This method produces an outline effect on the image.
Public Function Outline(plane As Integer, mode As Integer, level As Integer) As Boolean
public bool Outline(int plane, int mode, int level);
Parameters
plane
Sets which plane will be used to
process the outline (0:Y, 1:R, 2:G, 3:B)
mode
Sets the edge filtering function used
to process the outline (0:Differential, 1:Roberts, 2:Sobel)
level
Sets the brightness at which an
outline is drawn (from 0 to 100)
Return Value
Returns True if successful. Returns False if unsuccessful.
Explanation
The Outline method produces an outline of a raster image by identifying and displaying only the "edges" within the image. In general, the luminance plane is most commonly used. (Plane parameter = 0). In this case, differences in brightness are used to identify edges. However, the red plane, green plane or blue plane can also be used to identify an edge So, for example, if the red plane is used (Plane parameter = 1) then differences in the R values would be used to identify the edges within an image.
The Mode parameter determines how an edge is identified. The Level parameter determines at which value an edge will be displayed. When the Differential Operator is used, the differences between the pixel values (either brightness, red, green, or blue) are calculated and then depending on the value of the Level parameter, the edges are displayed. The Differential Operator evaluates these difference in a horizontal and/or vertical direction. The Roberts Operator also uses a differential calculation, but evaluates these differences at a 45 degree orientation. The Sorbel Operator is very similar to the above two operators except that with Sorbel there is an additional correction for images that have a lot of complexity.
To execute the Outline method, set the image handle of the image in the SourceImage property. The Outline method supports 8 bit grayscale, 16, 24, and 32 bit images.
Before executing the Outline 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 EffectMask. Set the mask image handle in the SourceMask property
- To process the total image, set the SelectMode property to EffectAll
- To process the polygonal area on the image, set the SelectMode property to EffectPolygon. Select the polygon by setting the appropriate coordinate values for the points of the polygon in the Point property
- To process an elliptical area on the image, set the SelectMode property to EffectEllipse. Select the ellipse by setting the appropriate values for the bounding rectangle in the Rect property
When the SelectMode property is set to EffectPolygon or EffectEllipse, the appropriate values must be set in the Inside property.
If successful the resulting raster image data is set in the DestinationImage property.