArray[pos] = 65280; // green 
     //intArray[pos] = 16711680; // red 
     //intArray[pos] = 255; // blue 

    // test: 
    int firstVal = intArray[0]; 
    std::cout << "values: " << " int: " << firstVal << " R = " << ((firstVal >> 16) & 0xff) << " G = " << ((firstVal >> 8) & 0xff) << " B = " << (firstVal & 0xff) << std::endl; 

    // here you create the Mat and use your int array as input 
    cv::Mat intMat_BGRA = cv::Mat(imgHeight,imgWidth,CV_8UC4, intArray); 
    // now you have a 4 channel mat with each pixel is one of your int, but with wrong order... 
    std::cout << "BGRA ordering: " << intMat_BGRA.at<cv::Vec4b>(0,0) << std::endl; 
    // this is in fact the BGRA ordering but you have to remove the alpha channel to get BGR values: 
    // (unless you can live with BGRA values => you have to check whether there is garbage or 0s/255s in the byte area 

    // so split the channels... 
    std::vector<cv::Mat> BGRA_channels; 
    cv::split(intMat_BGRA, BGRA_channels); 

    // remove the alpha channel: 
    BGRA_channels.pop_back(); 

    // and merge back to image: 
    cv::Mat intMat_BGR; 
    cv::merge(BGRA_channels, intMat_BGR); 

    std::cout << "BGR ordering: " << intMat_BGR.at<cv::Vec3b>(0,0) << std::endl; 

    cv::imshow("ordereed", intMat_BGR); 

    cv::waitKey(0); 
    return 0; 
} 

給我輸出：

values: int: 8453889 R = 128 G = 255 B = 1 
BGRA ordering: [1, 255, 128, 0] 
BGR ordering: [1, 255, 128]