Added the scan_image() routine. It is a tool for sliding a set of rectangles

over an image space and finding the locations where the sum of pixels in
the rectangles exceeds a threshold.

dlib/image_processing.h

+// Copyright (C) 2011  Davis E. King (davis@dlib.net)
+// License: Boost Software License   See LICENSE.txt for the full license.
+#ifndef DLIB_IMAGE_PROCESSInG_H___
+#define DLIB_IMAGE_PROCESSInG_H___ 
+
+#include "image_processing/scan_image.h"
+
+#endif // DLIB_IMAGE_PROCESSInG_H___
+
+

dlib/image_processing/scan_image_abstract.h

+// Copyright (C) 2011  Davis E. King (davis@dlib.net)
+// License: Boost Software License   See LICENSE.txt for the full license.
+#undef DLIB_SCAN_iMAGE_ABSTRACT_H__
+#ifdef DLIB_SCAN_iMAGE_ABSTRACT_H__
+
+#include <vector>
+#include <utility>
+#include "../algs.h"
+
+namespace dlib
+{
+
+// ----------------------------------------------------------------------------------------
+
+    template <
+        typename image_array_type
+        >
+    bool all_images_same_size (
+        const image_array_type& images
+    );
+    /*!
+        requires
+            - image_array_type       == an implementation of array/array_kernel_abstract.h
+            - image_array_type::type == an implementation of array2d/array2d_kernel_abstract.h
+        ensures
+            - if (all elements of images have the same dimensions (i.e. 
+              for all i and j: get_rect(images[i]) == get_rect(images[j]))) then
+                - returns true
+            - else
+                - returns false
+    !*/
+
+// ----------------------------------------------------------------------------------------
+
+    template <
+        typename image_array_type
+        >
+    double sum_of_rects_in_images (
+        const image_array_type& images,
+        const std::vector<std::pair<unsigned int, rectangle> >& rects,
+        const point& origin
+    );
+    /*!
+        requires
+            - image_array_type             == an implementation of array/array_kernel_abstract.h
+            - image_array_type::type       == an implementation of array2d/array2d_kernel_abstract.h
+            - image_array_type::type::type == a scalar pixel type (e.g. int rather than rgb_pixel)
+            - all_images_same_size(images) == true
+            - for all valid i: rects[i].first < images.size()
+              (i.e. all the rectangles must reference valid elements of images)
+        ensures
+            - returns the sum of the pixels inside the given rectangles.  To be precise, 
+              let RECT_SUM[i] = sum of pixels inside the rectangle translate_rect(rects[i].second, origin) 
+              from the image images[rects[i].first].  Then this function returns the 
+              sum of RECT_SUM[i] for all the valid values of i.
+    !*/
+
+// ----------------------------------------------------------------------------------------
+
+    template <
+        typename image_array_type
+        >
+    void scan_image (
+        std::vector<std::pair<double, point> >& dets,
+        const image_array_type& images,
+        const std::vector<std::pair<unsigned int, rectangle> >& rects,
+        const double thresh,
+        const unsigned long max_dets
+    );
+    /*!
+        requires
+            - image_array_type             == an implementation of array/array_kernel_abstract.h
+            - image_array_type::type       == an implementation of array2d/array2d_kernel_abstract.h
+            - image_array_type::type::type == a scalar pixel type (e.g. int rather than rgb_pixel)
+            - images.size() > 0
+            - rects.size() > 0 
+            - all_images_same_size(images) == true
+            - for all valid i: rects[i].first < images.size()
+              (i.e. all the rectangles must reference valid elements of images)
+        ensures
+            - slides the set of rectangles over the image space and reports the locations
+              which give a sum bigger than thresh. 
+            - Specifically, we have:
+                - #dets.size() <= max_dets
+                  (note that dets is cleared before new detections are added by scan_image())
+                - for all valid i:
+                    - #dets[i].first == sum_of_rects_in_images(images,rects,#dets[i].second) >= thresh
+    !*/
+
+// ----------------------------------------------------------------------------------------
+
+}
+
+#endif // DLIB_SCAN_iMAGE_ABSTRACT_H__
+
+
+

dlib/test/CMakeLists.txt

@@ -82,6 +82,7 @@ set (tests
    rand.cpp
    read_write_mutex.cpp
    reference_counter.cpp
+   scan_image.cpp
    sequence.cpp
    serialize.cpp
    set.cpp

dlib/test/makefile

@@ -97,6 +97,7 @@ SRC += queue.cpp
 SRC += rand.cpp
 SRC += read_write_mutex.cpp
 SRC += reference_counter.cpp
+SRC += scan_image.cpp
 SRC += sequence.cpp
 SRC += serialize.cpp
 SRC += set.cpp