diff --git a/src/ImageProcessor/Colors/ColorTransforms.cs b/src/ImageProcessor/Colors/ColorTransforms.cs
index 7643db0b1..e085f35e8 100644
--- a/src/ImageProcessor/Colors/ColorTransforms.cs
+++ b/src/ImageProcessor/Colors/ColorTransforms.cs
@@ -192,11 +192,16 @@ namespace ImageProcessor
float y3 = y * y * y;
float z3 = z * z * z;
- y = (y3 > 0.008856F) ? y3 : (y - 16F / 116F) / 7.787F;
x = (x3 > 0.008856F) ? x3 : (x - 16F / 116F) / 7.787F;
+ y = (cieLabColor.L > 0.008856F * 903.3F) ? y3 : (cieLabColor.L / 903.3F);
z = (z3 > 0.008856F) ? z3 : (z - 16F / 116F) / 7.787F;
- // Then XYZ to RGB
+ x *= 0.95047F;
+ //y *= 1F;
+ z *= 1.08883F;
+
+ // Then XYZ to RGB (multiplication by 100 was done above already)
+
float r = (x * 3.2406F) + (y * -1.5372F) + (z * -0.4986F);
float g = (x * -0.9689F) + (y * 1.8758F) + (z * 0.0415F);
float b = (x * 0.0557F) + (y * -0.2040F) + (z * 1.0570F);
diff --git a/src/ImageProcessor/Colors/Colorspaces/CieLab.cs b/src/ImageProcessor/Colors/Colorspaces/CieLab.cs
index 567937edb..6098d40f8 100644
--- a/src/ImageProcessor/Colors/Colorspaces/CieLab.cs
+++ b/src/ImageProcessor/Colors/Colorspaces/CieLab.cs
@@ -86,20 +86,16 @@ namespace ImageProcessor
float y = (color.R * 0.2126F) + (color.G * 0.7152F) + (color.B * 0.0722F);
float z = (color.R * 0.0193F) + (color.G * 0.1192F) + (color.B * 0.9505F);
- x *= 100F;
- y *= 100F;
- z *= 100F;
-
// Now to LAB
- x /= 95.047F;
- y /= 100F;
- z /= 108.883F;
+ x /= 0.95047F;
+ //y /= 1F;
+ z /= 1.08883F;
- x = x > 0.008856 ? (float) Math.Pow(x, 1F / 3F) : (7.787F * x) + (16F / 116F);
- y = y > 0.008856 ? (float) Math.Pow(y, 1F / 3F) : (7.787F * y) + (16F / 116F);
- z = z > 0.008856 ? (float) Math.Pow(z, 1F / 3F) : (7.787F * z) + (16F / 116F);
+ x = x > 0.008856F ? (float) Math.Pow(x, 1F / 3F) : (903.3F * x + 16F) / 116F;
+ y = y > 0.008856F ? (float) Math.Pow(y, 1F / 3F) : (903.3F * y + 16F) / 116F;
+ z = z > 0.008856F ? (float) Math.Pow(z, 1F / 3F) : (903.3F * z + 16F) / 116F;
- float l = (116F * y) - 16F;
+ float l = Math.Max(0, (116F * y) - 16F);
float a = 500F * (x - y);
float b = 200F * (y - z);
diff --git a/tests/ImageProcessor.Tests/Colors/ColorConversionTests.cs b/tests/ImageProcessor.Tests/Colors/ColorConversionTests.cs
index e68a7e74e..b219cd123 100644
--- a/tests/ImageProcessor.Tests/Colors/ColorConversionTests.cs
+++ b/tests/ImageProcessor.Tests/Colors/ColorConversionTests.cs
@@ -339,9 +339,6 @@ namespace ImageProcessor.Tests
/// Tests the implicit conversion from to .
