opencv C++图像读取

发布时间：2020-12-16 09:16:40 所属栏目：百科来源：网络整理

导读：int main(){ cv::Mat img =cv::imread( " /home/nan/图片/highdeepth/starry.jpg " ,cv::IMREAD_REDUCED_COLOR_8); // imread( const String filename,int flags = IMREAD_COLOR ); if (img.empty()) return - 1 ; cv::imshow( " BGR " ,img); std::vector c

int main(){
    cv::Mat img=cv::imread("/home/nan/图片/highdeepth/starry.jpg",cv::IMREAD_REDUCED_COLOR_8);
     // imread( const String& filename,int flags = IMREAD_COLOR );
    if(img.empty()) return -1;
    cv::imshow("BGR",img);
    std::vector<cv::Mat> planes;
    cv::split(img,planes);
    cv::imshow("B",planes[0]);
    cv::imshow("G",planes[1]);
    cv::imshow("R",planes[2]);
    cv::imshow("BGR",img);

    img=cv::imread("/home/nan/图片/highdeepth/starry.jpg",cv::IMREAD_REDUCED_GRAYSCALE_8);
    cv::split(img,planes);  // 灰度图只能分离出一个通道
    cv::imshow("Gray",planes[0]);
    cv::waitKey(0);
    return 0;
}

注意：如果图像像素过大，并且要读出全部图像的话可以使用尺寸缩减如：cv::IMREAD_REDUCED_COLOR_8。

flags包括以下内容：

　　　　IMREAD_UNCHANGED            = -1,//!< If set,return the loaded image as is (with alpha channel,otherwise it gets cropped).
       IMREAD_GRAYSCALE            = 0,always convert image to the single channel grayscale image.
       IMREAD_COLOR                = 1,always convert image to the 3 channel BGR color image.
       IMREAD_ANYDEPTH             = 2,return 16-bit/32-bit image when the input has the corresponding depth,otherwise convert it to 8-bit.
       IMREAD_ANYCOLOR             = 4,the image is read in any possible color format.
       IMREAD_LOAD_GDAL            = 8,use the gdal driver for loading the image.
       IMREAD_REDUCED_GRAYSCALE_2  = 16,always convert image to the single channel grayscale image and the image size reduced 1/2.
       IMREAD_REDUCED_COLOR_2      = 17,always convert image to the 3 channel BGR color image and the image size reduced 1/2.
       IMREAD_REDUCED_GRAYSCALE_4  = 32,always convert image to the single channel grayscale image and the image size reduced 1/4.
       IMREAD_REDUCED_COLOR_4      = 33,always convert image to the 3 channel BGR color image and the image size reduced 1/4.
       IMREAD_REDUCED_GRAYSCALE_8  = 64,always convert image to the single channel grayscale image and the image size reduced 1/8.
       IMREAD_REDUCED_COLOR_8      = 65,always convert image to the 3 channel BGR color image and the image size reduced 1/8.
       IMREAD_IGNORE_ORIENTATION   = 128 //!< If set,do not rotate the image according to EXIF‘s orientation flag.

（编辑：李大同）

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