path: root/src/libclut.h

/**
 * Copyright © 2016  Mattias Andrée <maandree@member.fsf.org>
 * 
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 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 General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
#ifndef LIBCLUT_H
#define LIBCLUT_H

#include <stddef.h>
#include <string.h>
#include <math.h>



/**
 * Apply contrast correction on the colour curves using sRGB.
 * 
 * In this context, contrast is a measure of difference between
 * the whitepoint and blackpoint, if the difference is 0 than
 * they are both grey.
 * 
 * None of the parameter may have side-effects.
 * 
 * @param  clut  Pointer to the gamma ramps, must have the arrays
 *               `red`, `green`, and `blue`, and the scalars
 *               `red_size`, `green_size`, and `blue_size`. Ramp
 *               structures from libgamma can be used.
 * @param  max   The maximum value on each stop in the ramps.
 * @param  type  The data type used for each stop in the ramps.
 * @param  r     The contrast parameter for the red curve.
 * @param  g     The contrast parameter for the green curve.
 * @param  b     The contrast parameter for the blue curve.
 */
#define libclut_rgb_contrast(clut, max, type, r, g, b)							\
  do													\
    {													\
      if ((r) != 1.0)  libclut__(clut, red,   type, LIBCLUT_VALUE - (max) * 0.5 * (r) + (max) * 0.5);	\
      if ((g) != 1.0)  libclut__(clut, green, type, LIBCLUT_VALUE - (max) * 0.5 * (g) + (max) * 0.5);	\
      if ((b) != 1.0)  libclut__(clut, blue,  type, LIBCLUT_VALUE - (max) * 0.5 * (b) + (max) * 0.5);	\
    }													\
  while (0)


/**
 * Apply contrast correction on the colour curves using CIE xyY.
 * 
 * In this context, contrast is a measure of difference between
 * the whitepoint and blackpoint, if the difference is 0 than
 * they are both grey.
 * 
 * None of the parameter may have side-effects.
 * 
 * Requires linking with '-lclut'.
 * 
 * @param  clut  Pointer to the gamma ramps, must have the arrays
 *               `red`, `green`, and `blue`, and the scalars
 *               `red_size`, `green_size`, and `blue_size`. Ramp
 *               structures from libgamma can be used.
 * @param  max   The maximum value on each stop in the ramps.
 * @param  type  The data type used for each stop in the ramps.
 * @param  r     The contrast parameter for the red curve.
 * @param  g     The contrast parameter for the green curve.
 * @param  b     The contrast parameter for the blue curve.
 */
#define libclut_cie_contrast(clut, max, type, r, g, b)						\
  libclut_cie__(clut, max, type, (r == g) && (g == b), (r) != 1.0, (g) != 1.0, (b) != 1.0,	\
		(Y__ - 0.5) * (r) + 0.5, (Y__ - 0.5) * (g) + 0.5, (Y__ - 0.5) * (b) + 0.5)


/**
 * Apply brightness correction on the colour curves using sRGB.
 *  
 * In this context, brightness is a measure of the whiteness of the whitepoint.
 * 
 * None of the parameter may have side-effects.
 * 
 * @param  clut  Pointer to the gamma ramps, must have the arrays
 *               `red`, `green`, and `blue`, and the scalars
 *               `red_size`, `green_size`, and `blue_size`. Ramp
 *               structures from libgamma can be used.
 * @param  max   The maximum value on each stop in the ramps.
 * @param  type  The data type used for each stop in the ramps.
 * @param  r     The brightness parameter for the red curve.
 * @param  g     The brightness parameter for the green curve.
 * @param  b     The brightness parameter for the blue curve.
 */
#define libclut_rgb_brightness(clut, max, type, r, g, b)			\
  do										\
    {										\
      if ((r) != 1.0)  libclut__(clut, red,   type, LIBCLUT_VALUE * (r));	\
      if ((g) != 1.0)  libclut__(clut, green, type, LIBCLUT_VALUE * (g));	\
      if ((b) != 1.0)  libclut__(clut, blue,  type, LIBCLUT_VALUE * (b));	\
    }										\
  while (0)


