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L_SRADAnisotropicDiffusion

Summary

Applies a 2-Dimensional Anisotropic Diffusion filter on an image in order to reduce noise and speckling, while preserving the edges.

Syntax

#include "l_bitmap.h"

L_LTIMGCOR_API L_INT L_SRADAnisotropicDiffusion(pBitmap, nIter, nLambda, pRect)

Parameters

pBITMAPHANDLE pBitmap

Pointer to the bitmap handle.

L_INT nIter

Number of iterations the filter will perform. The default value is 10.

L_INT nLambda

The smoothing time step value. Valid values range from 0 to 100. A value of 0 means nothing will be done to the image. The default value is 50.

LPRECT pRect

Pointer to a rectangle representing the homogeneous region of uniform speckles.

Returns

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

Comments

The Speckle Reducing Anisotropic Diffusion (SRAD) function is similar to the L_AverageFilterBitmap function, but is used to reduce noise and speckling in images while preserving the edges instead of blurring.

LEADTOOLS offers three functions that implement anisotropic diffusion:

L_AnisotropicDiffusionBitmap: L_AnisotropicDiffusion is a slower but more accurate version of L_SRADAnisotropDiffusion.
L_SRADAnisotropicDiffusion: In comparison with conventional anisotropic diffusion, the L_SRADAnisotropicDiffusion uniform areas exhibit more smoothing and edges and features are preserved better.
L_TADAnisotropicDiffusion: L_TADAnisotropicDiffusion employs an edge-seeking diffusion coefficient.

All three reduce noise and preserve edges and perform better than the L_MedianFilterBitmap or L_GaussianFilterBitmap functions. With the anisotropic functions, areas within regions are smoothed, but the edges are not affected.

The number of iterations controls the number of times the filter will be applied to an image. The lower the number of iterations, the faster the filter will perform. Higher iterations typically mean clearer results.

This function can only process the entire image. It does not support regions.

This function supports 8- and 16-bit grayscale images and 24- and 32-bit colored images.

This function supports signed/unsigned images.

Required DLLs and Libraries

LTIMGCOR
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

Win32, x64.

Example

This example loads a bitmap and applies SRADAnisotropicDiffusion.

L_INT SRADAnisotropicDiffusionExample(L_VOID) 
{ 
   L_INT nRet; 
   BITMAPHANDLE LeadBitmap;   /* Bitmap handle to hold the loaded image. */ 
 
   /* Load the bitmap, keeping the bits per pixel of the file */ 
   nRet = L_LoadBitmap(MAKE_IMAGE_PATH(TEXT("DICOM\\IMAGE3.dcm")), &LeadBitmap, sizeof(BITMAPHANDLE), 0, ORDER_BGR, NULL, NULL); 
   if (nRet != SUCCESS) 
      return nRet; 
 
   /* Apply SRADAnisotropicDiffusion filter */ 
   RECT rc; 
   rc.left = 150; 
   rc.right = 180; 
   rc.top = 300; 
   rc.bottom = 330; 
   nRet = L_SRADAnisotropicDiffusion(&LeadBitmap, 10, 50, &rc); 
 
   if (nRet == SUCCESS) 
      nRet = L_SaveBitmap(MAKE_IMAGE_PATH(TEXT("Result.BMP")), &LeadBitmap, FILE_BMP, 24, 0, NULL); 
 
   //free bitmap 
   if (LeadBitmap.Flags.Allocated) 
      L_FreeBitmap(&LeadBitmap); 
 
   return nRet; 
}