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LBitmap::EdgeDetector

Summary

Applies the specified edge filter to the class object's bitmap.

Syntax

#include "ltwrappr.h"

virtual L_INT LBitmap::EdgeDetector (uThreshold, uFilter, uFlags = 0)

Parameters

L_UINT 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.

L_UINT 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

L_UINT32 uFlags

Reserved for future use. Must be 0.

Returns

Value	Meaning
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 ranges are:

0 to 65535 for the 16, 48, and 64-bit bitmaps.
0 to 4095 for 12-bit bitmaps.
0 to 255 otherwise.

The threshold is applied on channels separately.

This function does not support 32-bit grayscale images. It returns the error code ERROR_GRAY32_UNSUPPORTED if a 32-bit grayscale image is passed to this function.

Edge Detector Function - Before

Edge Detector Function - After

View additional platform support for this Edge Detector function.

Required DLLs and Libraries

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

Platforms

Win32, x64.

Example

L_INT LBitmap__EdgeDetectorExample(LBitmap & Bitmap, L_TCHAR * szFile) 
{ 
   L_INT nRet; 
 
   nRet =Bitmap.Load(szFile); 
   if(nRet !=SUCCESS) 
      return nRet; 
   nRet =Bitmap.EdgeDetector(60, EDG_SOBEL_ALL); 
   if(nRet !=SUCCESS) 
      return nRet; 
 
   return SUCCESS; 
}