conversion

CMakeLists.txt

@@ -6,8 +6,8 @@ project(color)
 set(CMAKE_CXX_STANDARD 11)
 set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
 
-add_library(CIEDE2000 SHARED src/CIEDE2000.cpp)
-target_include_directories(CIEDE2000 PUBLIC include)
+add_library(color SHARED src/color.cpp src/conversion.cpp src/CIEDE2000.cpp)
+target_include_directories(color PUBLIC include)
 
 add_executable(testCIEDE2000 test/testCIEDE2000.cpp)
-target_link_libraries(testCIEDE2000 CIEDE2000)
+target_link_libraries(testCIEDE2000 color)

include/color.h

@@ -13,22 +13,13 @@
 #define M_PI 3.14159265358979323846264338327950288 /* pi */
 #endif
 
-/** Namespace containing all necessary objects and methods for color */
 namespace color {
-/***********************************************************************
- * 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;
 
 /** A color in CIEXYZ colorspace */
@@ -37,7 +28,6 @@ struct XYZ {
   double y;
   double z;
 };
-/** Convenience definition for struct XYZ */
 using XYZ = struct XYZ;
 
 /** A color in CIERGB colorspace */
@@ -46,13 +36,8 @@ struct RGB {
   double g;
   double b;
 };
-/** Convenience definition for struct RGB */
 using RGB = struct RGB;
 
-/***********************************************************************
- * Operations.
- **********************************************************************/
-
 /**
  * @brief
  * Obtain Delta-E 2000 value.
@@ -72,51 +57,19 @@ using RGB = struct RGB;
  */
 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.
- ******************************************************************************/
+RGB XYZtoRGB(const XYZ &xyz);
+XYZ LABtoXYZ(const LAB &lab);
+RGB LABtoRGB(const LAB &lab);
+
+bool offRGB(const LAB &lab);
 
 } // namespace color
-/**
- * @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 color::LAB &labColor);
+std::ostream &operator<<(std::ostream &s, const color::XYZ &labColor);
+std::ostream &operator<<(std::ostream &s, const color::RGB &labColor);
 
 #endif /* GPF_COLOR_H_ */

include/constant.h

@@ -0,0 +1,22 @@
+#ifndef ICC_CONSTANT_H_
+#define ICC_CONSTANT_H_
+
+namespace color {
+/* ICC's PCS illuminant */
+const double PCS_X = 31595. / 32768.;
+const double PCS_Y = 1;
+const double PCS_Z = 27030. / 32768.;
+
+/* Macbook's LCD color profile for XYZ -> RGB */
+const double A11 = 3.98875596;
+const double A12 = -2.41598659;
+const double A13 = -0.52021109;
+const double A21 = -1.40052984;
+const double A22 = 2.37728799;
+const double A23 = -0.03294208;
+const double A31 = -0.03269638;
+const double A32 = -0.18259425;
+const double A33 = 1.4716528;
+} // namespace color
+
+#endif /* ICC_CONSTANT_H_ */

src/CIEDE2000.cpp

@@ -147,13 +147,4 @@ double color::CIEDE2000(const LAB &lab1, const LAB &lab2) {
            (R_T * (deltaCPrime / (k_C * S_C)) * (deltaHPrime / (k_H * S_H))));
 
   return (deltaE);
-}
-
-/*******************************************************************************
- * Operators.
- ******************************************************************************/
-
-std::ostream &operator<<(std::ostream &s, const color::LAB &labColor) {
-  return (s << "CIELAB(" << labColor.l << "," << labColor.a << "," << labColor.b
-            << ")");
-}
+}

src/color.cpp

@@ -0,0 +1,13 @@
+#include <color.h>
+
+std::ostream &operator<<(std::ostream &s, const color::LAB &lab) {
+  return (s << "LAB(" << lab.l << "," << lab.a << "," << lab.b << ")");
+}
+
+std::ostream &operator<<(std::ostream &s, const color::XYZ &xyz) {
+  return (s << "XYZ(" << xyz.x << "," << xyz.y << "," << xyz.z << ")");
+}
+
+std::ostream &operator<<(std::ostream &s, const color::RGB &rgb) {
+  return (s << "RGB(" << rgb.r << "," << rgb.g << "," << rgb.b << ")");
+}

