implemented box_filter

implemented `blur` function

tests added for `box_filter`

closes #382

include/boost/gil/image_processing/filter.hpp

@@ -0,0 +1,64 @@
+//
+// Copyright 2019 Miral Shah <miralshah2211@gmail.com>
+//
+// Use, modification and distribution are subject to the Boost Software License,
+// Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_GIL_IMAGE_PROCESSING_FILTER_HPP
+#define BOOST_GIL_IMAGE_PROCESSING_FILTER_HPP
+
+#include <cstddef>
+#include <vector>
+
+#include <boost/gil/image.hpp>
+#include <boost/gil/image_view.hpp>
+#include <boost/gil/extension/numeric/kernel.hpp>
+#include <boost/gil/extension/numeric/convolve.hpp>
+
+namespace boost { namespace gil {
+
+template <typename SrcView, typename DstView>
+void box_filter(
+    SrcView const& src_view,
+    DstView const& dst_view,
+    std::size_t kernel_size,
+    long int anchor = -1,
+    bool normalize=true,
+    convolve_boundary_option option = convolve_option_extend_zero
+)
+{
+    gil_function_requires<ImageViewConcept<SrcView>>();
+    gil_function_requires<MutableImageViewConcept<DstView>>();
+    static_assert(color_spaces_are_compatible
+    <
+        typename color_space_type<SrcView>::type,
+        typename color_space_type<DstView>::type
+    >::value, "Source and destination views must have pixels with the same color space");
+
+    std::vector<float> kernel_values;
+    if (normalize) { kernel_values.resize(kernel_size, 1.0f / float(kernel_size)); }
+    else { kernel_values.resize(kernel_size, 1.0f); }
+
+    if (anchor == -1) anchor = kernel_size / 2;
+    kernel_1d<float> kernel(kernel_values.begin(), kernel_size, anchor);
+
+    convolve_1d<pixel<float, typename SrcView::value_type::layout_t>>(src_view, kernel, dst_view);
+}
+
+template <typename SrcView, typename DstView>
+void blur(
+    SrcView const& src_view,
+    DstView const& dst_view,
+    std::size_t kernel_size,
+    std::size_t anchor = kernel_size / 2,
+    convolve_boundary_option option = convolve_option_extend_zero
+)
+{
+    box_filter(src_view, dst_view, kernel_size, anchor, true, option);
+}
+
+}} //namespace boost::gil
+
+#endif // !BOOST_GIL_IMAGE_PROCESSING_FILTER_HPP

test/core/image_processing/CMakeLists.txt

@@ -29,7 +29,8 @@ endforeach()
 
 foreach(_name
   lanczos_scaling
-  simple_kernels)
+  simple_kernels
+  box_filter)
   set(_test t_core_image_processing_${_name})
   set(_target test_core_image_processing_${_name})
 

test/core/image_processing/box_filter.cpp

@@ -0,0 +1,67 @@
+//
+// Copyright 2019 Miral Shah <miralshah2211@gmail.com>
+//
+// Use, modification and distribution are subject to the Boost Software License,
+// Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#define BOOST_TEST_MODULE test_image_processing_box_filter
+#include "unit_test.hpp"
+
+#include <boost/gil/image_view.hpp>
+#include <boost/gil/algorithm.hpp>
+#include <boost/gil/gray.hpp>
+#include <boost/core/lightweight_test.hpp>
+#include <boost/gil/image_processing/filter.hpp>
+
+
+namespace gil = boost::gil;
+
+std::uint8_t img[] =
+{
+    0, 0, 0, 0, 0, 0, 0, 0, 0,
+    0, 0, 0, 0, 0, 0, 0, 0, 0,
+    0, 0, 255, 0, 0, 0, 255, 0, 0,
+    0, 0, 0, 255, 0, 255, 0, 0, 0,
+    0, 0, 0, 0, 255, 0, 0, 0, 0,
+    0, 0, 0, 255, 0, 255, 0, 0, 0,
+    0, 0, 255, 0, 0, 0, 255, 0, 0,
+    0, 0, 0, 0, 0, 0, 0, 0, 0,
+    0, 0, 0, 0, 0, 0, 0, 0, 0
+};
+
+std::uint8_t output[] =
+{
+    0, 0, 0, 0, 0, 0, 0, 0, 0,
+    0, 28, 28, 28, 0, 28, 28, 28, 0,
+    0, 28, 56, 56, 56, 56, 56, 28, 0,
+    0, 28, 56, 85, 85, 85, 56, 28, 0,
+    0, 0, 56, 85, 141, 85, 56, 0, 0,
+    0, 28, 56, 85, 85, 85, 56, 28, 0,
+    0, 28, 56, 56, 56, 56, 56, 28, 0,
+    0, 28, 28, 28, 0, 28, 28, 28, 0,
+    0, 0, 0, 0, 0, 0, 0, 0, 0
+};
+
+BOOST_AUTO_TEST_SUITE(filter)
+
+BOOST_AUTO_TEST_CASE(box_filter_with_default_parameters)
+{
+    gil::gray8c_view_t src_view =
+        gil::interleaved_view(9, 9, reinterpret_cast<const gil::gray8_pixel_t*>(img), 9);
+
+    gil::image<gil::gray8_pixel_t> temp_img(src_view.width(), src_view.height());
+    typename gil::image<gil::gray8_pixel_t>::view_t temp_view = view(temp_img);
+    gil::gray8_view_t dst_view(temp_view);
+
+    gil::box_filter(src_view, dst_view, 3);
+
+    gil::gray8c_view_t out_view =
+        gil::interleaved_view(9, 9, reinterpret_cast<const gil::gray8_pixel_t*>(output), 9);
+
+
+    BOOST_TEST(gil::equal_pixels(out_view, dst_view));
+}
+
+BOOST_AUTO_TEST_SUITE_END()