cvSaveImage的第三个参数

http://stackoverflow.com/questions/801054/opencv-cvsaveimage-jpeg-compression-factor

  #define CV_IMWRITE_JPEG_QUALITY 1
  #define CV_IMWRITE_PNG_COMPRESSION 16
  #define CV_IMWRITE_PXM_BINARY 32

  /* save image to file */
  CVAPI(int) cvSaveImage( const char* filename, const CvArr* image, const int* params CV_DEFAULT(0) );


  int p[3];
  p[0] = CV_IMWRITE_JPEG_QUALITY;
  p[1] = desired_quality_value;
  p[2] = 0;


#include <opencv2opencv.hpp>  
#include<iostream>
#include <stdio.h>
using namespace cv;

int main(int argc, char **argv)
{
    int p[3];
    IplImage *img = cvLoadImage("test.jpg");

    p[0] = CV_IMWRITE_JPEG_QUALITY;
    p[1] = 10;
    p[2] = 0;

    cvSaveImage("out1.jpg", img, p);

    p[0] = CV_IMWRITE_JPEG_QUALITY;
    p[1] = 100;
    p[2] = 0;

    cvSaveImage("out2.jpg", img, p);

    exit(0);
}