/* im_scale

 *

 * Author: John Cupitt

 * Written on: 22/4/93

 * Modified on:

 * 30/6/93 JC

 *  - adapted for partial v2

 *  - ANSI

 * 31/8/93 JC

 *  - calculation of offset now includes scale

 * 8/5/06

 *  - set Type on output too

 * 16/10/06

 *  - what? no, don't set Type, useful to be able to scale histograms, for

 *    example

 * 1/2/10

 *  - gtkdoc

 * 30/5/13

 *  - redo as a class

 *  - add log scale and exponent as an option

 * 14/1/14

 *  - use linear uchar mode

 * 14/7/14

 *  - round to nearest on uchar output

 * 29/12/18 kleisauke

 *  - ... and round to nearest in log mode too

 */

/*

  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 <math.h>

#include <vips/vips.h>

#include "pconversion.h"

typedef struct _VipsScale {

  VipsConversion parent_instance;

  VipsImage *in;

  gboolean log;

  double exp;

} VipsScale;

typedef VipsConversionClass VipsScaleClass;

G_DEFINE_TYPE(VipsScale, vips_scale, VIPS_TYPE_CONVERSION);

static int

vips_scale_build(VipsObject *object)

{

  VipsConversion *conversion = VIPS_CONVERSION(object);

  VipsScale *scale = (VipsScale *) object;

  VipsImage **t = (VipsImage **) vips_object_local_array(object, 7);

  double mx;

  double mn;

  if (VIPS_OBJECT_CLASS(vips_scale_parent_class)->build(object))

    return -1;

  if (vips_stats(scale->in, &t[0], NULL))

    return -1;

  mn = *VIPS_MATRIX(t[0], 0, 0);

  mx = *VIPS_MATRIX(t[0], 1, 0);

  if (mn == mx) {

    /* Range of zero: just return black.

     */

    if (vips_black(&t[1], scale->in->Xsize, scale->in->Ysize,

        "bands", scale->in->Bands,

        NULL) ||

      vips_image_write(t[1], conversion->out))

      return -1;

  }

  else if (scale->log) {

    double f = 255.0 / log10(1.0 + pow(mx, scale->exp));

    if (vips_pow_const1(scale->in, &t[2], scale->exp, NULL) ||

      vips_linear1(t[2], &t[3], 1.0, 1.0, NULL) ||

      vips_log10(t[3], &t[4], NULL) ||

      /* Add 0.5 to get round to nearest.

       */

      vips_linear1(t[4], &t[5], f, 0.5,

        "uchar", TRUE,

        NULL) ||

      vips_image_write(t[5], conversion->out))

      return -1;

  }

  else {

    double f = 255.0 / (mx - mn);

    /* Add .5 to get round-to-nearest.

     */

    double a = -(mn * f) + 0.5;

    if (vips_linear1(scale->in, &t[2], f, a,

        "uchar", TRUE,

        NULL) ||

      vips_image_write(t[2], conversion->out))

      return -1;

  }

  return 0;

}

static void

vips_scale_class_init(VipsScaleClass *class)

{

  GObjectClass *gobject_class = G_OBJECT_CLASS(class);

  VipsObjectClass *vobject_class = VIPS_OBJECT_CLASS(class);

  gobject_class->set_property = vips_object_set_property;

  gobject_class->get_property = vips_object_get_property;

  vobject_class->nickname = "scale";

  vobject_class->description = _("scale an image to uchar");

  vobject_class->build = vips_scale_build;

  VIPS_ARG_IMAGE(class, "in", 1,

    _("Input"),

    _("Input image"),

    VIPS_ARGUMENT_REQUIRED_INPUT,

    G_STRUCT_OFFSET(VipsScale, in));

  VIPS_ARG_BOOL(class, "log", 3,

    _("Log"),

    _("Log scale"),

    VIPS_ARGUMENT_OPTIONAL_INPUT,

    G_STRUCT_OFFSET(VipsScale, log),

    FALSE);

  VIPS_ARG_DOUBLE(class, "exp", 3,

    _("Exponent"),

    _("Exponent for log scale"),

    VIPS_ARGUMENT_OPTIONAL_INPUT,

    G_STRUCT_OFFSET(VipsScale, exp),

    0.00001, 10000, 0.25);

}

static void

vips_scale_init(VipsScale *scale)

{

  scale->exp = 0.25;

}

/**

 * vips_scale: (method)

 * @in: input image

 * @out: (out): output image

 * @...: `NULL`-terminated list of optional named arguments

 *

 * Search the image for the maximum and minimum value, then return the image

 * as unsigned 8-bit, scaled so that the maximum value is 255 and the

 * minimum is zero.

 *

 * If @log is set, transform with log10(1.0 + pow(x, @exp)) + .5,

 * then scale so max == 255. By default, @exp is 0.25.

 *

 * ::: tip "Optional arguments"

 *     * @log: `gboolean`, log scale pixels

 *     * @exp: `gdouble`, exponent for log scale

 *

 * ::: seealso

 *     [method@Image.cast].

 *

 * Returns: 0 on success, -1 on error

 */

int

vips_scale(VipsImage *in, VipsImage **out, ...)

{

  va_list ap;

  int result;

  va_start(ap, out);

  result = vips_call_split("scale", ap, in, out);

  va_end(ap);

  return result;

}