L_UserFilterBitmap

#include "l_bitmap.h"

L_INT EXT_FUNCTION L_UserFilterBitmap (pBitmap, pFilter);

pBITMAPHANDLE pBitmap;	/* pointer to the bitmap handle */
LPUSERFLT pFilter;	/* pointer to a structure */

Filters the bitmap based on a user-defined filter / mask. This function is similar to the spatial and binary filter functions. This function is available in the Raster Pro and above toolkits.

Parameter	Description
pBitmap	Pointer to the bitmap handle that references the bitmap on which to apply the effect.
pFilter	Pointer to an USERFLT structure that contains information about the mask to be applied.

Returns

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

Comments

With this function you can create a user-defined filter and apply it to the image. The selected filter is passed as a parameter to this function. The filter has a rectangular form (matrix) where the values are user-defined. It allows the creation of simple customized filters, where each value found in matrix is multiplied by the corresponding pixel, and then the specified operation is performed on the results.

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.

When the filter is applied to pixels from the edge and you choose the sum operation, the edge rows and columns are duplicated. For example, if the pixel (-1, 5) is needed, the pixel (0, 5) is used instead.

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.

Required DLLs and Libraries

LTIMG

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 95 / 98 / Me, Windows 2000 / XP, Windows CE.

See Also

Functions:	L_MaxFilterBitmap, L_MinFilterBitmap, L_AddBitmapNoise, L_SharpenBitmap, L_PosterizeBitmap, L_MosaicBitmap, L_EmbossBitmap, L_AverageFilterBitmap, L_MedianFilterBitmap, L_IntensityDetectBitmap, L_SpatialFilterBitmap, L_BinaryFilterBitmap, L_OilifyBitmap, L_SolarizeBitmap, L_WindowLevel, L_AddShadowBitmap, L_AllocFTArray, L_ChangeHueSatIntBitmap, L_ColorReplaceBitmap, L_ColorThresholdBitmap, L_DFTBitmap, L_DirectionEdgeStatisticalBitmap, L_FFTBitmap, L_FreeFTArray, L_FrqFilterBitmap, L_FrqFilterMaskBitmap, L_FTDisplayBitmap, L_GetBitmapStatisticsInfo, L_GetFeretsDiameter, L_GetObjectInfo, L_GetRgnContourPoints, L_GetRgnPerimeterLength, L_MathFunctionBitmap, L_RevEffectBitmap, L_SegmentBitmap, L_SubtractBackgroundBitmap, L_HighPassFilterBitmap
Topics:	Raster Image Functions: Modifying Intensity Values
	Removing Noise

Example

/*In this example the high pass filter will be applied using user defined matrix*/
BITMAPHANDLE  LeadBitmap; /* Bitmap handle for the image */
LPUSERFLT  pFilter;
L_INT  i, j;

/* Load a bitmap at its own bits per pixel  */
L_LoadBitmap (TEXT("IMAGE1.CMP"), &LeadBitmap, sizeof(BITMAPHANDLE), 0, ORDER_BGR, NULL, NULL);
/* Allocate the user filter structure. And also we need a (3x3) matrix with 9 elements. */
pFilter = (LPUSERFLT)malloc(sizeof(USERFLT) + 9 * sizeof(L_INT));
/* Initialize the array with factor used to apply the high pass filter */
for(i = 0; i < 3; i++)
{
   for(j = 0; j < 3; j++)
   {
      if(j == 1 || i == 1)
      {
         if(j == 1 && i == 1)
            pFilter->ufltMatrix[i * 3 + j] = 5;
         else
            pFilter->ufltMatrix[i * 3 + j] = -1;
      }
      else
         pFilter->ufltMatrix[i * 3 + j] = 0;
   }
}
pFilter->uStructSize = sizeof(USERFLT);
pFilter->ufltWidth = 3;
pFilter->ufltHeight = 3;
pFilter->ufltCenter.x = 1;
pFilter->ufltCenter.y = 1;
pFilter->ufltDivisor = 1;
pFilter->nfltOffset = 0;
pFilter->ufltFlag = UD_SUM;

/* Apply the high pass custom filter */
L_UserFilterBitmap (&LeadBitmap, pFilter);

/* Free the filter */
free(pFilter);