L_DFTBitmap

#include "l_bitmap.h"

L_LTIMGCOR_API L_INT L_DFTBitmap (pBitmap, pFTArray, prcRange, uFlags)

Computes the Discrete Fourier transform of an image or the Inverse Discrete Fourier transform as specified in the uFlags parameter.

Returns

Comments

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.

This function converts the image from the time domain to the frequency domain and vice versa using the Discrete Fourier Transform algorithm. Use the L_FFTBitmap to use a Fast Fourier Transform algorithm on a bitmap. Please note however, that this function does not impose the size restrictions (the width and height having to be powers of 2) that the Fast Fourier Transform function, L_FFTBitmap, imposes upon bitmaps.

Before using this function, you need to use the L_AllocFTArray function to allocate a FTARRAY structure large enough to hold Fourier Transform coefficients for pBitmap. When you are finished, you should free the allocated array by calling the L_FreeFTArray function.

This function does not work on regions. If a bitmap has a region the function ignores it and processes the entire bitmap.

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

This function does not support 12 and 16-bit grayscale and 48 and 64-bit color images. If the image is 12 and 16-bit grayscale and 48 and 64-bit color, the function will not return an error.

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

Platforms

Windows 2000 / XP/Vista.

See Also

Example

This example loads a bitmap and applies DFT function.

#if defined (LEADTOOLS_V16_OR_LATER)
 L_INT DFTBitmapexample(L_VOID)
{
   L_INT nRet;
   RECT    rcRange;
   BITMAPHANDLE LeadBitmap;   /* Bitmap handle to hold the loaded image. */
   pFTARRAY  pFTArray;

   /* Load the bitmap, keeping the bits per pixel of the file */
   nRet = L_LoadBitmap(TEXT("%UserProfile%\\My Documents\\LEADTOOLS Images\\IMAGE1.CMP"), &LeadBitmap, sizeof(BITMAPHANDLE), 0, ORDER_BGR, NULL, NULL);
   if(nRet !=SUCCESS)
      return nRet;

   /*Allocate FT buffer*/
   nRet = L_AllocFTArray(&LeadBitmap, &pFTArray, sizeof(FTARRAY), 0);
   if(nRet !=SUCCESS)
      return nRet;

   rcRange.left  = 0;
   rcRange.right = LeadBitmap.Width / 4;
   rcRange.top = 0;
   rcRange.bottom = LeadBitmap.Height / 2;

   /* Apply DFT*/
   nRet = L_DFTBitmap(&LeadBitmap, pFTArray, &rcRange, DFT_DFT | DFT_GRAY | DFT_RANGE| DFT_INSIDE_X| DFT_OUTSIDE_Y);
   if(nRet !=SUCCESS)
      return nRet;

   /* Free FT buffer */
   nRet = L_FreeFTArray(pFTArray, 0);
   if(nRet !=SUCCESS)
      return nRet;
   nRet = L_SaveBitmap(TEXT("%UserProfile%\\My Documents\\LEADTOOLS 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;
}
#else
 L_INT DFTBitmapexample(L_VOID)
{
   L_INT nRet;
   RECT    rcRange;
   BITMAPHANDLE LeadBitmap;   /* Bitmap handle to hold the loaded image. */
   pFTARRAY  pFTArray;

   /* Load the bitmap, keeping the bits per pixel of the file */
   nRet = L_LoadBitmap(TEXT("%UserProfile%\\My Documents\\LEADTOOLS Images\\IMAGE1.CMP"), &LeadBitmap, sizeof(BITMAPHANDLE), 0, ORDER_BGR, NULL, NULL);
   if(nRet !=SUCCESS)
      return nRet;

   /*Allocate FT buffer*/
   nRet = L_AllocFTArray(&LeadBitmap, &pFTArray, sizeof(FTARRAY));
   if(nRet !=SUCCESS)
      return nRet;

   rcRange.left  = 0;
   rcRange.right = LeadBitmap.Width / 4;
   rcRange.top = 0;
   rcRange.bottom = LeadBitmap.Height / 2;

   /* Apply DFT*/
   nRet = L_DFTBitmap(&LeadBitmap, pFTArray, &rcRange, DFT_DFT | DFT_GRAY | DFT_RANGE| DFT_INSIDE_X| DFT_OUTSIDE_Y);
   if(nRet !=SUCCESS)
      return nRet;

   /* Free FT buffer */
   nRet = L_FreeFTArray(pFTArray);
   if(nRet !=SUCCESS)
      return nRet;
   nRet = L_SaveBitmap(TEXT("%UserProfile%\\My Documents\\LEADTOOLS 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;
}
#endif // LEADTOOLS_V16_OR_LATER