This method adjusts the chrominance of a raster image.
Parameters
| Name | Explanation |
|---|---|
| Points | An array of x and y coordinate values defining
points of a polygonal area on the image. (in pixels) In C++Builder, the size of the Points array is given by Points_Size - 1 |
| Level | Chrominance Level (-100 to 1000) |
Return Value
Returns True if successful, otherwise returns False.
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 vikEffectMask. Set the mask image handle in the MaskImageHandle property
- To process the total image, set the SelectMode property to vikEffectAll.
- To process the polygonal area on the image, set the SelectMode property to vikEffectPolygon. Select the polygon by setting the appropriate coordinate values for the points of the polygon in the Points array. 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 vikEffectEllipse. 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 vikEffectPolygon or vikEffectEllipse, the InOut property should be set. When the SelectMode property is set to values other than vikEffectPolygon, please set the Points parameter to a dummy array or to NULL.
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.
[Differences with ImageKit 7/8/9/10 ActiveX]
-Parameters x and y have been changed to TPoint type.
-When used in Delphi, it is no longer necessary to pass the number
of array elements that specify x and y as an argument.