Added the randomly_sample_image_features() routine.

dlib/statistics.h

@@ -6,6 +6,7 @@
 #include "statistics/statistics.h"
 #include "statistics/dpca.h"
 #include "statistics/random_subset_selector.h"
+#include "statistics/image_feature_sampling.h"
 
 #endif // DLIB_STATISTICs_H_ 
 

dlib/statistics/image_feature_sampling.h

@@ -0,0 +1,69 @@
+// Copyright (C) 2011  Davis E. King (davis@dlib.net)
+// License: Boost Software License   See LICENSE.txt for the full license.
+#ifndef DLIB_IMAGE_FEATURE_SaMPLING_H__
+#define DLIB_IMAGE_FEATURE_SaMPLING_H__
+
+#include "image_feature_sampling_abstract.h"
+#include "../statistics.h"
+#include "../image_transforms.h"
+
+namespace dlib
+{
+
+// ----------------------------------------------------------------------------------------
+
+    template <
+        typename image_array_type,
+        typename feature_extractor_type,
+        typename pyramid_type
+        >
+    random_subset_selector<typename feature_extractor_type::descriptor_type> randomly_sample_image_features (
+        const image_array_type& images,
+        const pyramid_type& pyr,
+        const feature_extractor_type& fe_,
+        unsigned long num
+    )
+    {
+        feature_extractor_type fe;
+        fe.copy_configuration(fe_);
+        random_subset_selector<typename feature_extractor_type::descriptor_type> basis;
+        basis.set_max_size(num);
+
+        typedef typename image_array_type::type image_type;
+        image_type temp_img, temp_img2;
+
+        for (unsigned long i = 0; i < images.size(); ++i)
+        {
+            assign_image(temp_img, images[i]);
+
+            while (temp_img.nr() > 10 && temp_img.nc() > 10)
+            {
+                fe.load(temp_img);
+                for (long r = 0; r < fe.nr(); ++r)
+                {
+                    for (long c = 0; c < fe.nc(); ++c)
+                    {
+                        if (basis.next_add_accepts())
+                        {
+                            basis.add(fe(r,c));
+                        }
+                        else
+                        {
+                            basis.add();
+                        }
+                    }
+                }
+
+                pyr(temp_img, temp_img2);
+                temp_img2.swap(temp_img);
+            }
+        }
+        return basis;
+    }
+
+// ----------------------------------------------------------------------------------------
+
+}
+
+#endif // DLIB_IMAGE_FEATURE_SaMPLING_H__
+

dlib/statistics/image_feature_sampling_abstract.h

@@ -0,0 +1,44 @@
+// Copyright (C) 2011  Davis E. King (davis@dlib.net)
+// License: Boost Software License   See LICENSE.txt for the full license.
+#undef DLIB_IMAGE_FEATURE_SaMPLING_ABSTRACT_H__
+#ifdef DLIB_IMAGE_FEATURE_SaMPLING_ABSTRACT_H__
+
+#include "random_subset_selector_abstract.h"
+
+namespace dlib
+{
+
+// ----------------------------------------------------------------------------------------
+
+    template <
+        typename image_array_type,
+        typename feature_extractor_type,
+        typename pyramid_type
+        >
+    random_subset_selector<typename feature_extractor_type::descriptor_type> randomly_sample_image_features (
+        const image_array_type& images,
+        const pyramid_type& pyr,
+        const feature_extractor_type& fe,
+        unsigned long num
+    );
+    /*!
+        requires
+            - pyramid_type == a type compatible with the image pyramid objects defined 
+              in dlib/image_transforms/image_pyramid_abstract.h
+            - feature_extractor_type == a local image feature extractor type such as the
+              dlib::hog_image
+            - image_array_type == an implementation of dlib/array/array_kernel_abstract.h
+              and it must contain image objects which can be passed to pyr() and fe.load()
+        ensures
+            - creates an image pyramid for each image in images and performs feature
+              extraction on each pyramid level.  Then selects a random subsample of at 
+              most num local feature vectors and returns it.
+    !*/
+
+// ----------------------------------------------------------------------------------------
+
+}
+
+#endif // DLIB_IMAGE_FEATURE_SaMPLING_ABSTRACT_H__
+
+