| MF_filter
| MD_filter |
ME_filter |
| MCF_filter |
MCD_filter |
MCE_filter |
| MFb_filter
| MDb_filter |
MEb_filter |
| MCFb_filter |
MCDb_filter |
MCEb_filter |
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| Function | Spatial frequency filtering |
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| Syntax C/C++ | #include <MFstd.h>
void MF_filter( fMatrix Y, fMatrix X, fMatrix Flt, ui ht, ui len );
void MFb_filter( fMatrix Y, fMatrix X, fMatrix Flt, ui ht, ui len, fVector Buf ); |
| C++ MatObj | #include <OptiVec.h>
void matrix<T>::filter( const matrix<T>& MX, const matrix<T>& MFlt );
void matrix<T>::b_filter( const matrix<T>& MX, const matrix<T>& MFlt, vector<T>& Buf ); |
| Pascal/Delphi | uses MFstd;
procedure MF_filter( MY, MX, MFlt:fMatrix; ht, len:UIntSize );
procedure MFb_filter( MY, MX, MFlt:fMatrix; ht, len:UIntSize; Buf:fVector ); |
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| CUDA function C/C++ | #include <cudaMFstd.h>
int cudaMF_filter( fMatrix d_MY, fMatrix d_MX, fMatrix d_MFlt, ui ht, ui len );
void MFcu_filter( fMatrix h_MY, fMatrix h_MX, fMatrix h_MFlt, ui ht, ui len );
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| CUDA function Pascal/Delphi | uses MFstd;
function cudaMF_filter( d_MY, d_MX, d_MFlt:fMatrix; ht, len:UIntSize ): IntBool;
procedure MFcu_filter( h_MY, h_MX, h_MFlt:fMatrix; ht, len:UIntSize );
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| Description | A spatial frequency filter MFlt is applied to the matrix MX. Internally, this is done by performing a Fourier transform on MX, multiplying the transform with MFlt and transforming the product back into the space domain.
Complex versions: MX, MY and the filter MFlt are complex matrices.
Real versions: MX and MY are real. MFlt has to be in the packed complex format that is obtained by Fourier transforming a real matrix with MF_FFT (see that function for the description of the packed complex format) or by using MF_convolve.
If MX is non-periodic, the edges of the filtered function may be spoiled by wrap-around. See VF_convolve about how to avoid end-effects. As described there for vectors, embed the matrix MX in a larger matrix or remove a possible linear trends in both dimensions.
Internally, MF_filter allocates and frees additional workspace memory. For repeated calls, this would be inefficient. In such a case, it is recommended to use MFb_filter instead. The size of Buf must be:
| C/C++, real: | sizeof(Buf) >= ht*(len+4) |
| C/C++, complex: | sizeof(Buf) >= ht*len |
| Pascal/Delphi, real or complex: | sizeof(Buf) >= ht*len |
Additionally, Buf must be 128-bit (P8) or 256-bit (P9) aligned. This usually means you can only take a vector allocated by the VF_vector family as Buf.
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| Error handling | If either ht or len is not a power of 2, VF_FFT (on which MF_filter is based) complains "Size must be an integer power of 2" and the program is aborted. |
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