69 lines
2.3 KiB
C++
69 lines
2.3 KiB
C++
//
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// Copyright 2005-2007 Adobe Systems Incorporated
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//
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// Distributed under the Boost Software License, Version 1.0
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// See accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt
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//
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#include <boost/gil/extension/io/jpeg.hpp>
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// Demonstrates how to compute gradients along the x-axis
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// This example converts the input image to a greyscale view via color_converted_view,
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// and then relies on the function static_transform to apply the operation halfdiff_cast_channels.
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// The result is captured in a view, initially blacked out via a call to fill_pixels (defined in
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// include/boost/gil/algorithm.hpp)
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// static_transform is defined in include/boost/gil/color_based_algorithm.hpp and applies an operation
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// to either a single source or two sources and a destination (as is the case here).
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// In this example, the gradient is calculated as half the difference between the two pixels surrounding x
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// in the loop in x_gradient.
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using namespace boost::gil;
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template <typename Out>
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struct halfdiff_cast_channels {
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template <typename T> Out operator()(const T& in1, const T& in2) const {
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return Out((in2-in1)/2);
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}
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};
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template <typename SrcView, typename DstView>
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void x_gradient(SrcView const& src, DstView const& dst)
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{
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using dst_channel_t = typename channel_type<DstView>::type;
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for (int y = 0; y < src.height(); ++y)
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{
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typename SrcView::x_iterator src_it = src.row_begin(y);
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typename DstView::x_iterator dst_it = dst.row_begin(y);
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for (int x = 1; x < src.width() - 1; ++x)
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{
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static_transform(src_it[x - 1], src_it[x + 1], dst_it[x],
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halfdiff_cast_channels<dst_channel_t>());
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}
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}
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}
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template <typename SrcView, typename DstView>
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void x_luminosity_gradient(SrcView const& src, DstView const& dst)
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{
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using gray_pixel_t = pixel<typename channel_type<SrcView>::type, gray_layout_t>;
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x_gradient(color_converted_view<gray_pixel_t>(src), dst);
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}
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int main()
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{
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rgb8_image_t img;
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read_image("test.jpg",img, jpeg_tag{});
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gray8s_image_t img_out(img.dimensions());
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fill_pixels(view(img_out),int8_t(0));
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x_luminosity_gradient(const_view(img), view(img_out));
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write_view("out-x_gradient.jpg",color_converted_view<gray8_pixel_t>(const_view(img_out)), jpeg_tag{});
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return 0;
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}
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