Added support for OKLab colour spaces

GerHobbelt · Jan 20, 2021 · f5ff4ea · f5ff4ea
1 parent f1bcb56
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diff --git a/DESCRIPTION b/DESCRIPTION
@@ -29,7 +29,7 @@ Description: The encoding of colour can be handled in many different ways, using
 License: MIT + file LICENSE
 Encoding: UTF-8
 SystemRequirements: C++11
-RoxygenNote: 7.0.2
+RoxygenNote: 7.1.1
 URL: https://farver.data-imaginist.com, https://github.com/thomasp85/farver
 BugReports: https://github.com/thomasp85/farver/issues
 Suggests: 

diff --git a/NEWS.md b/NEWS.md
@@ -1,5 +1,7 @@
 # farver (development version)
 
+* Added support for OKLab and OKLch (polar version of OKLab) colour spaces
+
 # farver 2.0.3
 
 * Fixed a bug in colour comparison where the blue channel got ignored 

diff --git a/R/aaa.R b/R/aaa.R
@@ -1,17 +1,19 @@
 colourspaces <- c(
-  "cmy",       # 0
-  "cmyk",      # 1
-  "hsl",       # 2
-  "hsb",       # 3
-  "hsv",       # 4
-  "lab",       # 5
-  "hunterlab", # 6
-  "lch",       # 7
-  "luv",       # 8
-  "rgb",       # 9
-  "xyz",       # 10
-  "yxy",       # 11
-  "hcl"        # 11
+  "cmy",       # 1
+  "cmyk",      # 2
+  "hsl",       # 3
+  "hsb",       # 4
+  "hsv",       # 5
+  "lab",       # 6
+  "hunterlab", # 7
+  "lch",       # 8
+  "luv",       # 9
+  "rgb",       # 10
+  "xyz",       # 11
+  "yxy",       # 12
+  "hcl",       # 13
+  "oklab",     # 14
+  "oklch"      # 15
 )
 colour_dims <- list(
   cmy = c('c', 'm', 'y'),
@@ -26,7 +28,9 @@ colour_dims <- list(
   rgb = c('r', 'g', 'b'),
   xyz = c('x', 'y', 'z'),
   yxy = c('y1', 'x', 'y2'),
-  hcl = c('h', 'c', 'l')
+  hcl = c('h', 'c', 'l'),
+  oklab = c('l', 'a', 'b'),
+  oklch = c('l', 'c', 'h')
 )
 colour_channel_index <- list(
   cmy = c('c' = 1L, 'm' = 2L, 'y' = 3L),
@@ -41,7 +45,9 @@ colour_channel_index <- list(
   rgb = c('r' = 1L, 'g' = 2L, 'b' = 3L),
   xyz = c('x' = 1L, 'y' = 2L, 'z' = 3L),
   yxy = c('y1' = 1L, 'x' = 2L, 'y2' = 3L),
-  hcl = c('h' = 1L, 'c' = 2L, 'l' = 3L)
+  hcl = c('h' = 1L, 'c' = 2L, 'l' = 3L),
+  oklab = c('l' = 1L, 'a' = 2L, 'b' = 3L),
+  oklch = c('l' = 1L, 'c' = 2L, 'h' = 3L)
 )
 distances <- c(
   "euclidean",

diff --git a/R/convert_colour.R b/R/convert_colour.R
@@ -23,8 +23,9 @@
 #' 
 #' @param from,to The input and output colour space. Allowed values are: `"cmy"`, 
 #' `"cmyk"`, `"hsl"`, `"hsb"`, `"hsv"`, `"lab"` (CIE L*ab), `"hunterlab"` 
-#' (Hunter Lab), `"lch"` (CIE Lch(ab) / polarLAB), `"luv"`, `"rgb"` (sRGB), 
-#' `"xyz"`, `"yxy"` (CIE xyY), or `"hcl"` (CIE Lch(uv) / polarLuv)
+#' (Hunter Lab), `"oklab"`, `"lch"` (CIE Lch(ab) / polarLAB), `"luv"`, 
+#' `"rgb"` (sRGB), `"xyz"`, `"yxy"` (CIE xyY), `"hcl"` (CIE Lch(uv) / polarLuv),
+#' or `"oklch"` (Polar form of oklab)
 #' 
 #' @param white_from,white_to The white reference of the from and to colour 
 #' space. Will only have an effect for relative colour spaces such as Lab and 

