Merge pull request #231 from GilLevi/AddingLATCH

Adding the LATCH descriptor

Author: vpisarev

modules/xfeatures2d/include/opencv2/xfeatures2d.hpp

@@ -145,6 +145,34 @@ class CV_EXPORTS_W LUCID : public Feature2D
 };
 
 
+/*
+* LATCH Descriptor
+*/
+
+/** latch Class for computing the LATCH descriptor.
+If you find this code useful, please add a reference to the following paper in your work:
+Gil Levi and Tal Hassner, "LATCH: Learned Arrangements of Three Patch Codes", arXiv preprint arXiv:1501.03719, 15 Jan. 2015
+
+LATCH is a binary descriptor based on learned comparisons of triplets of image patches.
+
+* bytes is the size of the descriptor - can be 64, 32, 16, 8, 4, 2 or 1
+* rotationInvariance - whether or not the descriptor should compansate for orientation changes.
+* half_ssd_size - the size of half of the mini-patches size. For example, if we would like to compare triplets of patches of size 7x7x
+    then the half_ssd_size should be (7-1)/2 = 3.
+
+Note: the descriptor can be coupled with any keypoint extractor. The only demand is that if you use set rotationInvariance = True then 
+    you will have to use an extractor which estimates the patch orientation (in degrees). Examples for such extractors are ORB and SIFT.
+
+Note: a complete example can be found under /samples/cpp/tutorial_code/xfeatures2D/latch_match.cpp
+
+*/
+class CV_EXPORTS LATCH : public DescriptorExtractor
+{
+public:
+	static Ptr<LATCH> create(int bytes = 32, bool rotationInvariance = true, int half_ssd_size=3);
+};
+
+
 
 //! @}
 

modules/xfeatures2d/perf/perf_latch.cpp

@@ -0,0 +1,34 @@
+#include "perf_precomp.hpp"
+
+using namespace std;
+using namespace cv;
+using namespace cv::xfeatures2d;
+using namespace perf;
+using std::tr1::make_tuple;
+using std::tr1::get;
+
+typedef perf::TestBaseWithParam<std::string> latch;
+
+#define LATCH_IMAGES \
+    "cv/detectors_descriptors_evaluation/images_datasets/leuven/img1.png",\
+    "stitching/a3.png"
+
+PERF_TEST_P(latch, extract, testing::Values(LATCH_IMAGES))
+{
+    string filename = getDataPath(GetParam());
+    Mat frame = imread(filename, IMREAD_GRAYSCALE);
+    ASSERT_FALSE(frame.empty()) << "Unable to load source image " << filename;
+
+    Mat mask;
+    declare.in(frame).time(90);
+
+    Ptr<SURF> detector = SURF::create();
+    vector<KeyPoint> points;
+    detector->detect(frame, points, mask);
+
+    Ptr<LATCH> descriptor = LATCH::create();
+    vector<uchar> descriptors;
+    TEST_CYCLE() descriptor->compute(frame, points, descriptors);
+
+    SANITY_CHECK(descriptors, 1e-4);
+}