#include "ltwrappr.h"

static L_INT LBitmap::FrqFilter(pFTArray, prcRange, uFlags)


pointer to structure

LPRECT prcRange;

pointer to range rectangle

L_UINT uFlags;


Filters the frequency harmonics data produced by a Fourier Transform function using a range rectangle.

Parameter Description
pFTArray Pointer to an FTARRAY structure. The acxData member of the FTARRAY structure is a two-dimensional array holding the frequency components.
prcRange Specifies the filter dimension that will be applied, it represents the frequency range to be kept or removed. The left value refers to the minimum X harmonic, the right refers to the maximum X harmonic, the top refers to the minimum Y harmonic and the bottom refers to the maximum Y harmonic. The maximum X harmonic equals Width 1 and the maximum Y harmonic equals Height 1.
uFlags Flags that indicate the operation to be performed on the specified X and Y harmonics ranges. You can use a bit wise OR (|) to specify one flag from each group.
  The following flags represent operations on the X harmonics range:
  Value Meaning
  FRQ_INSIDE_X [0x0001] Keep the X harmonics inside X range and remove outside ones.
  FRQ_OUTSIDE_X [0x0002] Remove the X harmonics inside X range and keep outside ones.
  The following flags represent operations on the Y harmonics range:
  Value Meaning
  FRQ_INSIDE_Y [0x0010] Keep the Y harmonics inside Y range and remove outside ones.
  FRQ_OUTSIDE_Y [0x0020] Remove the Y harmonics inside Y range and keep outside ones.



The function was successful.

< 1

An error occurred. Refer to Return Codes.


This function is used only when working with Fourier Transform functions.

Before using this function, call the LBitmap::AllocFTArray function to allocate a FTARRAY structure large enough to hold the Fourier Transform coefficients for pBitmap. When the array is no longer needed, free the allocated array by calling the LBitmap::FreeFTArray function.

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

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.

Required DLLs and Libraries


For a listing of the exact DLLs and Libraries needed, based on the toolkit version, refer to Files To Be Included With Your Application.


Win32, x64.

See Also


LBitmap::Fragment, LBitmap::HighPassFilter, LBitmap::UnsharpMask, LBitmap::AverageFilter, LBitmap::MedianFilter, LBitmap::AddNoise, LBitmap::IntensityDetect, LBitmap::SpatialFilter, LBitmap::BinaryFilter, LBitmap::MaxFilter, LBitmap::MinFilter, LBitmap::AddShadow LBitmap::AllocFTArray, LBitmap::ChangeHueSatInt, LBitmap::ColorReplace, LBitmap::ColorThreshold, LBitmap::DFT, LBitmap::DirectionEdgeStatistical, LBitmap::FFT, LBitmap::FreeFTArray, LBitmap::FrqFilterMask, LBitmap::FTDisplay, LBitmap::GetStatisticsInfo, LBitmap::GetFeretsDiameter, LBitmap::GetObjectInfo, LBitmap::GetRgnContourPoints, LBitmap::GetRgnPerimeterLength, LBitmap::MathFunction, LBitmap::RevEffect, LBitmap::Segment, LBitmap::SubtractBackground, LBitmap::UserFilter, LBitmap::DirectionEdgeStatistical2


Raster Image Functions: Fourier Transform Functions


Removing Noise


Raster Image Functions: Removing Noise


L_INT LBitmap__FrqFilterExample(LBitmap *pLeadBitmap, pFTARRAY pFTArray) 
   /* this example  filters the acxData of a pFTARRAY structure produced by the Fast Fourier Transform function*/ 
   RECT    rcRange; 
   rcRange.left  = 0; 
   rcRange.right = pLeadBitmap->GetWidth () / 4; = 0; 
   rcRange.bottom = pLeadBitmap->GetHeight () / 2; 
   /*lpFTData is  known*/ 
   /* filters the frequencies*/ 
   return LBitmap::FrqFilter(pFTArray, &rcRange, FRQ_INSIDE_X | FRQ_INSIDE_Y); 

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