Color.GetBrightness Method

public void KnownColorBrightnessExample2(PaintEventArgs e)
{
    Graphics     g = e.Graphics;

    // Color structures. One is a variable used for temporary storage. The other 
    // is a constant used for comparisons.
    Color   someColor = Color.FromArgb(0);
    Color   redShade = Color.FromArgb(255, 200, 0, 100);

    // Array to store KnownColor values that match the brightness of the 
    // redShade color.
    KnownColor[]  colorMatches = new KnownColor[15];

    // Number of matches found. 
    int  count = 0;   

    // Iterate through the KnownColor enums until 15 matches are found. 
    for (KnownColor enumValue = 0;
        enumValue <= KnownColor.YellowGreen && count < 15; enumValue++)
    {
        someColor = Color.FromKnownColor(enumValue);
        if (someColor.GetBrightness() == redShade.GetBrightness())
            colorMatches[count++] = enumValue;
    }

    // display the redShade color and its argb value.
    SolidBrush  myBrush1 = new SolidBrush(redShade);
    Font        myFont = new Font("Arial", 12);
    int         x = 20;
    int         y = 20;
    someColor = redShade;
    g.FillRectangle(myBrush1, x, y, 100, 30);
    g.DrawString(someColor.ToString(), myFont, Brushes.Black, x + 120, y);

    // Iterate through the matches that were found and display each color that 
    // corresponds with the enum value in the array. also display the name of 
    // The KnownColor. 
    for (int i = 0; i < count; i++)
    {
        y += 40;
        someColor = Color.FromKnownColor(colorMatches[i]);
        myBrush1.Color = someColor;
        g.FillRectangle(myBrush1, x, y, 100, 30);
        g.DrawString(someColor.ToString(), myFont, Brushes.Black, x + 120, y);
    }
}