/**
 * Apply brightness correction on the colour curves using CIE xyY.
 *  
 * In this context, brightness is a measure of the whiteness of the whitepoint.
 * 
 * None of the parameter may have side-effects.
 * 
 * Requires linking with '-lclut'.
 * 
 * @param  clut  Pointer to the gamma ramps, must have the arrays
 *               `red`, `green`, and `blue`, and the scalars
 *               `red_size`, `green_size`, and `blue_size`. Ramp
 *               structures from libgamma can be used.
 * @param  max   The maximum value on each stop in the ramps.
 * @param  type  The data type used for each stop in the ramps.
 * @param  r     The brightness parameter for the red curve.
 * @param  g     The brightness parameter for the green curve.
 * @param  b     The brightness parameter for the blue curve.
 */
#define libclut_cie_brightness(clut, max, type, r, g, b)				\
  libclut_cie__(clut, max, type, ((r) == (g)) && ((g) == (b)),				\
		(r) != 1.0, (g) != 1.0, (b) != 1.0, Y__ * (r), Y__ * (g), Y__ * (b))


/**
 * Convert the curves from formatted in standard RGB to linear RGB.
 * 
 * None of the parameter may have side-effects.
 * 
 * Requires linking with '-lclut', or '-lm' if
 * `libclut_model_standard_to_linear1` is not undefined.
 * 
 * @param  clut  Pointer to the gamma ramps, must have the arrays
 *               `red`, `green`, and `blue`, and the scalars
 *               `red_size`, `green_size`, and `blue_size`. Ramp
 *               structures from libgamma can be used.
 * @param  max   The maximum value on each stop in the ramps.
 * @param  type  The data type used for each stop in the ramps.
 * @param  r     Whether to convert the red colour curve.
 * @param  g     Whether to convert the green colour curve.
 * @param  b     Whether to convert the blue colour curve.
 */
#define libclut_linearise(clut, max, type, r, g, b)							\
  do													\
    {													\
      double m__ = (double)(max);									\
      if (r)												\
	libclut__(clut, red,   type, m__ * libclut_model_standard_to_linear1(LIBCLUT_VALUE / m__));	\
      if (g)												\
	libclut__(clut, green, type, m__ * libclut_model_standard_to_linear1(LIBCLUT_VALUE / m__));	\
      if (b)												\
	libclut__(clut, blue,  type, m__ * libclut_model_standard_to_linear1(LIBCLUT_VALUE / m__));	\
    }													\
  while (0)


/**
 * Convert the curves from formatted in linear RGB to standard RGB.
 * 
 * None of the parameter may have side-effects.
 * 
 * Requires linking with '-lclut', or '-lm' if
 * `libclut_model_linear_to_standard1` is not undefined.
 * 
 * @param  clut  Pointer to the gamma ramps, must have the arrays
 *               `red`, `green`, and `blue`, and the scalars
 *               `red_size`, `green_size`, and `blue_size`. Ramp
 *               structures from libgamma can be used.
 * @param  max   The maximum value on each stop in the ramps.
 * @param  type  The data type used for each stop in the ramps.
 * @param  r     Whether to convert the red colour curve.
 * @param  g     Whether to convert the green colour curve.
 * @param  b     Whether to convert the blue colour curve.
 */
#define libclut_standardise(clut, max, type, r, g, b)							\
  do													\
    {													\
      double m__ = (double)(max);									\
      if (r)												\
	libclut__(clut, red,   type, m__ * libclut_model_linear_to_standard1(LIBCLUT_VALUE / m__));	\
      if (g)												\
	libclut__(clut, green, type, m__ * libclut_model_linear_to_standard1(LIBCLUT_VALUE / m__));	\
      if (b)												\
	libclut__(clut, blue,  type, m__ * libclut_model_linear_to_standard1(LIBCLUT_VALUE / m__));	\
    }													\
  while (0)


