LLC(Locality-constrained Linear Coding)基于OpenCV的C++源码实现

《Locality-constrained Linear Coding for Image Classification》的作者提供Matlab的代码实现，见http://www.ifp.illinois.edu/~jyang29/LLC.htm。

下面是根据作者的代码，基于OpenCV，实现的C++版的LLC：

cv::Mat BowModel::findKNN(cv::Mat &codebook, cv::Mat &input, int k) {
  int nbase = codebook.rows;
  int nquery = input.rows;
  Mat ii = input.mul(input);
  Mat cc = codebook.mul(codebook);
  
  Mat sii(nquery,1,CV_32FC1);
  sii.setTo(0);
  Mat scc(nbase,1,CV_32FC1);
  scc.setTo(0);
  for (int i = 0; i(i,0) += ii.at(i,j);
  	}
  }
  for (int i = 0; i(i,0) += cc.at(i,j);
  	}
  }
  
  Mat D(nquery,nbase,CV_32FC1);
  for (int i = 0; i(i,j) = sii.at(i,0);
  	}
  }
  
  Mat ct;
  transpose(codebook, ct);
  Mat D1 = 2*input*ct;
  
  Mat scct;
  transpose(scc, scct);
  Mat D2(nquery, nbase, CV_32FC1);
  for (int i = 0; i(i,j) = scct.at(0,j);
  	}
  }
  
  D = D - D1 + D2;
  Mat SD;
  sortIdx(D, SD, CV_SORT_EVERY_ROW+CV_SORT_ASCENDING);
  Mat IDX(nquery,k,CV_8UC1);
  for (int i = 0; i(i,j) = SD.row(i).col(j).at(0,0);
  	}
  }
  
  ii.release();
  cc.release();
  sii.release();
  scc.release();
  D.release();
  ct.release();
  D1.release();
  scct.release();
  D2.release();
  SD.release();
  return IDX;
}

cv::Mat BowModel::llccode(cv::Mat &codebook, cv::Mat &input, cv::Mat IDX, int k)
{
	int nquery = input.rows;
	int nbase = codebook.rows;
	int dim = codebook.cols;

	Mat II = Mat::eye(k, k, CV_32FC1);
	Mat Coeff(nquery,nbase,CV_32FC1);
	Coeff.setTo(0);
	Mat z;
	Mat z1(k,dim,CV_32FC1);
	Mat z2(k,dim,CV_32FC1);
	Mat C;
	Mat un(k,1,CV_32FC1);
	un.setTo(1);
	Mat temp;
	Mat temp2;
	Mat w;
	Mat wt;

	for (int n = 0; n(i,j) = codebook.at(IDX.at(n,i),j);
				z2.at(i,j) = input.at(n,j);
			}
		}
		z = z1 - z2;
		transpose(z, temp);
		C = z*temp;
		C = C + II*(1e-4)*trace(C)[0];
		invert(C,temp2);
		w = temp2*un;
		float sum_w=0;
		for (int i = 0; i(i,0);
		}
		w = w/sum_w;
		transpose(w, wt);
		for (int i = 0; i(n,IDX.at(n,i)) = wt.at(0,i);
		}
	}

	II.release();
	z.release();
	z1.release();
	z2.release();
	C.release();
	un.release();
	temp.release();
	temp2.release();
	w.release();
	wt.release();

	return Coeff;
}