using System;

using System.Drawing;

public class Program

{

    public static void Main()

    {

        var originalColor = ColorTranslator.FromHtml("#01aeb9");

        var color = Color.Purple;

        var changedColor = FromAhsb(originalColor.A, color.GetHue(), originalColor.GetSaturation(), originalColor.GetBrightness());

        Console.WriteLine(ColorTranslator.ToHtml(changedColor));

    }

    /// <summary>

    /// Creates a Color from alpha, hue, saturation and brightness.

    /// </summary>

    /// <param name="alpha">The alpha channel value.</param>

    /// <param name="hue">The hue value.</param>

    /// <param name="saturation">The saturation value.</param>

    /// <param name="brightness">The brightness value.</param>

    /// <returns>A Color with the given values.</returns>

    public static Color FromAhsb(int alpha, float hue, float saturation, float brightness)

    {

​

        if (0 > alpha || 255 < alpha)

        {

            throw new ArgumentOutOfRangeException("alpha", alpha,

              "Value must be within a range of 0 - 255.");

        }

        if (0f > hue || 360f < hue)

        {

            throw new ArgumentOutOfRangeException("hue", hue,

              "Value must be within a range of 0 - 360.");

        }

        if (0f > saturation || 1f < saturation)

        {

            throw new ArgumentOutOfRangeException("saturation", saturation,

              "Value must be within a range of 0 - 1.");

        }

        if (0f > brightness || 1f < brightness)

        {

            throw new ArgumentOutOfRangeException("brightness", brightness,

              "Value must be within a range of 0 - 1.");

        }

​

        if (0 == saturation)

        {

            return Color.FromArgb(alpha, Convert.ToInt32(brightness * 255),

              Convert.ToInt32(brightness * 255), Convert.ToInt32(brightness * 255));

        }

​

        float fMax, fMid, fMin;

        int iSextant, iMax, iMid, iMin;

​

        if (0.5 < brightness)

        {

            fMax = brightness - (brightness * saturation) + saturation;

            fMin = brightness + (brightness * saturation) - saturation;

        }

        else

        {

            fMax = brightness + (brightness * saturation);

            fMin = brightness - (brightness * saturation);

        }

​

        iSextant = (int)Math.Floor(hue / 60f);

        if (300f <= hue)

        {

            hue -= 360f;

        }

        hue /= 60f;

        hue -= 2f * (float)Math.Floor(((iSextant + 1f) % 6f) / 2f);

        if (0 == iSextant % 2)

        {

            fMid = hue * (fMax - fMin) + fMin;

        }

        else

        {

            fMid = fMin - hue * (fMax - fMin);

        }

​

        iMax = Convert.ToInt32(fMax * 255);

        iMid = Convert.ToInt32(fMid * 255);

        iMin = Convert.ToInt32(fMin * 255);

​

        switch (iSextant)

        {

            case 1:

                return Color.FromArgb(alpha, iMid, iMax, iMin);

            case 2:

                return Color.FromArgb(alpha, iMin, iMax, iMid);

            case 3:

                return Color.FromArgb(alpha, iMin, iMid, iMax);

            case 4:

                return Color.FromArgb(alpha, iMid, iMin, iMax);

            case 5:

                return Color.FromArgb(alpha, iMax, iMin, iMid);

            default:

                return Color.FromArgb(alpha, iMax, iMid, iMin);

        }

    }

}