Initial commit.

.gitignore

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+*.dll
+*.so
+*.dylib
+*.o
+*.dSYM
+testCIEDE2000
+

CIEDE2000.cpp

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+/*
+ * CIEDE2000.cpp
+ * Part of http://github.com/gfiumara/CIEDE2000 by Gregory Fiumara.
+ * See LICENSE for details.
+ */
+
+#include <cmath>
+
+#include <CIEDE2000.h>
+
+/*******************************************************************************
+ * Conversions.
+ ******************************************************************************/
+
+constexpr double
+CIEDE2000::deg2Rad(
+    const double deg)
+{
+	return (deg * (M_PI / 180.0));
+}
+
+constexpr double
+CIEDE2000::rad2Deg(
+    const double rad)
+{
+	return ((180.0 / M_PI) * rad);
+}
+
+double
+CIEDE2000::CIEDE2000(
+    const LAB &lab1,
+    const LAB &lab2)
+{
+	/* 
+	 * "For these and all other numerical/graphical 􏰀delta E00 values
+	 * reported in this article, we set the parametric weighting factors
+	 * to unity(i.e., k_L = k_C = k_H = 1.0)." (Page 27).
+	 */
+	const double k_L = 1.0, k_C = 1.0, k_H = 1.0;
+	const double deg360InRad = CIEDE2000::deg2Rad(360.0);
+	const double deg180InRad = CIEDE2000::deg2Rad(180.0);
+	const double pow25To7 = 6103515625.0; /* pow(25, 7) */
+
+	/*
+	 * Step 1 
+	 */
+	/* Equation 2 */
+	double C1 = sqrt((lab1.a * lab1.a) + (lab1.b * lab1.b));
+	double C2 = sqrt((lab2.a * lab2.a) + (lab2.b * lab2.b));
+	/* Equation 3 */
+	double barC = (C1 + C2) / 2.0;
+	/* Equation 4 */
+	double G = 0.5 * (1 - sqrt(pow(barC, 7) / (pow(barC, 7) + pow25To7)));
+	/* Equation 5 */
+	double a1Prime = (1.0 + G) * lab1.a;
+	double a2Prime = (1.0 + G) * lab2.a;
+	/* Equation 6 */
+	double CPrime1 = sqrt((a1Prime * a1Prime) + (lab1.b * lab1.b));
+	double CPrime2 = sqrt((a2Prime * a2Prime) + (lab2.b * lab2.b));
+	/* Equation 7 */
+	double hPrime1;
+	if (lab1.b == 0 && a1Prime == 0)
+		hPrime1 = 0.0;
+	else
+		hPrime1 = atan2(lab1.b, a1Prime);
+		/* 
+		 * This must be converted to a hue angle in degrees between 0 
+		 * and 360 by addition of 2􏰏 to negative hue angles.
+		 */
+		if (hPrime1 < 0)
+			hPrime1 += deg360InRad;
+	double hPrime2;
+	if (lab2.b == 0 && a2Prime == 0)
+		hPrime2 = 0.0;
+	else
+		hPrime2 = atan2(lab2.b, a2Prime);
+		/* 
+		 * This must be converted to a hue angle in degrees between 0 
+		 * and 360 by addition of 2􏰏 to negative hue angles.
+		 */
+		if (hPrime2 < 0)
+			hPrime2 += deg360InRad;
+
+	/*
+	 * Step 2
+	 */
+	/* Equation 8 */
+	double deltaLPrime = lab2.l - lab1.l;