diff --git a/R/decode.R b/R/decode.R
@@ -14,8 +14,9 @@
 #' assumed 1. If `FALSE` any alpha channel is ignored.
 #' @param to The output colour space. Allowed values are: `"cmy"`, 
 #' `"cmyk"`, `"hsl"`, `"hsb"`, `"hsv"`, `"lab"` (CIE L*ab), `"hunterlab"` 
-#' (Hunter Lab), `"lch"` (CIE Lch(ab) / polarLAB), `"luv"`, `"rgb"` (sRGB), 
-#' `"xyz"`, `"yxy"` (CIE xyY), or `"hcl"` (CIE Lch(uv) / polarLuv) 
+#' (Hunter Lab), `"oklab"`, `"lch"` (CIE Lch(ab) / polarLAB), `"luv"`, 
+#' `"rgb"` (sRGB), `"xyz"`, `"yxy"` (CIE xyY), `"hcl"` (CIE Lch(uv) / polarLuv),
+#' or `"oklch"` (Polar form of oklab)
 #' @param white The white reference of the output colour space. Will only have 
 #' an effect for relative colour spaces such as Lab and luv. Any value accepted 
 #' by [as_white_ref()] allowed.

diff --git a/R/encode.R b/R/encode.R
@@ -11,8 +11,9 @@
 #' of rows in `colour`. If `NULL` or a single `NA` it will be ignored.
 #' @param from The input colour space. Allowed values are: `"cmy"`, 
 #' `"cmyk"`, `"hsl"`, `"hsb"`, `"hsv"`, `"lab"` (CIE L*ab), `"hunterlab"` 
-#' (Hunter Lab), `"lch"` (CIE Lch(ab) / polarLAB), `"luv"`, `"rgb"` (sRGB), 
-#' `"xyz"`, `"yxy"` (CIE xyY), or `"hcl"` (CIE Lch(uv) / polarLuv)
+#' (Hunter Lab), `"oklab"`, `"lch"` (CIE Lch(ab) / polarLAB), `"luv"`, 
+#' `"rgb"` (sRGB), `"xyz"`, `"yxy"` (CIE xyY), `"hcl"` (CIE Lch(uv) / polarLuv),
+#' or `"oklch"` (Polar form of oklab)
 #' @param white The white reference of the input colour space. Will only have an 
 #' effect for relative colour spaces such as Lab and luv. Any value accepted by 
 #' [as_white_ref()] allowed.

diff --git a/R/modify.R b/R/modify.R
@@ -11,8 +11,9 @@
 #' @param value The value to modify with
 #' @param space The colour space the channel pertains to. Allowed values are: 
 #' `"cmy"`, `"cmyk"`, `"hsl"`, `"hsb"`, `"hsv"`, `"lab"` (CIE L*ab), `"hunterlab"` 
-#' (Hunter Lab), `"lch"` (CIE Lch(ab) / polarLAB), `"luv"`, `"rgb"` (sRGB), 
-#' `"xyz"`, `"yxy"` (CIE xyY), or `"hcl"` (CIE Lch(uv) / polarLuv)
+#' (Hunter Lab), `"oklab"` , `"lch"` (CIE Lch(ab) / polarLAB), `"luv"`, 
+#' `"rgb"` (sRGB), `"xyz"`, `"yxy"` (CIE xyY), `"hcl"` (CIE Lch(uv) / polarLuv),
+#' or `"oklch"` (Polar form of oklab)
 #' @param white The white reference of the channel colour space. Will only have 
 #' an effect for relative colour spaces such as Lab and luv. Any value accepted 
 #' by [as_white_ref()] allowed.

