Add RGB <-> YCbCr conversion stuff to libaegisub

build/libaegisub/libaegisub.vcxproj

@@ -84,6 +84,7 @@
     <ClInclude Include="$(SrcDir)include\libaegisub\util.h" />
     <ClInclude Include="$(SrcDir)include\libaegisub\util_osx.h" />
     <ClInclude Include="$(SrcDir)include\libaegisub\vfr.h" />
+    <ClInclude Include="$(SrcDir)include\libaegisub\ycbcr_conv.h" />
     <ClInclude Include="$(SrcDir)lagi_pre.h" />
     <ClInclude Include="$(SrcDir)lua\modules\lpeg.h" />
   </ItemGroup>
@@ -120,6 +121,7 @@
     <ClCompile Include="$(SrcDir)common\thesaurus.cpp" />
     <ClCompile Include="$(SrcDir)common\util.cpp" />
     <ClCompile Include="$(SrcDir)common\vfr.cpp" />
+    <ClCompile Include="$(SrcDir)common\ycbcr_conv.cpp" />
     <ClCompile Include="$(SrcDir)lua\modules.cpp" />
     <ClCompile Include="$(SrcDir)lua\modules\lfs.cpp" />
     <ClCompile Include="$(SrcDir)lua\modules\lpeg.c">

build/libaegisub/libaegisub.vcxproj.filters

@@ -191,6 +191,9 @@
     <ClInclude Include="$(SrcDir)include\libaegisub\lua\modules.h">
       <Filter>Lua</Filter>
     </ClInclude>
+    <ClInclude Include="$(SrcDir)include\libaegisub\ycbcr_conv.h">
+      <Filter>Header Files</Filter>
+    </ClInclude>
   </ItemGroup>
   <ItemGroup>
     <ClCompile Include="$(SrcDir)windows\lagi_pre.cpp">
@@ -322,6 +325,9 @@
     <ClCompile Include="$(SrcDir)lua\modules\unicode.cpp">
       <Filter>Lua\Modules</Filter>
     </ClCompile>
+    <ClCompile Include="$(SrcDir)common\ycbcr_conv.cpp">
+      <Filter>Source Files\Common</Filter>
+    </ClCompile>
   </ItemGroup>
   <ItemGroup>
     <None Include="$(SrcDir)include\libaegisub\charsets.def">

libaegisub/Makefile

@@ -41,6 +41,7 @@ SRC += \
 	common/thesaurus.cpp \
 	common/util.cpp \
 	common/vfr.cpp \
+	common/ycbcr_conv.cpp \
 	lua/modules.cpp \
 	lua/modules/lfs.cpp \
 	lua/modules/lpeg.c \

libaegisub/common/ycbcr_conv.cpp

@@ -0,0 +1,98 @@
+// Copyright (c) 2014, Thomas Goyne <plorkyeran@aegisub.org>
+//
+// Permission to use, copy, modify, and distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice appear in all copies.
+//
+// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+// ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+// ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+// OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+//
+// Aegisub Project http://www.aegisub.org/
+
+#include "libaegisub/ycbcr_conv.h"
+
+namespace {
+double matrix_coefficients[][3] = {
+	{.299, .587, .114},    // BT.601
+	{.2126, .7152, .0722}, // BT.709
+	{.3, .59, .11},        // FCC
+	{.212, .701, .087},    // SMPTE 240M
+};
+
+void row_mult(std::array<double, 9>& arr, std::array<double, 3> values) {
+	size_t i = 0;
+	for (auto v : values) {
+		arr[i++] *= v;
+		arr[i++] *= v;
+		arr[i++] *= v;
+	}
+}
+
+void col_mult(std::array<double, 9>& m, std::array<double, 3> v) {
+	m = {{
+		m[0] * v[0], m[1] * v[1], m[2] * v[2],
+		m[3] * v[0], m[4] * v[1], m[5] * v[2],
+		m[6] * v[0], m[7] * v[1], m[8] * v[2],
+	}};
+}
+}
+
+namespace agi {
+void ycbcr_converter::init_src(ycbcr_matrix src_mat, ycbcr_range src_range) {
+	auto coeff = matrix_coefficients[(int)src_mat];
+	double Kr = coeff[0];
+	double Kg = coeff[1];
+	double Kb = coeff[2];
+	to_ycbcr = {{
+		Kr,         Kg,         Kb,
+		-Kr/(1-Kb), -Kg/(1-Kb), 1,
+		1,          -Kg/(1-Kr), -Kb/(1-Kr),
+	}};
+
+	if (src_range == ycbcr_range::pc) {
+		row_mult(to_ycbcr, {{1., .5, .5}});
+		shift_to = {{0, 128., 128.}};
+	}
+	else {
+		row_mult(to_ycbcr, {{219./255., 112./255., 112./255.}});
+		shift_to = {{16., 128., 128.}};
+	}
+}
+
+void ycbcr_converter::init_dst(ycbcr_matrix dst_mat, ycbcr_range dst_range) {
+	auto coeff = matrix_coefficients[(int)dst_mat];
+	double Kr = coeff[0];
+	double Kg = coeff[1];
+	double Kb = coeff[2];
+	from_ycbcr = {{
+		1,  0,             (1-Kr),
+		1, -(1-Kb)*Kb/Kg, -(1-Kr)*Kr/Kg,
+		1,  (1-Kb),        0,
+	}};
+
+	if (dst_range == ycbcr_range::pc) {
+		col_mult(from_ycbcr, {{1., 2., 2.}});
+		shift_from = {{0, -128., -128.}};
+	}
+	else {
+		col_mult(from_ycbcr, {{255./219., 255./112., 255./112.}});
+		shift_from = {{-16., -128., -128.}};
+	}
+}
+
+ycbcr_converter::ycbcr_converter(ycbcr_matrix mat, ycbcr_range range) {
+	init_src(mat, range);
+	init_dst(mat, range);
+}
+
+ycbcr_converter::ycbcr_converter(ycbcr_matrix src_mat, ycbcr_range src_range, ycbcr_matrix dst_mat, ycbcr_range dst_range) {
+	init_src(src_mat, src_range);
+	init_dst(dst_mat, dst_range);
+}
+}
+

