LBitmap::EdgeDetector

#include "ltwrappr.h"

virtual L_INT LBitmap::EdgeDetector (uThreshold, uFilter)

L_UINT uThreshold;	/* threshold value */
L_UINT uFilter;	/* filter to be used */

Applies the specified edge filter to the class object's bitmap. This function is available in the Document Toolkits.

Parameter	Description
uThreshold	Threshold value used to determine which pixels are edge pixels. If the difference determined for a pixel is greater than this value, the pixel is an edge pixel.
uFilter	Flag that indicates which edge detection filter to apply. Possible values are:

	Value	Meaning
	EDG_SOBEL_VERT	[0x0101] Detect the vertical edges
	EDG_SOBEL_HORZ	[0x0102] Detect the horizontal edges
	EDG_SOBEL_ALL	[0x0103] Detect horizontal & vertical edges
	EDG_PREWITT_VERT	[0x0201] Detect the vertical edges
	EDG_PREWITT_HORZ	[0x0202] Detect the horizontal edges
	EDG_PREWITT_ALL	[0x0203] Detect horizontal & vertical edges
	EDG_LAPLACE_1	[0x0301] Detect vertical & horizontal edges
	EDG_LAPLACE_2	[0x0302] Detect general edges
	EDG_LAPLACE_3	[0x0303] Detect general edges. (The filter used for this option is different than the filter used for the EDG_LAPLACE_2 filter.)
	EDG_LAPLACE_DIAG	[0x0304] Detect the diagonal edges
	EDG_LAPLACE_HORZ	[0x0305] Detect the horizontal edges
	EDG_LAPLACE_VERT	[0x0306] Detect the vertical edges
	EDG_GRADIENT_N	[0x0401] Detect north edges
	EDG_GRADIENT_NE	[0x0402] Detect north east edges
	EDG_GRADIENT_E	[0x0403] Detect east edges
	EDG_GRADIENT_SE	[0x0404] Detect south east edges
	EDG_GRADIENT_S	[0x0405] Detect south edges
	EDG_GRADIENT_SW	[0x0406] Detect south west edges
	EDG_GRADIENT_W	[0x0407] Detect west edges
	EDG_GRADIENT_NW	[0x0408] Detect north west edges

Returns

SUCCESS	The function was successful.
< 1	An error occurred. Refer to Return Codes.

Comments

Filters such as Sobel filter, Prewitt filter, Laplacian filter, and Gradient filter are used to determine the pixels belonging to edges in the bitmap.

This function can process the whole image or a region of the image.

This function supports 12 and 16-bit grayscale and 48 and 64-bit color images. Support for 12 and 16-bit grayscale and 48 and 64-bit color images is available only in the Document/Medical toolkits.

The threshold range for the 16, 48, and 64-bit bitmaps is from 0 to 65535 and for 12-bit bitmaps from 0 to 4095. Otherwise, it is from 0 to 255. The threshold is applied on channels separately.

This function does not support signed data images. It returns the error code ERROR_SIGNED_DATA_NOT_SUPPORTED if a signed data image is passed to this function.

Required DLLs and Libraries

LTDIS
LTFIL
LTIMG

For a listing of the exact DLLs and Libraries needed, based on the toolkit version, refer to Files To Be Included With Your Application.

Functions:	LBitmap::DiffuseGlow, LBitmap::HighPassFilter, LBitmap::MaskConvolution, LBitmap::IntensityDetect, LBitmap::Sharpen, LBitmap::SpatialFilter, Class Members
Topics:	Detecting and Enhancing Edges and Lines
	Raster Image Functions: Image Processing: Filtering Images
	Raster Image Functions: Detecting and Enhancing Edges and Lines