/* make a displayable power spectrum for an image
 *
 * Author: Nicos Dessipris
 * Written on: 27/03/1991
 * Modified on :
 * 16/6/93 J.Cupitt
 *	- im_ioflag() changed to im_iocheck()
 * 23/2/95 JC
 *	- rewritten for partials
 * 10/9/98 JC
 *	- frees memory more quickly
 * 2/4/02 JC
 *	- any number of bands
 * 7/2/10
 * 	- gtkdoc
 * 	- cleanups
 * 3/1/14
 * 	- redone as a class
 */

/*

	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

 */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif /*HAVE_CONFIG_H*/
#include <glib/gi18n-lib.h>

#include <stdio.h>
#include <stdlib.h>

#include <vips/vips.h>
#include "pfreqfilt.h"

typedef VipsFreqfilt VipsSpectrum;
typedef VipsFreqfiltClass VipsSpectrumClass;

G_DEFINE_TYPE(VipsSpectrum, vips_spectrum, VIPS_TYPE_FREQFILT);

static int
vips_spectrum_build(VipsObject *object)
{
	VipsFreqfilt *freqfilt = VIPS_FREQFILT(object);
	VipsImage **t = (VipsImage **) vips_object_local_array(object, 5);

	VipsImage *in;

	if (VIPS_OBJECT_CLASS(vips_spectrum_parent_class)->build(object))
		return -1;

	in = freqfilt->in;

	if (in->BandFmt != VIPS_FORMAT_COMPLEX) {
		if (vips_fwfft(in, &t[0], NULL))
			return -1;
		in = t[0];
	}

	if (vips_abs(in, &t[1], NULL) ||
		vips_scale(t[1], &t[2], "log", TRUE, NULL) ||
		vips_wrap(t[2], &t[3], NULL))
		return -1;

	if (vips_image_write(t[3], freqfilt->out))
		return -1;

	return 0;
}

static void
vips_spectrum_class_init(VipsSpectrumClass *class)
{
	VipsObjectClass *vobject_class = VIPS_OBJECT_CLASS(class);

	vobject_class->nickname = "spectrum";
	vobject_class->description = _("make displayable power spectrum");
	vobject_class->build = vips_spectrum_build;
}

static void
vips_spectrum_init(VipsSpectrum *spectrum)
{
}

/**
 * vips_spectrum: (method)
 * @in: input image
 * @out: (out): output image
 * @...: %NULL-terminated list of optional named arguments
 *
 * Make a displayable (ie. 8-bit unsigned int) power spectrum.
 *
 * If @in is non-complex, it is transformed to Fourier space. Then the
 * absolute value is passed through vips_scale() in log mode, and vips_wrap().
 *
 * See also: vips_fwfft(), vips_scale(), vips_wrap().
 *
 * Returns: 0 on success, -1 on error.
 */
int
vips_spectrum(VipsImage *in, VipsImage **out, ...)
{
	va_list ap;
	int result;

	va_start(ap, out);
	result = vips_call_split("spectrum", ap, in, out);
	va_end(ap);

	return result;
}
