#include "l_bitmap.h"

L_LTIMGEFX_API L_INT L_EdgeDetectEffectBitmap(pBitmap, uLevel, nThreshold, uFlags)


pointer to the bitmap handle

L_UINT uLevel;

edge weight

L_INT nThreshold;

threshold value

L_UINT uFlags;

edges type

Performs edge detection on the image.

Parameter Description
pBitmap Pointer to the bitmap handle that references the bitmap on which to apply the effect.
uLevel Level value used to determine the brightness of the edges. Standard value is 50. Range between 1 and 100. Big values will produce bright edges.
nThreshold Threshold value used to determine which pixels are going to be filtered. If the difference determined for a pixel is less than this value, the pixel is set to 0. If the difference is greater, the filter will be applied to the pixel. The valid range is from 0 - 65535 for 64-bit, 48-bit and 16-bit grayscale images and from 0 - 4095 for 12-bit grayscale images. Otherwise, it is from 0 to 255.
uFlags Flag that indicates the type of edge to generate. Possible values are:
  Value Meaning
  EDGE_SOFT [0] Generate softer (smoother) edges.
  EDGE_SOLID [1] Generate rougher edges.



The function was successful.

< 1

An error occurred. Refer to Return Codes.


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.

This function detects the edges in a bitmap and then replaces the values of edges by new values calculated according to the uFlags.

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 in the Document and Medical Imaging toolkits.

To update a status bar or detect a user interrupt during execution of this function, refer to L_SetStatusCallback.

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.

Required DLLs and Libraries


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


Win32, x64, Linux.

See Also


L_EdgeDetectorBitmap, L_SpatialFilterBitmap, L_EdgeDetectStatisticalBitmap, L_DirectionEdgeStatisticalBitmap, L_BricksTextureBitmap, L_DeskewBitmap, L_DiffuseGlowBitmap, L_GlowFilterBitmap, L_HalfTonePatternBitmap, L_PerspectiveBitmap, L_PlasmaFilterBitmap, L_PointillistBitmap, L_DiffuseGlowBitmap, L_HighPassFilterBitmap, L_MaskConvolutionBitmap


Raster Image Functions: Modifying Intensity Values


Detecting and Enhancing Edges and Lines


Raster Image Functions: Detecting and Enhancing Edges and Lines


L_INT EdgeDetectEffectBitmapExample(L_VOID) 
   L_INT nRet; 
   BITMAPHANDLE LeadBitmap;   /* Bitmap handle for the image */ 
   /* Load a bitmap at its own bits per pixel  */ 
   nRet = L_LoadBitmap (MAKE_IMAGE_PATH(TEXT("sample5.cmp")), &LeadBitmap, sizeof(BITMAPHANDLE), 0, ORDER_BGR, NULL, NULL);  
   if(nRet !=SUCCESS) 
      return nRet; 
   /* Apply find edges effect on the image*/ 
   nRet = L_EdgeDetectEffectBitmap(&LeadBitmap, 50, 0, EDGE_SOFT); 
   if(nRet !=SUCCESS) 
      return nRet; 
   nRet = L_SaveBitmap(MAKE_IMAGE_PATH(TEXT("Result.BMP")), &LeadBitmap, FILE_BMP, 24, 0, NULL); 
   if(nRet !=SUCCESS) 
      return nRet; 
   //free bitmap  
   return SUCCESS; 
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