L_HighPassFilterBitmap

#include "l_bitmap.h"

L_LTIMGEFX_API L_INT L_HighPassFilterBitmap(pBitmap, uRadius, uOpacity)

pBITMAPHANDLE pBitmap;	/* pointer to the bitmap handle */
L_UINT uRadius;	/* radius of the neighborhood */
L_UINT uOpacity;	/* opacity */

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

Parameter	Description
pBitmap	Pointer to the bitmap handle that references the bitmap to which to apply the filter.
uRadius	Value greater than 0 that indicates the radius of the neighborhood on which the filter is applied, in pixels.
uOpacity	Value that represents the intensity of the effect. The valid range is from 0 to 100. At 100, only the object outlines remain.

Returns

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

Comments

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

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

Unlike the L_UnsharpMaskBitmap 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 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

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

Windows 2000 / XP/Vista.

See Also

Functions:	L_SharpenBitmap, L_PosterizeBitmap, L_MosaicBitmap, L_EmbossBitmap, L_MedianFilterBitmap, L_AddBitmapNoise, L_IntensityDetectBitmap, L_SpatialFilterBitmap, L_BinaryFilterBitmap, L_SolarizeBitmap, L_WindowLevel, L_UnsharpMaskBitmap, L_GaussianFilterBitmap
Topics:	Raster Image Functions: Filtering Images
	Removing Noise
	Detecting and Enhancing Edges and Lines
	Raster Image Functions: Detecting and Enhancing Edges and Lines

Example

 L_INT HighPassFilterBitmapExample(L_VOID)
{
   L_INT nRet;
   BITMAPHANDLE LeadBitmap;   /* Bitmap handle for the image */

   /* Load a bitmap at its own bits per pixel  */
   nRet = L_LoadBitmap (TEXT("C:\\Program Files\\LEAD Technologies\\LEADTOOLS 15\\Images\\IMAGE3.CMP"), &LeadBitmap, sizeof(BITMAPHANDLE), 0, ORDER_BGR, NULL, NULL);
   if(nRet !=SUCCESS)
      return nRet;

   /*Sharpen image by applying the high pass filter*/
   nRet = L_HighPassFilterBitmap(&LeadBitmap, 10, 100);
   if(nRet !=SUCCESS)
      return nRet;
   nRet = L_SaveBitmap(TEXT("C:\\Program Files\\LEAD Technologies\\LEADTOOLS 15\\Images\\Result.BMP"), &LeadBitmap, FILE_BMP, 24, 0, NULL);
   if(nRet !=SUCCESS)
      return nRet;
   //free bitmap 
   if(LeadBitmap.Flags.Allocated)  
      L_FreeBitmap(&LeadBitmap);  
   return SUCCESS;
}