之前用opencv仅限于在caffe代码里面调用，今天需要写个测试程序才发现编译需要一点技巧，参考http://www.cnblogs.com/woshijpf/p/3840530.html。
加上-L是因为找不到报错：“/usr/bin/ld: cannot find -lcufft”, 在这里http://blog.sciencenet.cn/blog-1583812-841855.html找到了答案
g++ opencv_imshow.cpp -o imshow -L /usr/local/cuda/lib64/ `pkg-config --cflags --libs opencv`
以下代码是为了测试opencv的resize函数的输出
//jin: compare output of imresize by opencv and by the version of Boss
//20160401 14:16
#include <stdio.h>
#include <opencv2/core/core.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/imgproc/imgproc.hpp>
#include <iostream>
using namespace std;
using namespace cv;
int bilinear_image_resize(const unsigned char *src, int width, int height,
unsigned char *dst, int nw, int nh)
{
double dx, dy, x, y;
int x1, y1, x2, y2;
int i, j;
unsigned char *pout = dst;
double f1, f2, f3, f4, f12, f34, val;
//输入图像的采样间隔
dx = (double) (width) / (double) (nw);
dy = (double) (height) / (double) (nh);
for (j=0; j<nh; ++j)
{
y = j * dy;
y1 = (int) y;
y2 = y1 + 1;
y2 = y2>height-1? height-1 : y2;
for (i=0; i<nw; ++i)
{
x = i * dx;
x1 = (int) x;
x2 = x1 + 1;
x2 = x2>width-1? width-1 : x2;
f1 = *(src + width * y1 + x1);
f3 = *(src + width * y1 + x2);
f2 = *(src + width * y2 + x1);
f4 = *(src + width * y2 + x2);
f12 = (f1 + (y-y1) * (f2 - f1));
f34 = (f3 + (y-y1) * (f4 - f3));
//+0.5是为了四舍五入，加0.00001是为了尽量避开取整时的大误差情况
val = f12 + (x - x1) * (f34 - f12) + 0.5;
if(val > 255)
*pout = 255;
else
*pout = (unsigned char) val;
++pout;
}
}
return 0;
}
int main( int argc, char** argv )
{
//0 read an image
char *imageName = "48220154_3.bmp";
Mat image;
image = imread( imageName, CV_LOAD_IMAGE_GRAYSCALE);
if( !image.data )
{
printf( " No image data \n " );
return -1;
}
//1 resize it using cv::imresize
cv::Mat mat;
cv::resize(image, mat, Size(12, 12), INTER_LINEAR);
printf("print output of cv::resize:\n");
std::cout << mat << std::endl;
// cv::cvtColor( image, gray_image, COLOR_RGB2GRAY );
// imwrite( "../../images/Gray_Image.jpg", gray_image );
//2 resize it using bilinear_image_resize
unsigned char *dst2 = (unsigned char*) malloc(12*12*sizeof(unsigned char));
if(!dst2){
printf("malloc failed\n");
return -1;
}
int wd = image.cols, ht =image.rows;
bilinear_image_resize(image.data, wd, ht, dst2, 12, 12);
//jin: this is a WRONG way to construct a Mat// OKay now, no need to set the 5th argument step
Mat mat2(12, 12, CV_8UC1, dst2);
//print dst2
printf("print output of bilinear_image_resize:\n");
std::cout << mat2 << std::endl;
return 0;
}