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/* creates an ideal filter.
*
* 02/01/14
* - from ideal.c
*/
/*
This file is part of VIPS.
VIPS is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301 USA
*/
/*
These files are distributed with VIPS - http://www.vips.ecs.soton.ac.uk
*/
/*
#define VIPS_DEBUG
*/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif /*HAVE_CONFIG_H*/
#include <glib/gi18n-lib.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <math.h>
#include <vips/vips.h>
#include "pcreate.h"
#include "point.h"
#include "pmask.h"
G_DEFINE_TYPE( VipsMaskIdeal, vips_mask_ideal, VIPS_TYPE_MASK );
static double
vips_mask_ideal_point( VipsMask *mask, double dx, double dy )
{
VipsMaskIdeal *ideal = (VipsMaskIdeal *) mask;
double fc = ideal->frequency_cutoff;
double dist2 = dx * dx + dy * dy;
double fc2 = fc * fc;
return( dist2 <= fc2 ? 0.0 : 1.0 );
}
static void
vips_mask_ideal_class_init( VipsMaskIdealClass *class )
{
GObjectClass *gobject_class = G_OBJECT_CLASS( class );
VipsObjectClass *vobject_class = VIPS_OBJECT_CLASS( class );
VipsMaskClass *mask_class = VIPS_MASK_CLASS( class );
gobject_class->set_property = vips_object_set_property;
gobject_class->get_property = vips_object_get_property;
vobject_class->nickname = "mask_ideal";
vobject_class->description = _( "make an ideal filter" );
mask_class->point = vips_mask_ideal_point;
VIPS_ARG_DOUBLE( class, "frequency_cutoff", 6,
_( "Frequency cutoff" ),
_( "Frequency cutoff" ),
VIPS_ARGUMENT_REQUIRED_INPUT,
G_STRUCT_OFFSET( VipsMaskIdeal, frequency_cutoff ),
0.0, 1000000.0, 0.5 );
}
static void
vips_mask_ideal_init( VipsMaskIdeal *ideal )
{
ideal->frequency_cutoff = 0.5;
}
/**
* vips_mask_ideal:
* @out: (out): output image
* @width: image size
* @height: image size
* @frequency_cutoff: threshold at which filter ends
* @...: %NULL-terminated list of optional named arguments
*
* Optional arguments:
*
* * @nodc: don't set the DC pixel
* * @reject: invert the filter sense
* * @optical: coordinates in optical space
* * @uchar: output a uchar image
*
* Make an ideal high- or low-pass filter, that is, one with a sharp cutoff
* positioned at @frequency_cutoff, where @frequency_cutoff is in
* the range 0 - 1.
*
* This operation creates a one-band float image of the specified size.
* The image has
* values in the range [0, 1] and is typically used for multiplying against
* frequency domain images to filter them.
* Masks are created with the DC component at (0, 0). The DC pixel always
* has the value 1.0.
*
* Set @nodc to not set the DC pixel.
*
* Set @optical to position the DC component in the centre of the image. This
* makes the mask suitable for multiplying against optical Fourier transforms.
* See vips_wrap().
*
* Set @reject to invert the sense of
* the filter. For example, low-pass becomes low-reject.
*
* Set @uchar to output an 8-bit unsigned char image rather than a
* float image. In this case, pixels are in the range [0 - 255].
*
* See also: vips_mask_ideal(), vips_mask_ideal_ring(),
* vips_mask_ideal_band(), vips_mask_butterworth(),
* vips_mask_butterworth_ring(), vips_mask_butterworth_band(),
* vips_mask_gaussian(), vips_mask_gaussian_ring(),
* vips_mask_gaussian_band().
*
* Returns: 0 on success, -1 on error
*/
int
vips_mask_ideal( VipsImage **out, int width, int height,
double frequency_cutoff, ... )
{
va_list ap;
int result;
va_start( ap, frequency_cutoff );
result = vips_call_split( "mask_ideal", ap, out, width, height,
frequency_cutoff );
va_end( ap );
return( result );
}
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