diff --git a/man/convert_colour.Rd b/man/convert_colour.Rd
diff --git a/man/decode_colour.Rd b/man/decode_colour.Rd
diff --git a/man/encode_colour.Rd b/man/encode_colour.Rd
diff --git a/man/manip_channel.Rd b/man/manip_channel.Rd
diff --git a/src/ColorSpace.cpp b/src/ColorSpace.cpp
@@ -353,5 +353,55 @@ namespace ColorSpace {
     c = c < 0.0 ? 0.0 : c;
     l = l < 0.0 ? 0.0 : (l > 100.0 ? 100.0 : l);
   }
+
+  OkLab::OkLab() {}
+  OkLab::OkLab(double l, double a, double b) : l(l), a(a), b(b) {
+    valid = R_finite(l) && R_finite(a) && R_finite(b);
+  }
+  OkLab::OkLab(int l, int a, int b) : l(l), a(a), b(b) {
+    valid = !(l == R_NaInt || a == R_NaInt || b == R_NaInt);
+  }
+  void OkLab::Initialize(Rgb *color) {
+    OkLabConverter::ToColorSpace(color, this);
+  }
+  void OkLab::ToRgb(Rgb *color) {
+    OkLabConverter::ToColor(color, this);
+  }
+  void OkLab::Copy(IColorSpace *color) {
+    OkLab *lab = static_cast<OkLab*>(color);
+    lab->l = l;
+    lab->a = a;
+    lab->b = b;
+    lab->valid = valid;
+  }
+  void OkLab::Cap() {
+    if (!valid) return;
+    l = l < 0.0 ? 0.0 : (l > 1.0 ? 1.0 : l);
+  }
+
+OkLch::OkLch() {}
+OkLch::OkLch(double l, double c, double h) : l(l), c(c), h(h) {
+  valid = R_finite(l) && R_finite(c) && R_finite(h);
+}
+OkLch::OkLch(int l, int c, int h) : l(l), c(c), h(h) {
+  valid = !(l == R_NaInt || c == R_NaInt || h == R_NaInt);
+}
+void OkLch::Initialize(Rgb *color) {
+  OkLchConverter::ToColorSpace(color, this);
+}
+void OkLch::ToRgb(Rgb *color) {
+  OkLchConverter::ToColor(color, this);
+}
+void OkLch::Copy(IColorSpace *color) {
+  OkLch *lch = static_cast<OkLch*>(color);
+  lch->l = l;
+  lch->c = c;
+  lch->h = h;
+  lch->valid = valid;
+}
+void OkLch::Cap() {
+  if (!valid) return;
+  l = l < 0.0 ? 0.0 : (l > 1.0 ? 1.0 : l);
+}
 }
 
diff --git a/src/ColorSpace.h b/src/ColorSpace.h
@@ -202,6 +202,32 @@ namespace ColorSpace {
 	  virtual void Cap();
 	};
 
+	struct OkLab : public IColorSpace {
+	  double l, a, b;
+
+	  OkLab();
+	  OkLab(double l, double a, double b);
+	  OkLab(int l, int a, int b);
+
+	  virtual void Initialize(Rgb *color);
+	  virtual void ToRgb(Rgb *color);
+	  virtual void Copy(IColorSpace *color);
+	  virtual void Cap();
+	};
+
+	struct OkLch : public IColorSpace {
+	  double l, c, h;
+
+	  OkLch();
+	  OkLch(double l, double c, double h);
+	  OkLch(int l, int c, int h);
+
+	  virtual void Initialize(Rgb *color);
+	  virtual void ToRgb(Rgb *color);
+	  virtual void Copy(IColorSpace *color);
+	  virtual void Cap();
+	};
+
 }
 
 #endif // COLOR_SPACE_H

diff --git a/src/Conversion.cpp b/src/Conversion.cpp
@@ -563,5 +563,99 @@ namespace ColorSpace {
 
