Removes low frequency details in a bitmap, resulting in a sharpened image.


#include "ltwrappr.h"

L_INT LBitmap::HighPassFilter(uRadius, uOpacity, uFlags = 0)


L_UINT uRadius

Value greater than 0 that indicates the radius of the neighborhood on which the filter is applied, in pixels.

L_UINT uOpacity

Value that represents the intensity of the effect. The valid range is from 0 to 100. At 100, only the object outlines remain.

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 filter removes low-frequency detail in the bitmap. The effect is opposite to that of the Gaussian Blur filter (LBitmap::GaussianFilter).

To increase the thickness of the edges, increase the value of uRadius. Usually a low value for uRadius is better.

Unlike the LBitmap::UnsharpMask function, when using this function image noise is not increased.

For an example, click here

If the bitmap has a region, the effect will be applied on the region only.

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.

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

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.

High Pass Function - Before

High Pass Function - Before

High Pass Function - After

High Pass Function - After

View additional platform support for this High Pass function.

Required DLLs and Libraries


Win32, x64.

See Also




L_INT LBitmap__HighPassFilterExample() 
   L_INT nRet; 
   LBitmap LeadBitmap; 
   nRet =LeadBitmap.Load(MAKE_IMAGE_PATH(TEXT("sample5.cmp")), 0,ORDER_BGR); 
   if(nRet !=SUCCESS) 
      return nRet; 
   nRet =LeadBitmap.HighPassFilter(10, 100); 
   if(nRet !=SUCCESS) 
      return nRet; 
   return SUCCESS; 
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