finterp.c File Reference

Fourier zero-padding interpolation. More...

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include <fftw3.h>
#include "basic.h"
#include "finterp.h"

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Functions
int	FourierScale2d (float *Dest, int DestWidth, float XStart, int DestHeight, float YStart, const float *Src, int SrcWidth, int SrcHeight, int NumChannels, double PsfSigma, boundaryhandling Boundary)
	Scale image with Fourier zero padding. More...

Variables
int(*	ExtensionMethod [3])(int, int)

Detailed Description

Fourier zero-padding interpolation.

Author

Pascal Getreuer getre.nosp@m.uer@.nosp@m.gmail.nosp@m..com

Definition in file finterp.c.

Function Documentation

int FourierScale2d	(	float *	Dest,
		int	DestWidth,
		float	XStart,
		int	DestHeight,
		float	YStart,
		const float *	Src,
		int	SrcWidth,
		int	SrcHeight,
		int	NumChannels,
		double	PsfSigma,
		boundaryhandling	Boundary
	)

Scale image with Fourier zero padding.

Parameters

Dest	pointer to memory for holding the interpolated image
DestWidth	output image width
XStart	leftmost sample location (in input coordinates)
DestHeight	output image height
YStart	uppermost sample location (in input coordinates)
Src	the input image
SrcWidth,SrcHeight,NumChannels	input image dimensions
PsfSigma	Gaussian PSF standard deviation
Boundary	boundary handling

Returns

1 on success, 0 on failure.

The image is first mirror folded with half-sample even symmetry to avoid boundary artifacts, then transformed with a real-to-complex DFT.

The interpolation is computed so that Dest[m + DestWidth*n] is the interpolation of Input at sampling location (XStart + m*SrcWidth/DestWidth, YStart + n*SrcHeight/DestHeight) for m = 0, ..., DestWidth - 1, n = 0, ..., DestHeight - 1, where the pixels of Src are located at the integers.

Definition at line 266 of file finterp.c.

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Variable Documentation

int(* ExtensionMethod[3])(int, int)

Initial value:

=
    {ConstExtension, HSymExtension, WSymExtension}

Definition at line 73 of file finterp.c.