+	/* Equation 9 */
+	double deltaCPrime = CPrime2 - CPrime1;
+	/* Equation 10 */
+	double deltahPrime;
+	double CPrimeProduct = CPrime1 * CPrime2;
+	if (CPrimeProduct == 0)
+		deltahPrime = 0;
+	else {
+		/* Avoid the fabs() call */
+		deltahPrime = hPrime2 - hPrime1;
+		if (deltahPrime < -deg180InRad)
+			deltahPrime += deg360InRad;
+		else if (deltahPrime > deg180InRad)
+			deltahPrime -= deg360InRad;
+	}
+	/* Equation 11 */
+	double deltaHPrime = 2.0 * sqrt(CPrimeProduct) *
+	    sin(deltahPrime / 2.0);
+
+	/*
+	 * Step 3
+	 */
+	/* Equation 12 */
+	double barLPrime = (lab1.l + lab2.l) / 2.0;
+	/* Equation 13 */
+	double barCPrime = (CPrime1 + CPrime2) / 2.0;
+	/* Equation 14 */
+	double barhPrime, hPrimeSum = hPrime1 + hPrime2;
+	if (CPrime1 * CPrime2 == 0) {
+		barhPrime = hPrimeSum;
+	} else {
+		if (fabs(hPrime1 - hPrime2) <= deg180InRad)
+			barhPrime = hPrimeSum / 2.0;
+		else {
+			if (hPrimeSum < deg360InRad)
+				barhPrime = (hPrimeSum + deg360InRad) / 2.0;
+			else
+				barhPrime = (hPrimeSum - deg360InRad) / 2.0;
+		}
+	}
+	/* Equation 15 */
+	double T = 1.0 - (0.17 * cos(barhPrime - CIEDE2000::deg2Rad(30.0))) +
+	    (0.24 * cos(2.0 * barhPrime)) +
+	    (0.32 * cos((3.0 * barhPrime) + CIEDE2000::deg2Rad(6.0))) - 
+	    (0.20 * cos((4.0 * barhPrime) - CIEDE2000::deg2Rad(63.0)));
+	/* Equation 16 */
+	double deltaTheta = CIEDE2000::deg2Rad(30.0) *
+	    exp(-pow((barhPrime - deg2Rad(275.0)) / deg2Rad(25.0), 2.0));
+	/* Equation 17 */
+	double R_C = 2.0 * sqrt(pow(barCPrime, 7.0) /
+	    (pow(barCPrime, 7.0) + pow25To7));
+	/* Equation 18 */
+	double S_L = 1 + ((0.015 * pow(barLPrime - 50.0, 2.0)) /
+	    sqrt(20 + pow(barLPrime - 50.0, 2.0)));
+	/* Equation 19 */
+	double S_C = 1 + (0.045 * barCPrime);
+	/* Equation 20 */
+	double S_H = 1 + (0.015 * barCPrime * T);
+	/* Equation 21 */
+	double R_T = (-sin(2.0 * deltaTheta)) * R_C;
+
+	/* Equation 22 */
+	double deltaE = sqrt(
+	    pow(deltaLPrime / (k_L * S_L), 2.0) +
+	    pow(deltaCPrime / (k_C * S_C), 2.0) +
+	    pow(deltaHPrime / (k_H * S_H), 2.0) + 
+	    (R_T * (deltaCPrime / (k_C * S_C)) * (deltaHPrime / (k_H * S_H))));
+
+	return (deltaE);
+}
+
+/*******************************************************************************
+ * Operators.
+ ******************************************************************************/
+
+std::ostream&
+operator<<(
+    std::ostream &s,
+    const CIEDE2000::LAB &labColor)
+{
+	return (s << "CIELAB(" << labColor.l << "," << labColor.a << "," <<
+	    labColor.b << ")");
+}
+