/// Comparison values obtained from
/// http://colormine.org/convert/rgb-to-lab
- /// http://au.mathworks.com/help/images/ref/rgb2lab.html
- /// http://www.colorhexa.com/00ffff
- /// L seems to match quite well, A and B tend to drift from the converter results a bit more
///
[Fact]
public void ColorToCieLab()
@@ -350,35 +347,37 @@ namespace ImageProcessor.Tests
Color color = new Color(1, 1, 1);
CieLab cielab = color;
- Assert.Equal(100, cielab.L, 1);
- Assert.Equal(0, cielab.A, 1);
- Assert.Equal(0, cielab.B, 1);
+ Assert.Equal(100, cielab.L, 3);
+ Assert.Equal(0.005, cielab.A, 3);
+ Assert.Equal(-0.010, cielab.B, 3);
// Black
Color color2 = new Color(0, 0, 0);
CieLab cielab2 = color2;
- Assert.Equal(0, cielab2.L, 1);
- Assert.Equal(0, cielab2.A, 1);
- Assert.Equal(0, cielab2.B, 1);
+ Assert.Equal(0, cielab2.L, 3);
+ Assert.Equal(0, cielab2.A, 3);
+ Assert.Equal(0, cielab2.B, 3);
//// Grey
Color color3 = new Color(128 / 255f, 128 / 255f, 128 / 255f);
CieLab cielab3 = color3;
- Assert.Equal(53.6, cielab3.L, 1);
- Assert.Equal(0, cielab3.A, 1);
- Assert.Equal(0, cielab3.B, 1);
+ Assert.Equal(53.585, cielab3.L, 3);
+ Assert.Equal(0.003, cielab3.A, 3);
+ Assert.Equal(-0.006, cielab3.B, 3);
//// Cyan
Color color4 = new Color(0, 1, 1);
CieLab cielab4 = color4;
- Assert.Equal(91.1, cielab4.L, 1);
- Assert.Equal(-48.1, cielab4.A, 1);
- Assert.Equal(-14.1, cielab4.B, 1);
+ Assert.Equal(91.117, cielab4.L, 3);
+ Assert.Equal(-48.080, cielab4.A, 3);
+ Assert.Equal(-14.138, cielab4.B, 3);
}
///
/// Tests the implicit conversion from to .
///
+ /// Comparison values obtained from
+ /// http://colormine.org/convert/rgb-to-lab
[Fact]
public void CieLabToColor()
{
@@ -386,25 +385,25 @@ namespace ImageProcessor.Tests
CieLab cielab = new CieLab(36.5492f, 33.3173f, -12.0615f);
Color color = cielab;
- Assert.Equal(color.R, 128 / 255f, 1);
- Assert.Equal(color.G, 64 / 255f, 2);
- Assert.Equal(color.B, 106 / 255f, 1);
+ Assert.Equal(color.R, 128 / 255f, 3);
+ Assert.Equal(color.G, 64 / 255f, 3);
+ Assert.Equal(color.B, 106 / 255f, 3);
// Ochre
CieLab cielab2 = new CieLab(58.1758f, 27.3399f, 56.8240f);
Color color2 = cielab2;
- Assert.Equal(color2.R, 204 / 255f, 1);
- Assert.Equal(color2.G, 119 / 255f, 2);
- Assert.Equal(color2.B, 34 / 255f, 1);
+ Assert.Equal(color2.R, 204 / 255f, 3);
+ Assert.Equal(color2.G, 119 / 255f, 3);
+ Assert.Equal(color2.B, 34 / 255f, 3);
//// White
CieLab cielab3 = new CieLab(0, 0, 0);
Color color3 = cielab3;
- Assert.Equal(color3.R, 0f, 1);
- Assert.Equal(color3.G, 0f, 1);
- Assert.Equal(color3.B, 0f, 1);
+ Assert.Equal(color3.R, 0f, 3);
+ Assert.Equal(color3.G, 0f, 3);
+ Assert.Equal(color3.B, 0f, 3);
//// Check others.
Random random = new Random(0);