diff --git a/eco/feature_operator.cc b/eco/feature_operator.cc
index 8976082..ba9a024 100644
--- a/eco/feature_operator.cc
+++ b/eco/feature_operator.cc
@@ -78,7 +78,7 @@ vector<cv::Mat> init_projection_matrix(const ECO_FEATS &init_sample,
 			float mean = cv::mean(init_sample[i][j])[0]; // get the mean value of the mat;
 			for (size_t r = 0; r < (size_t)init_sample[i][j].rows; r++)
 				for (size_t c = 0; c < (size_t)init_sample[i][j].cols; c++)
-					feat_vec.at<float>(c * init_sample[i][j].rows + r, j) = init_sample[i][j].at<float>(r, c) - mean;
+					feat_vec.at<float>(r * init_sample[i][j].cols + c, j) = init_sample[i][j].at<float>(r, c) - mean;
 		}
 		result.push_back(feat_vec);
 	}
@@ -334,4 +334,4 @@ ECO_FEATS FeatureDotDivide(const ECO_FEATS &a, const ECO_FEATS &b)
 	}
 	return res;
 }
-} // namespace eco
\ No newline at end of file
+} // namespace eco