CIEDE2000.h

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+/*
+ * CIEDE2000.h
+ * Part of http://github.com/gfiumara/CIEDE2000 by Gregory Fiumara.
+ * See LICENSE for details.
+ */
+
+#ifndef GPF_CIEDE2000_H_
+#define GPF_CIEDE2000_H_
+
+#include <ostream>
+
+#ifndef M_PI
+#define M_PI        3.14159265358979323846264338327950288   /* pi */
+#endif
+
+/** Namespace containing all necessary objects and methods for CIEDE2000 */
+namespace CIEDE2000
+{
+	/***********************************************************************
+	 * Types.
+	 **********************************************************************/
+
+	/** A color in CIELAB colorspace */
+	struct LAB
+	{
+		/** Lightness */
+		double l;
+		/** Color-opponent a dimension */
+		double a;
+		/** Color-opponent b dimension */
+		double b;
+	};
+	/** Convenience definition for struct LAB */
+	using LAB = struct LAB;
+
+	/***********************************************************************
+	 * Operations.
+	 **********************************************************************/
+
+	/**
+	 * @brief
+	 * Obtain Delta-E 2000 value.
+	 * @details
+	 * Based on the paper "The CIEDE2000 Color-Difference Formula: 
+	 * Implementation Notes, Supplementary Test Data, and Mathematical 
+	 * Observations" by Gaurav Sharma, Wencheng Wu, and Edul N. Dalal,
+	 * from http://www.ece.rochester.edu/~gsharma/ciede2000/.
+	 *
+	 * @param lab1
+	 * First color in LAB colorspace.
+	 * @param lab2
+	 * Second color in LAB colorspace.
+	 *
+	 * @return
+	 * Delta-E difference between lab1 and lab2.
+	 */
+	double
+	CIEDE2000(
+	    const LAB &lab1,
+	    const LAB &lab2);
+
+	/***********************************************************************
+	 * Conversions.
+	 **********************************************************************/
+
+    	/**
+    	 * @brief
+    	 * Convert degrees to radians.
+    	 *
+    	 * @param deg
+    	 * Angle in degrees.
+    	 *
+    	 * @return
+    	 * deg in radians.
+    	 */
+	constexpr double
+	deg2Rad(
+	    const double deg);
+
+	/**
+    	 * @brief
+    	 * Convert radians to degrees.
+    	 *
+    	 * @param rad
+    	 * Angle in radians.
+    	 *
+    	 * @return
+    	 * rad in degrees.
+    	 */
+        constexpr double
+	rad2Deg(
+	    const double rad);
+}
+
+/*******************************************************************************
+ * Conversions.
+ ******************************************************************************/
+
+/**
+ * @brief
+ * LAB output stream operator.
+ *
+ * @param s
+ * Output stream.
+ * @param labColor
+ * Color to output.
+ *
+ * @return
+ * s with labColor appended.
+ */
+std::ostream&
+operator<<(
+    std::ostream &s,
+    const CIEDE2000::LAB &labColor);
+
+#endif /* GPF_CIEDE2000_H_ */
+

LICENSE

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+The MIT License (MIT)
+
+Copyright (c) 2015 Greg Fiumara
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

Makefile

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+#
+# Makefile
+# Part of http://github.com/gfiumara/CIEDE2000 by Gregory Fiumara.
+# See LICENSE for details.
+#
+
+.PHONY: all clean debug library test
+
+LIBRARY = CIEDE2000
+SOURCE = $(LIBRARY).cpp
+OBJECT = $(SOURCE:%.cpp=%.o)
+DISPOSABLE_FILES = lib$(LIBRARY).so lib$(LIBRARY).dylib $(LIBRARY).dll \
+                   $(OBJECT) test$(OBJECT) test$(LIBRARY)
+DISPOSABLE_DIRS = *dSYM
+OS = $(shell uname)
+
+ifneq ($(findstring MINGW,$(OS)),MINGW)
+WARNING_FLAGS = -Wall -Wextra -pedantic
+PRODUCTION_FLAGS = -O3
+endif
+DEBUG_FLAGS = -g
+TEST_FLAGS = -Wno-unused-parameter
+
+CXXFLAGS += -I. -std=c++11 $(WARNING_FLAGS) $(PRODUCTION_FLAGS)
+
+all: library
+
+debug: CXXFLAGS += $(DEBUG_FLAGS)
+debug: CXXFLAGS := $(filter-out $(PRODUCTION_FLAGS),$(CXXFLAGS))
+debug: all
+
+test$(LIBRARY): LDFLAGS += -L. -lCIEDE2000
+test$(LIBRARY): CXXFLAGS += $(TEST_FLAGS)
+test$(LIBRARY): test$(OBJECT)
+	$(CXX) $^ -o $@ $(LDFLAGS)
+
+test: library test$(LIBRARY)
+
+library: $(LIBRARY).cpp
+ifeq ($(findstring Darwin,$(OS)),Darwin)
+	$(CXX) -dynamiclib $(CXXFLAGS) $^ -o lib$(LIBRARY).dylib
+else
+ifeq ($(findstring MINGW,$(OS)),MINGW)
+	$(CXX) -shared $(CXXFLAGS) $^ -o lib$(LIBRARY).dll
+else
+	$(CXX) -shared $(CXXFLAGS) $^ -o lib$(LIBRARY).so
+endif
+endif
+
+clean:
+	$(RM) $(DISPOSABLE_FILES)
+	$(RM) -r $(DISPOSABLE_DIRS)
+