windows下的DPM经验

原文：http://blog.sciencenet.cn/blog-261330-663182.html

Discriminatively Trained Deformable Part Models的官网： http://www.cs.brown.edu/~pff/latent/

目前做目标检测最好的一个算法。

搞不懂为什么外国人老喜欢在linux下编代码，也许是因为版权的问题吧。

装了虚拟机在ubuntu下跑通了程序，但........你懂得（虚拟机能让你机子卡死）。

于是着手移植到windows下。

参考了pozen同学的博客：http://blog.csdn.net/pozen/article/details/7023742

启发很大，下面说说自己的调试过程：

1、把用到的文件dt.cc resize.cc fconv.cc features.cc的后缀都修改为cpp

2、dt.cpp中加：#define int32_t int

3、features.cpp、resize.cpp、fconv.cpp中加入

 #define bzero(a, b) memset(a, 0, b)
 int round(float a) { float tmp = a - (int)a; if( tmp >= 0.5 ) return (int)a + 1; else return (int)a; }

4、resize.cpp中的alphainfo ofs[len] 换成：alphainfo *ofs = new alphainfo[len] 当然要记得释放这个内存，但要注意放得位置。

之后就可以在matlab中运行compile进行编译了，这时会出现一些重定义的错误，应该是vc6.0对c++的一些不兼容，修改下就可以了。

5、输入demo()。查看结果。

调试过程中如何调试c程序参见前一篇文章。

说下自己的编译环境：vs2008&matlab2008b

贴出resize.cpp源代码（调试中因为内存错误折腾了很久）

 #include <math.h>
 #include <assert.h>
 #include <string.h>
 #include "mex.h"

 #define bzero(a, b) memset(a, 0, b)
 int round(float a) { float tmp = a - (int)a; if( tmp >= 0.5 ) return (int)a + 1; else return (int)a; }

 // struct used for caching interpolation values
 struct alphainfo {
   int si, di;
   double alpha;
 };

 // copy src into dst using interpolation values
 void alphacopy(double *src, double *dst, struct alphainfo *ofs, int n) {
   struct alphainfo *end = ofs + n;
   while (ofs != end) {
     dst[ofs->di] += ofs->alpha * src[ofs->si];
     ofs++;
   }
 }

 // resize along each column
 // result is transposed, so we can apply it twice for a complete resize
 void resize1dtran(double *src, int sheight, double *dst, int dheight,
           int width, int chan) {
   double scale = (double)dheight/(double)sheight;
   double invscale = (double)sheight/(double)dheight;

   // we cache the interpolation values since they can be
   // shared among different columns
   int len = (int)ceil(dheight*invscale) + 2*dheight;
   //alphainfo ofs[len];
   alphainfo *ofs = new alphainfo[len];
   int k = 0;
   for (int dy = 0; dy < dheight; dy++) {
     double fsy1 = dy * invscale;
     double fsy2 = fsy1 + invscale;
     int sy1 = (int)ceil(fsy1);
     int sy2 = (int)floor(fsy2);

     if (sy1 - fsy1 > 1e-3) {
       assert(k < len);
       assert(sy1-1 >= 0);
       ofs[k].di = dy*width;
       ofs[k].si = sy1-1;
       ofs[k++].alpha = (sy1 - fsy1) * scale;
     }

     for (int sy = sy1; sy < sy2; sy++) {
       assert(k < len);
       assert(sy < sheight);
       ofs[k].di = dy*width;
       ofs[k].si = sy;
       ofs[k++].alpha = scale;
     }

     if (fsy2 - sy2 > 1e-3) {
       assert(k < len);
       assert(sy2 < sheight);
       ofs[k].di = dy*width;
       ofs[k].si = sy2;
       ofs[k++].alpha = (fsy2 - sy2) * scale;
     }
   }

  // delete [] ofs;
   // resize each column of each color channel
   bzero(dst, chan*width*dheight*sizeof(double));
   for (int c = 0; c < chan; c++) {
     for (int x = 0; x < width; x++) {
       double *s = src + c*width*sheight + x*sheight;
       double *d = dst + c*width*dheight + x;
       alphacopy(s, d, ofs, k);
     }
   }
    delete [] ofs;
 }

 // main function
 // takes a double color image and a scaling factor
 // returns resized image
 mxArray *resize(const mxArray *mxsrc, const mxArray *mxscale) {
   double *src = (double *)mxGetPr(mxsrc);
   const int *sdims = (int*)mxGetDimensions(mxsrc);
   if (mxGetNumberOfDimensions(mxsrc) != 3 ||
       mxGetClassID(mxsrc) != mxDOUBLE_CLASS)
     mexErrMsgTxt("Invalid input");

   double scale = mxGetScalar(mxscale);
   if (scale > 1)
     mexErrMsgTxt("Invalid scaling factor");

   int ddims[3];
   ddims[0] = (int)round(sdims[0]*scale);
   ddims[1] = (int)round(sdims[1]*scale);
   ddims[2] = sdims[2];
   mxArray *mxdst = mxCreateNumericArray(3, (mwSize*)ddims, mxDOUBLE_CLASS, mxREAL);
   double *dst = (double *)mxGetPr(mxdst);

   double *tmp = (double *)mxCalloc(ddims[0]*sdims[1]*sdims[2], sizeof(double));
   resize1dtran(src, sdims[0], tmp, ddims[0], sdims[1], sdims[2]);
   resize1dtran(tmp, sdims[1], dst, ddims[1], ddims[0], sdims[2]);
   mxFree(tmp);

   return mxdst;
 }

 // matlab entry point
 // dst = resize(src, scale)
 // image should be color with double values
 void mexFunction(int nlhs, mxArray *plhs[], int nrhs, const mxArray *prhs[]) {
   if (nrhs != 2)
     mexErrMsgTxt("Wrong number of inputs");
   if (nlhs != 1)
     mexErrMsgTxt("Wrong number of outputs");
   plhs[0] = resize(prhs[0], prhs[1]);
 }