Performs a contour segment filter on the source bitmap.


#include "ltwrappr.h"

virtual L_INT LBitmap::ContourFilter (nThreshold, nDeltaDirection, nMaximumError, nOption, uFlags = 0)


L_INT16 nThreshold

Threshold of the gradient magnitude. Values below this will be considered as background, and will be set to 0. Values can be from 1 to 254. A lower threshold provides a better quality image. Default is 15.

L_INT16 nDeltaDirection

Maximum angle for the thinning algorithm. Values can be from 1 to 64. Default is 35.

L_INT16 nMaximumError

Maximum error for approximation algorithm. Values can be from 0 to 255. Default is 5. This parameter is only valid if nOption is CONTOUR_APPROX_COLOR.

L_INT nOption

Flag that controls the resulting image. This value tells the method what process to complete before returning. Possible values are:

Value Meaning
CONTOUR_THIN [0] return after the thinning algorithm
CONTOUR_LINK_BLACKWHITE [1] return after contour linking, using only black and white
CONTOUR_LINK_GRAY [2] return after contour linking, using 256 grayscale
CONTOUR_LINK_COLOR [3] return after contour linking, using colors
CONTOUR_APPROX_COLOR [4] return after line segment approximation, using colors

L_UINT32 uFlags

Reserved for future use. Must be 0.


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


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.

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


Win32, x64.

See Also



L_INT LBitmap__ContourFilterExample() 
   L_INT nRet; 
   LBitmap m_Bitmap; 
   nRet =m_Bitmap.Load(MAKE_IMAGE_PATH(TEXT("image1.cmp")), 0,ORDER_BGR); 
   if(nRet !=SUCCESS) 
      return nRet; 
   // Increase the Saturation 
   nRet =m_Bitmap.ContourFilter(5, 5, 5, CONTOUR_LINK_COLOR); 
   if(nRet !=SUCCESS) 
      return nRet; 
   return SUCCESS; 

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