src/conversion.cpp

@@ -0,0 +1,47 @@
+#define _USE_MATH_DEFINES
+#include <cmath>
+#include <color.h>
+#include <constant.h>
+
+namespace color {
+double sgn(double val) { return (0. < val) - (val < 0.); }
+constexpr inline double pow3(double x) { return x * x * x; }
+
+RGB XYZtoRGB(const XYZ &xyz) {
+  double r = xyz.x * A11 + xyz.y * A12 + xyz.z * A13;
+  double g = xyz.x * A21 + xyz.y * A22 + xyz.z * A23;
+  double b = xyz.x * A31 + xyz.y * A32 + xyz.z * A33;
+
+  r = ((abs(r) > 0.0031308) ? sgn(r) * (1.055 * pow(abs(r), 1 / 2.4) - 0.055) : (12.92 * r));
+  g = ((abs(g) > 0.0031308) ? sgn(g) * (1.055 * pow(abs(g), 1 / 2.4) - 0.055) : (12.92 * g));
+  b = ((abs(b) > 0.0031308) ? sgn(b) * (1.055 * pow(abs(b), 1 / 2.4) - 0.055) : (12.92 * b));
+
+  return RGB{r, g, b};
+}
+
+XYZ LABtoXYZ(const LAB &lab) {
+  double y = (lab.l + 16.0) / 116.0;
+  double x = lab.a / 500.0 + y;
+  double z = y - lab.b / 200.0;
+
+  double x3 = pow3(x);
+  double y3 = pow3(y);
+  double z3 = pow3(z);
+
+  x = ((x3 > 0.008856) ? x3 : ((x - 16.0 / 116.0) / 7.787)) * PCS_X;
+  y = ((y3 > 0.008856) ? y3 : ((y - 16.0 / 116.0) / 7.787)) * PCS_Y;
+  z = ((z3 > 0.008856) ? z3 : ((z - 16.0 / 116.0) / 7.787)) * PCS_Z;
+
+  return XYZ{x, y, z};
+}
+
+RGB LABtoRGB(const LAB &lab) { return XYZtoRGB(LABtoXYZ(lab)); }
+
+bool offRGB(const LAB &lab) {
+  const RGB rgb{LABtoRGB(lab)};
+
+  return rgb.r >= 0 && rgb.r <= 1 && rgb.g >= 0 && rgb.g <= 1 && rgb.b >= 0 &&
+         rgb.b <= 1;
+}
+
+} // namespace color

test/testCIEDE2000.cpp

@@ -4,6 +4,7 @@
  * See LICENSE for details.
  */
 
+#include <cmath>
 #include <iostream>
 #include <string>
 #include <vector>
@@ -23,11 +24,38 @@ int main(int argc, char *argv[]) { return (testcolor()); }
 
 int testcolor() {
   color::LAB lab1, lab2;
-  double expectedResult, myResult;
+  color::RGB rgb1, rgb_expected;
   unsigned int line = 1;
+  std::vector<bool> passFail;
+
+  lab1 = {100, 0, 0};
+  rgb1 = color::LABtoRGB(lab1);
+  rgb_expected = {1, 1, 1};
+
+  passFail.push_back(std::abs(rgb1.r - rgb_expected.r) < 1e-3);
+  std::cout << line << ": " << rgb1.r << " vs " << rgb_expected.r << '\t'
+            << (passFail[line - 1] ? "PASS" : "FAIL") << std::endl;
+  ++line;
+
+  passFail.push_back(std::abs(rgb1.g - rgb_expected.g) < 1e-3);
+  std::cout << line << ": " << rgb1.g << " vs " << rgb_expected.g << '\t'
+            << (passFail[line - 1] ? "PASS" : "FAIL") << std::endl;
+  ++line;
+
+  passFail.push_back(std::abs(rgb1.b - rgb_expected.b) < 1e-3);
+  std::cout << line << ": " << rgb1.b << " vs " << rgb_expected.b << '\t'
+            << (passFail[line - 1] ? "PASS" : "FAIL") << std::endl;
+  ++line;
+
+  std::cout << color::LABtoRGB(color::LAB{50, 0, 0}) << std::endl;
+  std::cout << color::LABtoRGB(color::LAB{50, 1000, 0}) << std::endl;
+  std::cout << color::LABtoRGB(color::LAB{50, -1000, 0}) << std::endl;
+  std::cout << color::LABtoRGB(color::LAB{50, 0, 1000}) << std::endl;
+  std::cout << color::LABtoRGB(color::LAB{50, 0, -1000}) << std::endl;
+
+  double expectedResult, myResult;
   char myBuffer[64], expectedBuffer[64];
   std::string myStr, expectedStr;
-  std::vector<bool> passFail;
 
   lab1 = {50.0000, 2.6772, -79.7751};
   lab2 = {50.0000, 0.0000, -82.7485};