第一个参数是图片的名称，如果是固定的，强烈建议使用/作为目录的分割符号

 第二参数具有如下的值，说明了读取过程中是否需要进行像素的操作，例如取值0，表示读取过程中将像素转换为灰度值，默认参数是1， 表示不改变原图像的像素

enum ImreadModes {

       IMREAD_UNCHANGED            = -1, //!< If set, return the loaded image as is (with alpha channel, otherwise it gets cropped).

       IMREAD_GRAYSCALE            = 0,  //!< If set, always convert image to the single channel grayscale image.

       IMREAD_COLOR                = 1,  //!< If set, always convert image to the 3 channel BGR color image.

       IMREAD_ANYDEPTH             = 2,  //!< If set, return 16-bit/32-bit image when the input has the corresponding depth, otherwise convert it to 8-bit.

       IMREAD_ANYCOLOR             = 4,  //!< If set, the image is read in any possible color format.

       IMREAD_LOAD_GDAL            = 8,  //!< If set, use the gdal driver for loading the image.

       IMREAD_REDUCED_GRAYSCALE_2  = 16, //!< If set, always convert image to the single channel grayscale image and the image size reduced 1/2.

       IMREAD_REDUCED_COLOR_2      = 17, //!< If set, always convert image to the 3 channel BGR color image and the image size reduced 1/2.

       IMREAD_REDUCED_GRAYSCALE_4  = 32, //!< If set, always convert image to the single channel grayscale image and the image size reduced 1/4.

       IMREAD_REDUCED_COLOR_4      = 33, //!< If set, always convert image to the 3 channel BGR color image and the image size reduced 1/4.

       IMREAD_REDUCED_GRAYSCALE_8  = 64, //!< If set, always convert image to the single channel grayscale image and the image size reduced 1/8.

       IMREAD_REDUCED_COLOR_8      = 65, //!< If set, 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.

     };

注意：

在进行图像的灰度值处理之后，默认情况下， 不会进行图像的直方图进行图像的增强，否则会出现运行异常

代码

#include <opencv2/highgui/highgui.hpp>    

#include <opencv2/imgproc/imgproc.hpp>

#include <iostream>

using namespace cv;

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

{

  Mat image = imread("D:/20170601092226.png", 0);

  if (image.empty())

  {

    std::cout << "打开图片失败,请检查" << std::endl;

    return -1;

  }

  imshow("原图像", image);

  waitKey();

  return 0;

  Mat imageRGB[3];

  split(image, imageRGB);

  for (int i = 0; i < 3; i++)

  {

    equalizeHist(imageRGB[i], imageRGB[i]);

  }

  merge(imageRGB, 3, image);

  imshow("直方图均衡化图像增强效果", image);

  waitKey();

  return 0;

}