libaegisub/include/libaegisub/ycbcr_conv.h

@@ -0,0 +1,89 @@
+// Copyright (c) 2014, Thomas Goyne <plorkyeran@aegisub.org>
+//
+// Permission to use, copy, modify, and distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice appear in all copies.
+//
+// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+// ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+// ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+// OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+//
+// Aegisub Project http://www.aegisub.org/
+
+#include <array>
+#include <cstdint>
+
+namespace agi {
+enum class ycbcr_matrix {
+	bt601,
+	bt709,
+	fcc,
+	smpte_240m
+};
+
+enum class ycbcr_range {
+	tv,
+	pc
+};
+
+/// A converter between YCbCr colorspaces and RGB
+class ycbcr_converter {
+	std::array<double, 9> from_ycbcr;
+	std::array<double, 9> to_ycbcr;
+
+	std::array<double, 3> shift_from;
+	std::array<double, 3> shift_to;
+
+	void init_dst(ycbcr_matrix dst_mat, ycbcr_range dst_range);
+	void init_src(ycbcr_matrix src_mat, ycbcr_range src_range);
+
+	template<typename T>
+	static std::array<double, 3> prod(std::array<double, 9> m, std::array<T, 3> v) {
+		return {{
+			m[0] * v[0] + m[1] * v[1] + m[2] * v[2],
+			m[3] * v[0] + m[4] * v[1] + m[5] * v[2],
+			m[6] * v[0] + m[7] * v[1] + m[8] * v[2],
+		}};
+	}
+
+	template<typename T, typename U>
+	static std::array<double, 3> add(std::array<T, 3> left, std::array<U, 3> right) {
+		return {{left[0] + right[0], left[1] + right[1], left[2] + right[2]}};
+	}
+
+	static uint8_t clamp(double v) {
+		auto i = static_cast<int>(v);
+		i = i > 255 ? 255 : i;
+		return i < 0 ? 0 : i;
+	}
+
+	static std::array<uint8_t, 3> to_uint8_t(std::array<double, 3> val) {
+		return {{clamp(val[0] + .5), clamp(val[1] + .5), clamp(val[2] + .5)}};
+	}
+
+public:
+	ycbcr_converter(ycbcr_matrix mat, ycbcr_range range);
+	ycbcr_converter(ycbcr_matrix src_mat, ycbcr_range src_range, ycbcr_matrix dst_mat, ycbcr_range dst_range);
+
+	/// Convert from rgb to dst_mat/dst_range
+	std::array<uint8_t, 3> rgb_to_ycbcr(std::array<uint8_t, 3> input) const {
+		return to_uint8_t(add(prod(to_ycbcr, input), shift_to));
+	}
+
+	/// Convert from src_mat/src_range to rgb
+	std::array<uint8_t, 3> ycbcr_to_rgb(std::array<uint8_t, 3> input) const {
+		return to_uint8_t(prod(from_ycbcr, add(input, shift_from)));
+	}
+
+	/// Convert rgb to ycbcr using src_mat and then back using dst_mat
+	std::array<uint8_t, 3> rgb_to_rgb(std::array<uint8_t, 3> input) const {
+		return to_uint8_t(prod(from_ycbcr,
+			add(add(prod(to_ycbcr, input), shift_to), shift_from)));
+	}
+};
+}
+