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Add RGB-HSV Conversion (#216)
* add RGBHSVConversion.cs * add RGBHSVConversionTest.cs * Update DIRECTORY.md Co-authored-by: Andrii Siriak <siryaka@gmail.com>
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‎Algorithms.Tests/Other/RGBHSVConversionTest.cs‎

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using System;
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using NUnit.Framework;
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using FluentAssertions;
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namespace Algorithms.Other
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{
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public static class RgbHsvConversionTest
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{
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[Test]
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public static void HueOutOfRange_ThrowsArgumentOutOfRangeException()
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{
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Action act = () => Algorithms.Other.RgbHsvConversion.HsvToRgb(400, 0, 0);
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act.Should().Throw<ArgumentOutOfRangeException>();
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}
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[Test]
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public static void SaturationOutOfRange_ThrowsArgumentOutOfRangeException()
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{
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Action act = () => Algorithms.Other.RgbHsvConversion.HsvToRgb(0, 2, 0);
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act.Should().Throw<ArgumentOutOfRangeException>();
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}
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[Test]
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public static void ValueOutOfRange_ThrowsArgumentOutOfRangeException()
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{
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Action act = () => Algorithms.Other.RgbHsvConversion.HsvToRgb(0, 0, 2);
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act.Should().Throw<ArgumentOutOfRangeException>();
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}
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// expected RGB-values taken from https://www.rapidtables.com/convert/color/hsv-to-rgb.html
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[Test]
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[TestCase(0, 0, 0, 0, 0, 0)]
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[TestCase(0, 0, 1, 255, 255, 255)]
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[TestCase(0, 1, 1, 255, 0, 0)]
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[TestCase(60, 1, 1, 255, 255, 0)]
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[TestCase(120, 1, 1, 0, 255, 0)]
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[TestCase(240, 1, 1, 0, 0, 255)]
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[TestCase(300, 1, 1, 255, 0, 255)]
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[TestCase(180, 0.5, 0.5, 64, 128, 128)]
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[TestCase(234, 0.14, 0.88, 193, 196, 224)]
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[TestCase(330, 0.75, 0.5, 128, 32, 80)]
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public static void TestRgbOutput(
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double hue,
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double saturation,
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double value,
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byte expectedRed,
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byte exptectedGreen,
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byte exptectedBlue)
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{
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var rgb = Algorithms.Other.RgbHsvConversion.HsvToRgb(hue, saturation, value);
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rgb.Item1.Should().Be(expectedRed);
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rgb.Item2.Should().Be(exptectedGreen);
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rgb.Item3.Should().Be(exptectedBlue);
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}
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// Parameters of test-cases for TestRGBOutput reversed
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[Test]
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[TestCase(0, 0, 0, 0, 0, 0)]
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[TestCase(255, 255, 255, 0, 0, 1)]
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[TestCase(255, 0, 0, 0, 1, 1)]
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[TestCase(255, 255, 0, 60, 1, 1)]
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[TestCase(0, 255, 0, 120, 1, 1)]
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[TestCase(0, 0, 255, 240, 1, 1)]
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[TestCase(255, 0, 255, 300, 1, 1)]
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[TestCase(64, 128, 128, 180, 0.5, 0.5)]
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[TestCase(193, 196, 224, 234, 0.14, 0.88)]
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[TestCase(128, 32, 80, 330, 0.75, 0.5)]
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public static void TestHsvOutput(
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byte red,
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byte green,
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byte blue,
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double expectedHue,
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double expectedSaturation,
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double expectedValue)
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{
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var hsv = Algorithms.Other.RgbHsvConversion.RgbToHsv(red, green, blue);
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// approximate-assertions needed because of small deviations due to converting between byte-values and double-values.
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hsv.Item1.Should().BeApproximately(expectedHue, 0.2);
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hsv.Item2.Should().BeApproximately(expectedSaturation, 0.002);
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hsv.Item3.Should().BeApproximately(expectedValue, 0.002);
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}
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}
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}

