/* Oklab to XYZ.

 *

 */

/*

  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 <math.h>

#include <vips/vips.h>

#include <vips/debug.h>

#include "pcolour.h"

typedef VipsColourTransform VipsOklab2XYZ;

typedef VipsColourTransformClass VipsOklab2XYZClass;

G_DEFINE_TYPE(VipsOklab2XYZ, vips_Oklab2XYZ, VIPS_TYPE_COLOUR_TRANSFORM);

/* Process a buffer of data.

 */

static void

vips_Oklab2XYZ_line(VipsColour *colour, VipsPel *out, VipsPel **in, int width)

{

  float *restrict p = (float *) in[0];

  float *restrict q = (float *) out;

  for (int x = 0; x < width; x++) {

    const float L = p[0];

    const float a = p[1];

    const float b = p[2];

    p += 3;

    // M2 inv to get LMS prime

    const float lp = L * 1.         + a *  0.39633779 + b *  0.21580376;

    const float mp = L * 1.00000001 + a * -0.10556134 + b * -0.06385417;

    const float sp = L * 1.00000005 + a * -0.08948418 + b * -1.29148554;

    // back to lms

    const float l = lp * lp * lp;

    const float m = mp * mp * mp;

    const float s = sp * sp * sp;

    // M1 inv to get D65 normalised XYZ

    float X = l *  1.22701385 + m * -0.55779998 + s *  0.28125615;

    float Y = l * -0.04058018 + m *  1.11225687 + s * -0.07167668;

    float Z = l * -0.07638128 + m * -0.42148198 + s *  1.58616322;

    q[0] = X * 100.0;

    q[1] = Y * 100.0;

    q[2] = Z * 100.0;

    q += 3;

  }

}

static void

vips_Oklab2XYZ_class_init(VipsOklab2XYZClass *class)

{

  VipsObjectClass *object_class = (VipsObjectClass *) class;

  VipsColourClass *colour_class = VIPS_COLOUR_CLASS(class);

  object_class->nickname = "Oklab2XYZ";

  object_class->description = _("transform Oklab to XYZ");

  colour_class->process_line = vips_Oklab2XYZ_line;

}

static void

vips_Oklab2XYZ_init(VipsOklab2XYZ *Oklab2XYZ)

{

  VipsColour *colour = VIPS_COLOUR(Oklab2XYZ);

  colour->interpretation = VIPS_INTERPRETATION_XYZ;

}

/**

 * vips_Oklab2XYZ: (method)

 * @in: input image

 * @out: (out): output image

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

 *

 * Transform Oklab to XYZ using D65 illuminant.

 *

 * Returns: 0 on success, -1 on error

 */

int

vips_Oklab2XYZ(VipsImage *in, VipsImage **out, ...)

{

  va_list ap;

  int result;

  va_start(ap, out);

  result = vips_call_split("Oklab2XYZ", ap, in, out);

  va_end(ap);

  return result;

}