How to make different types of colors and color ramps

In this topic

• About making different types of colors and color ramps
• Making different types of colors
  • RGB color model
  • CMYK color model
  • HSV color model
  • HLS color model
• Color ramps

About making different types of colors and color ramps

Making different types of colors

RGB color model

• When red, green, and blue rays of light coincide, white light is created. The RGB color model is therefore termed "additive", as adding the components together creates light.
• An equal triad of fully saturated colors (255,255,255) illuminate white; and, conversely, 0 values illuminate nothing or black.
• Equal triads between 0 and 100 produce pure gray shades.

Public Shared Function MakeRGBColor(ByVal R As Byte, ByVal G As Byte, ByVal B As Byte) As ESRI.ArcGIS.Display.IRgbColor
Dim RgbClr As ESRI.ArcGIS.Display.RgbColor=New ESRI.ArcGIS.Display.RgbColorClass
With RgbClr
    .Red=R
    .Green=G
    .Blue=B
End With
Return RgbClr
End Function

public static ESRI.ArcGIS.Display.IRgbColor MakeRGBColor(byte R, byte G, byte B)
{
    ESRI.ArcGIS.Display.RgbColor RgbClr=new ESRI.ArcGIS.Display.RgbColorClass();
    RgbClr.Red=R;
    RgbClr.Green=G;
    RgbClr.Blue=B;
    return RgbClr;
}

CMYK color model

• CMYK is the industry standard color model for electronic publishing processes including offset-printing with color plates.
• During the printing process, the ink coverage is controlled by the size of the dot or halftone screen percentage that is specified for each of the four process colors.

Public Shared Function MakeCmykColor(ByVal C As Byte, ByVal M As Byte, ByVal Y As Byte, ByVal k As Byte) As ESRI.ArcGIS.Display.ICmykColor
Dim CmykClr As ESRI.ArcGIS.Display.CmykColor=New ESRI.ArcGIS.Display.CmykColorClass
With CmykClr
    .Cyan=C
    .Magenta=M
    .Yellow=Y
    .Black=k
End With
Return CmykClr
End Function

public static ESRI.ArcGIS.Display.ICmykColor MakeCmykColor(byte C, byte M, byte Y,
    byte k)
{
    ESRI.ArcGIS.Display.CmykColor CmykClr=new ESRI.ArcGIS.Display.CmykColorClass();
    CmykClr.Cyan=C;
    CmykClr.Magenta=M;
    CmykClr.Yellow=Y;
    CmykClr.Black=k;
    return CmykClr;
}

HSV color model

• When the saturation is 100, the color is fully saturated.
• When the saturation is 0, the color is a pure gray shade of the value specified.
• When the value is 100 and any saturation is specified, a color tint is produced.
• When the value is less than 100 and a saturation is specified, a shade is produced.
• When the value is 0, the color is black.

Public Shared Function MakeHSVColor(ByVal H As Byte, ByVal S As Byte, ByVal V As Byte) As ESRI.ArcGIS.Display.IHsvColor
Dim HsvClr As ESRI.ArcGIS.Display.HsvColor=New ESRI.ArcGIS.Display.HsvColorClass
With HsvClr
    .Hue=H
    .Saturation=S
    .Value=V
End With
Return HsvClr
End Function

public static ESRI.ArcGIS.Display.IHsvColor MakeHSVColor(byte H, byte S, byte V)
{
    ESRI.ArcGIS.Display.HsvColor HsvClr=new ESRI.ArcGIS.Display.HsvColorClass();
    HsvClr.Hue=H;
    HsvClr.Saturation=S;
    HsvClr.Value=V;
    return HsvClr;
}

HLS color model

• When lightness is 0, the color is black.
• When lightness is 100, the color is white.
• When lightness is greater than 50, a color tint is produced.
• When lightness is less than 50, a color shade is produced.
• When saturation is 100, the color is fully saturated. 
• When saturation is 0, the color is a pure gray shade of the specified lightness.

Public Shared Function MakeHLSColor(ByVal H As Byte, ByVal L As Byte, ByVal S As Byte) As ESRI.ArcGIS.Display.IHlsColor
Dim HlsClr As ESRI.ArcGIS.Display.HlsColor=New ESRI.ArcGIS.Display.HlsColorClass
With HlsClr
    .Hue=H
    .Lightness=L
    .Saturation=S
End With
Return HlsClr
End Function

public static ESRI.ArcGIS.Display.IHlsColor MakeHLSColor(byte H, byte L, byte S)
{
    ESRI.ArcGIS.Display.HlsColor HlsClr=new ESRI.ArcGIS.Display.HlsColorClass();
    HlsClr.Hue=H;
    HlsClr.Lightness=L;
    HlsClr.Saturation=S;
    return HlsClr;
}

Color ramps

• By accessing the individual colors in a ramp
• By using the ramp object directly as a property or in a method of another object

1. To retrieve individual colors from a color ramp, set the Size property according to the number of Color objects you want to retrieve from the ramp.
2. Call the CreateRamp method, which populates the Color and the Colors properties. The Color property holds a read-only, zero-based array of Color objects, returned by index.

Dim colorRamp As IRandomColorRamp=New RandomColorRampClass()
colorRamp.Size=10
Dim bOK As Boolean
colorRamp.CreateRamp( bOK)
If (bOK) Then
    ' Access the Color array here, for example, set colors
    ' for an array of symbols, or map layers, and so on.
    For i As Integer=0 To colorRamp.Size - 1 Step i + 1
    Next
End If

IRandomColorRamp colorRamp=new RandomColorRampClass();
colorRamp.Size=10;
bool bOK;
colorRamp.CreateRamp(out bOK);
if ((bOK))
{
    // Access the Color array here, for example, set colors
    // for an array of symbols, or map layers, and so on.
    for (int i=0; i <= colorRamp.Size - 1; i++){}
}

Dim algoRamp As IAlgorithmicColorRamp=New AlgorithmicColorRampClass()
algoRamp.FromColor=myFromColorObject
algoRamp.ToColor=myToColorObject
Dim gradFill As IGradientFillSymbol=New GradientFillSymbolClass()
gradFill.ColorRamp=TryCast(algoRamp, IGradientFillSymbol)
gradFill.IntervalCount=5

IAlgorithmicColorRamp algoRamp=new AlgorithmicColorRampClass();
algoRamp.FromColor=myFromColorObject;
algoRamp.ToColor=myToColorObject;
IGradientFillSymbol gradFill=new GradientFillSymbolClass();
gradFill.ColorRamp=(IGradientFillSymbol)algoRamp;
gradFill.IntervalCount=5;

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