OMEGA Pipeline Reference Manual  1.0.5
Functions
Fast Fourier Transformation

Functions

cpl_image * omega_gen_lowpass (int xs, int ys, double sigma_x, double sigma_y)
 Generate a low pass filter for FFT convolution .
cpl_image * omega_get_spatial_freq (cpl_image *flat, cpl_mask *bpm, double gausfilt, int mirrorx, int mirrory)
 Get low spatial frequency componenets from the flat field using the FFTW.
cpl_image * omega_mirror_edges (cpl_image *image, int dx, int dy)
 expand image by mirroring edges

Detailed Description

This module provides functions to do fast fourier transformations

Synopsis:
Functions to deal with fast fourier transformations
#include "omega_bpm.h"
#include "omega_utils.h"

Function Documentation

cpl_image* omega_gen_lowpass ( int  xs,
int  ys,
double  sigma_x,
double  sigma_y 
)

Generate a low pass filter for FFT convolution .

Parameters:
xsx size of the generated image.
ysy size of the generated image.
sigma_xSigma for the gaussian distribution.
sigma_ySigma for the gaussian distribution.
Returns:
1 newly allocated image.

This function generates an image of a 2d gaussian, modified in such a way that the different quadrants have a quadrants of the gaussian in the corner. This image is suitable for FFT convolution. Copied from eclipse, src/iproc/generate.c

The returned image must be deallocated.

Definition at line 84 of file omega_fftw.c.

Referenced by omega_get_spatial_freq().

cpl_image* omega_get_spatial_freq ( cpl_image *  flat,
cpl_mask *  bpm,
double  gausfilt,
int  mirrorx,
int  mirrory 
)

Get low spatial frequency componenets from the flat field using the FFTW.

   Function to calculate the low spatial frequency
Parameters:
flattwilight or dome flat
bpmoptonal bad pixels image
gausfiltGaussian Fourier filter size
mirrorxfor mirroring edges (ocfft continuity)
mirroryfor mirroring edges (ocfft continuity)
medfiltfor cleaning bad pixels
Returns:
1 newly allocated image.

Definition at line 171 of file omega_fftw.c.

References omega_gen_lowpass(), and omega_mirror_edges().

Referenced by omega_make_mflat().

cpl_image * omega_mirror_edges ( cpl_image *  image,
int  dx,
int  dy 
)

expand image by mirroring edges

Parameters:
image_inImage.
x_sizethe number of pixels in x to expand
y_sizethe number of pixels in y to expand

Definition at line 266 of file omega_fftw.c.

Referenced by omega_get_spatial_freq().