Chroma (ImageKit Control/ Effect Method)

This method adjusts the chrominance of a raster image.

[Visual Basic] [ Boolean = ]imagekitcontrolname.Effect.Chroma(x As Long, y As Long, Points As Long, Level As Long)

[Visual C++] [ BOOL = ]imagekitcontrolname.GetEffect().Chroma(long *x, long *y, long Points, long Level)

[VB.NET] [ Boolean = ]imagekitcontrolname.Effect.Chroma(ByRef x As Integer, ByRef y As Integer, Points As Integer, Level As Integer)

[C#.NET] [ bool = ]imagekitcontrolname.Effect.Chroma(ref int x, ref int y, int Points, int Level)

Parameters

Name	Explanation
x	An array of x coordinate values defining points of a polygonal area on the image. (in pixels) * (see Note below)
y	An array of y coordinate values defining points of a polygonal area on the image. (in pixels) * (see Note below)
Points	The number of points defining the polygonal area on the image.
Level	Chrominance Level (-100 to 1000)
* NOTE for retrieving array values: In Visual Basic, if the array is defined as Dim x(0 To 2) As Long, then the arguments are returned in x(0). In Visual C++, pass the pointer to the first element in the array. In VB.NET, the arguments are returned in x(0). In C#.NET, the arguments are returned in x[0].

Return Value

Returns True (nonzero) if successful, otherwise returns False (0).

Explanation

The Chroma method adjusts the chrominance of the image. Chrominance refers to the color element of the image whereas Luminance refers to the brightness element. You can adjust the chrominance by using the Level parameter which can have a value ranging from -100 to 1000. When the Level parameter is 0, there is no change in the image color. As the level becomes negative, the colors in the image become less vivid. When the Level parameter reaches -100 the chrominance element is negated leaving only the Luminance element. This is grayscale. Conversely, as the Level parmeter increases from 0, the colors become more vivid.

To execute the Chroma method, set the image handle of the image in the ImageHandle property or the Layer(LayerNo).ImageHandle property. The Chroma method supports 1, 4, 8, 16, 24, and 32 bit images.

Before executing the Chroma method, you must set the area on the image that will be affected. There are 4 ways to do this.

To use a mask image, set the SelectMode property to 0. Set the mask image handle in the MaskImageHandle property
To process the total image, set the SelectMode property to 1
To process the polygonal area on the image, set the SelectMode property to 2. Select the polygon by setting the appropriate coordinate values for the points of the polygon in two arrays, one array for the x coordinate values and one array for the y coordinate values. The pass these arrays to the x and y arguments of the Chroma method. The number of points defining the polygon must be 3 or more
To process an elliptical area on the image, set the SelectMode property to 3. Select the ellipse by setting the appropriate values for the bounding rectangle in the RectLeft, RectTop, RectRight, and RectBottom properties

When the SelectMode property is set to values other than 2 (ikEffectPolygon), please set dummy arrays in the x and y parameters and set the Points parameter to 0.
When the SelectMode property is set to 2 or 3, the appropriate value must be set in the InOut property. When a 1, 4, or 8 bit image is processed, the SelectMode property must be set to process the total image (i.e. SelectMode= 1). If successful the resulting raster image data is set in the LayerNo property (the ImageHandle property or the Layer(LayerNo).ImageHandle property. If unsuccessful, 0 is returned.

When the Caption, Message, and ButtonName properties are blank, the progress dialog box will not be displayed. When the progress dialog box is displayed, the percentage that the processing has completed will be shown in the dialog box.

For scripting languages and other programs that require variant types or when using 64 bit builds in VB.NET or C#, please refer to the ChromaVariant method.