 	  LuvConverter::ToColor(color, &luv);
 	}
+
+	// Using values reported at https://bottosson.github.io/posts/oklab/#converting-from-linear-srgb-to-oklab
+	// instead of going through xyz. This ensures any whitepoint is ignored
+	void OkLabConverter::ToColorSpace(Rgb *color, OkLab *item) {
+	  if (!color->valid) {
+	    item->valid = false;
+	    return;
+	  }
+	  item->valid = true;
+	  double r = color->r / 255.0;
+	  double g = color->g / 255.0;
+	  double b = color->b / 255.0;
+
+	  r = ((r > 0.04045) ? std::pow((r + 0.055) / 1.055, 2.4) : (r / 12.92));
+	  g = ((g > 0.04045) ? std::pow((g + 0.055) / 1.055, 2.4) : (g / 12.92));
+	  b = ((b > 0.04045) ? std::pow((b + 0.055) / 1.055, 2.4) : (b / 12.92));
+
+	  double l = 0.4121656120 * r + 0.5362752080 * g + 0.0514575653 * b;
+	  double m = 0.2118591070 * r + 0.6807189584 * g + 0.1074065790 * b;
+	  double s = 0.0883097947 * r + 0.2818474174 * g + 0.6302613616 * b;
+
+
+	  l = std::cbrt(l);
+	  m = std::cbrt(m);
+	  s = std::cbrt(s);
+
+	  item->l = 0.2104542553 * l + 0.7936177850 * m - 0.0040720468 * s;
+	  item->a = 1.9779984951 * l - 2.4285922050 * m + 0.4505937099 * s;
+	  item->b = 0.0259040371 * l + 0.7827717662 * m - 0.8086757660 * s;
+	}
+	void OkLabConverter::ToColor(Rgb *color, OkLab *item) {
+	  if (!item->valid) {
+	    color->valid = false;
+	    return;
+	  }
+	  color->valid = true;
+	  double l = item->l + 0.3963377774 * item->a + 0.2158037573 * item->b;
+	  double m = item->l - 0.1055613458 * item->a - 0.0638541728 * item->b;
+	  double s = item->l - 0.0894841775 * item->a - 1.2914855480 * item->b;
+
+	  l = l * l * l;
+	  m = m * m * m;
+	  s = s * s * s;
+
+	  double r =  4.0767245293 * l - 3.3072168827 * m + 0.2307590544 * s;
+	  double g = -1.2681437731 * l + 2.6093323231 * m - 0.3411344290 * s;
+	  double b = -0.0041119885 * l - 0.7034763098 * m + 1.7068625689 * s;
+
+	  color->r = ((r > 0.0031308) ? (1.055*std::pow(r, 1 / 2.4) - 0.055) : (12.92*r)) * 255.0;
+	  color->g = ((g > 0.0031308) ? (1.055*std::pow(g, 1 / 2.4) - 0.055) : (12.92*g)) * 255.0;
+	  color->b = ((b > 0.0031308) ? (1.055*std::pow(b, 1 / 2.4) - 0.055) : (12.92*b)) * 255.0;
+	}
+
+	void OkLchConverter::ToColorSpace(Rgb *color, OkLch *item) {
+	  if (!color->valid) {
+	    item->valid = false;
+	    return;
+	  }
+	  item->valid = true;
+	  OkLab lab;
+
+	  OkLabConverter::ToColorSpace(color, &lab);
+	  double l = lab.l;
+	  double c = std::sqrt(lab.a*lab.a + lab.b*lab.b);
+	  double h = std::atan2(lab.b, lab.a);
+
+	  h = h / M_PI * 180;
+	  if (h < 0) {
+	    h += 360;
+	  }
+	  else if (h >= 360) {
+	    h -= 360;
+	  }
+
+	  item->l = l;
+	  item->c = c;
+	  item->h = h;
+	}
+	void OkLchConverter::ToColor(Rgb *color, OkLch *item) {
+	  if (!item->valid) {
+	    color->valid = false;
+	    return;
+	  }
+	  color->valid = true;
+	  OkLab lab;
+
+	  item->h = item->h * M_PI / 180;
+
+	  lab.l = item->l;
+	  lab.a = std::cos(item->h)*item->c;
+	  lab.b = std::sin(item->h)*item->c;
+
+	  OkLabConverter::ToColor(color, &lab);
+	}
 }
 
diff --git a/src/Conversion.h b/src/Conversion.h
@@ -15,6 +15,8 @@ namespace ColorSpace {
 	struct Hsb;
 	struct HunterLab;
 	struct Hcl;
+	struct OkLab;
+	struct OkLch;
 
 	template <typename TColorSpace>
 	struct IConverter {
@@ -116,6 +118,20 @@ namespace ColorSpace {
 	  static void ToColor(Rgb *color, Hcl *item);
 	};
 	typedef IConverter<Hcl> HclConverter;
+
+	template <>
+	struct IConverter<OkLab> {
+	  static void ToColorSpace(Rgb *color, OkLab *item);
+	  static void ToColor(Rgb *color, OkLab *item);
+	};
+	typedef IConverter<OkLab> OkLabConverter;
+
+	template <>
+	struct IConverter<OkLch> {
+	  static void ToColorSpace(Rgb *color, OkLch *item);
+	  static void ToColor(Rgb *color, OkLch *item);
+	};
+	typedef IConverter<OkLch> OkLchConverter;
 }
 
 #endif // RGB_CONVERTER_H