‎Algorithms/Other/RGBHSVConversion.cs‎

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using System;
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using System.Drawing;
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namespace Algorithms.Other
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{
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/// <summary>
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/// The RGB color model is an additive color model in which red, green, and
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/// blue light are added together in various ways to reproduce a broad array of
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/// colors. The name of the model comes from the initials of the three additive
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/// primary colors, red, green, and blue. Meanwhile, the HSV representation
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/// models how colors appear under light. In it, colors are represented using
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/// three components: hue, saturation and (brightness-)value. This class
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/// provides methods for converting colors from one representation to the other.
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/// (description adapted from https://en.wikipedia.org/wiki/RGB_color_model and https://en.wikipedia.org/wiki/HSL_and_HSV).
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/// </summary>
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public static class RgbHsvConversion
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{
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/// <summary>
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/// Conversion from the HSV-representation to the RGB-representation.
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/// </summary>
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/// <param name="hue">Hue of the color.</param>
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/// <param name="saturation">Saturation of the color.</param>
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/// <param name="value">Brightness-value of the color.</param>
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/// <returns>The tuple of RGB-components.</returns>
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public static (byte red, byte green, byte blue) HsvToRgb(
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double hue,
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double saturation,
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double value)
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{
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if (hue < 0 || hue > 360)
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{
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throw new ArgumentOutOfRangeException(nameof(hue), $"{nameof(hue)} should be between 0 and 360");
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}
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if (saturation < 0 || saturation > 1)
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{
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throw new ArgumentOutOfRangeException(nameof(saturation), $"{nameof(saturation)} should be between 0 and 1");
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}
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if (value < 0 || value > 1)
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{
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throw new ArgumentOutOfRangeException(nameof(value), $"{nameof(value)} should be between 0 and 1");
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}
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double chroma = value * saturation;
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double hueSection = hue / 60;
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double secondLargestComponent = chroma * (1 - Math.Abs(hueSection % 2 - 1));
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double matchValue = value - chroma;
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return GetRgbBySection(hueSection, chroma, matchValue, secondLargestComponent);
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}
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/// <summary>
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/// Conversion from the RGB-representation to the HSV-representation.
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/// </summary>
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/// <param name="red">Red-component of the color.</param>
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/// <param name="green">Green-component of the color.</param>
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/// <param name="blue">Blue-component of the color.</param>
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/// <returns>The tuple of HSV-components.</returns>
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public static (double hue, double saturation, double value) RgbToHsv(
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byte red,
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byte green,
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byte blue)
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{
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double dRed = (double)red / 255;
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double dGreen = (double)green / 255;
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double dBlue = (double)blue / 255;
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double value = Math.Max(Math.Max(dRed, dGreen), dBlue);
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double chroma = value - Math.Min(Math.Min(dRed, dGreen), dBlue);
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double saturation = value.Equals(0) ? 0 : chroma / value;
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double hue;
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if (chroma.Equals(0))
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{
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hue = 0;
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}
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else if (value.Equals(dRed))
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{
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hue = 60 * (0 + (dGreen - dBlue) / chroma);
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}
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else if (value.Equals(dGreen))
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{
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hue = 60 * (2 + (dBlue - dRed) / chroma);
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}
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else
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{
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hue = 60 * (4 + (dRed - dGreen) / chroma);
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}
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hue = (hue + 360) % 360;
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return (hue, saturation, value);
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}
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private static (byte red, byte green, byte blue) GetRgbBySection(double hueSection, double chroma, double matchValue, double secondLargestComponent)
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{
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byte red;
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byte green;
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byte blue;
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if (hueSection >= 0 && hueSection <= 1)
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{
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red = ConvertToByte(chroma + matchValue);
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green = ConvertToByte(secondLargestComponent + matchValue);
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blue = ConvertToByte(matchValue);
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}
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else if (hueSection > 1 && hueSection <= 2)
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{
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red = ConvertToByte(secondLargestComponent + matchValue);
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green = ConvertToByte(chroma + matchValue);
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blue = ConvertToByte(matchValue);
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}
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else if (hueSection > 2 && hueSection <= 3)
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{
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red = ConvertToByte(matchValue);
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green = ConvertToByte(chroma + matchValue);
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blue = ConvertToByte(secondLargestComponent + matchValue);
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}
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else if (hueSection > 3 && hueSection <= 4)
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{
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red = ConvertToByte(matchValue);
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green = ConvertToByte(secondLargestComponent + matchValue);
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blue = ConvertToByte(chroma + matchValue);
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}
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else if (hueSection > 4 && hueSection <= 5)
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{
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red = ConvertToByte(secondLargestComponent + matchValue);
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green = ConvertToByte(matchValue);
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blue = ConvertToByte(chroma + matchValue);
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}
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else
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{
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red = ConvertToByte(chroma + matchValue);
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green = ConvertToByte(matchValue);
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blue = ConvertToByte(secondLargestComponent + matchValue);
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}
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return (red, green, blue);
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}
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private static byte ConvertToByte(double input)
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{
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return (byte)Math.Round(255 * input);
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}
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}
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}

‎DIRECTORY.md‎

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* [Fermat Prime Checker](https://github.com/TheAlgorithms/C-Sharp/blob/master/Algorithms/Other/FermatPrimeChecker.cs)
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* [Sieve of Eratosthenes](https://github.com/TheAlgorithms/C-Sharp/blob/master/Algorithms/Other/SieveOfEratosthenes.cs)
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* [Luhn](https://github.com/TheAlgorithms/C-Sharp/blob/master/Algorithms/Other/Luhn.cs)
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* [Mandelbrot](./Algorithms/Other/Mandelbrot.cs)
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* [Koch Snowflake](./Algorithms/Other/KochSnowflake.cs)
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* [RGB-HSV Conversion](./Algorithms/Other/RGBHSVConversion.cs)
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## Problems
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* [Stable Marriage](https://github.com/TheAlgorithms/C-Sharp/blob/master/Algorithms/Problems/StableMarriage/GaleShapley.cs)
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* [N-Queens](https://github.com/TheAlgorithms/C-Sharp/blob/master/Algorithms/Problems/NQueens/BacktrackingNQueensSolver.cs)

‎README.md‎

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* [Luhn](./Algorithms/Other/Luhn.cs)
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* [Mandelbrot](./Algorithms/Other/Mandelbrot.cs)
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* [Koch Snowflake](./Algorithms/Other/KochSnowflake.cs)
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* [RGB-HSV Conversion](./Algorithms/Other/RGBHSVConversion.cs)
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* [Problems](./Algorithms/Problems/)
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* [Stable Marriage](./Algorithms/Problems/StableMarriage)
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* [Gale-Shapley](./Algorithms/Problems/StableMarriage/GaleShapley.cs)

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