/* 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;

}