/**
 * Apply gamma correction on the colour curves.
 * 
 * None of the parameter may have side-effects.
 * 
 * Requires linking with '-lm'.
 * 
 * @param  clut  Pointer to the gamma ramps, must have the arrays
 *               `red`, `green`, and `blue`, and the scalars
 *               `red_size`, `green_size`, and `blue_size`. Ramp
 *               structures from libgamma can be used.
 * @param  max   The maximum value on each stop in the ramps.
 * @param  type  The data type used for each stop in the ramps.
 * @param  r     The gamma parameter the red colour curve.
 * @param  g     The gamma parameter the green colour curve.
 * @param  b     The gamma parameter the blue colour curve.
 */
#define libclut_gamma(clut, max, type, r, g, b)							\
  do												\
    {												\
      double m__ = (double)(max);								\
      if (r != 1.0)  libclut__(clut, red,   type, m__ * pow(LIBCLUT_VALUE / m__, 1.0 / (r)));	\
      if (g != 1.0)  libclut__(clut, green, type, m__ * pow(LIBCLUT_VALUE / m__, 1.0 / (g)));	\
      if (b != 1.0)  libclut__(clut, blue,  type, m__ * pow(LIBCLUT_VALUE / m__, 1.0 / (b)));	\
    }												\
  while (0)


/**
 * Reverse the colour curves (negative image with gamma preservation.)
 * 
 * None of the parameter may have side-effects.
 * 
 * @param  clut  Pointer to the gamma ramps, must have the arrays
 *               `red`, `green`, and `blue`, and the scalars
 *               `red_size`, `green_size`, and `blue_size`. Ramp
 *               structures from libgamma can be used.
 * @param  max   The maximum value on each stop in the ramps.
 *               This parameter is not used, it is just a dummy, to unify
 *               the API with the other functions.
 * @param  type  The data type used for each stop in the ramps.
 * @param  r     Whether to invert the red colour curve.
 * @param  g     Whether to invert the green colour curve.
 * @param  b     Whether to invert the blue colour curve.
 */
#define libclut_negative(clut, max, type, r, g, b)				\
  do										\
    {										\
      size_t i__, n__;								\
      type t__;									\
      if (r)									\
	for (i__ = 0, n__ = (clut)->red_size; i__ < (n__ >> 1); i__++)		\
	  {									\
	    t__ = (clut)->red[i__];						\
	    (clut)->red[i__] = (clut)->red[n__ - i__ - 1];			\
	    (clut)->red[n__ - i__ - 1] = t__;					\
	  }									\
      if (g)									\
	for (i__ = 0, n__ = (clut)->green_size; i__ < (n__ >> 1); i__++)	\
	  {									\
	    t__ = (clut)->green[i__];						\
	    (clut)->green[i__] = (clut)->green[n__ - i__ - 1];			\
	    (clut)->green[n__ - i__ - 1] = t__;					\
	  }									\
      if (b)									\
	for (i__ = 0, n__ = (clut)->blue_size; i__ < (n__ >> 1); i__++)		\
	  {									\
	    t__ = (clut)->blue[i__];						\
	    (clut)->blue[i__] = (clut)->blue[n__ - i__ - 1];			\
	    (clut)->blue[n__ - i__ - 1] = t__;					\
	  }									\
    }										\
  while (0)


/**
 * Invert the colour curves (negative image with gamma invertion), using sRGB.
 * 
 * None of the parameter may have side-effects.
 * 
 * @param  clut  Pointer to the gamma ramps, must have the arrays
 *               `red`, `green`, and `blue`, and the scalars
 *               `red_size`, `green_size`, and `blue_size`. Ramp
 *               structures from libgamma can be used.
 * @param  max   The maximum value on each stop in the ramps.
 * @param  type  The data type used for each stop in the ramps.
 * @param  r     Whether to invert the red colour curve.
 * @param  g     Whether to invert the green colour curve.
 * @param  b     Whether to invert the blue colour curve.
 */
#define libclut_rgb_invert(clut, max, type, r, g, b)			\
  do									\
    {									\
      if (r)  libclut__(clut, red,   type, (max) - LIBCLUT_VALUE);	\
      if (g)  libclut__(clut, green, type, (max) - LIBCLUT_VALUE);	\
      if (b)  libclut__(clut, blue,  type, (max) - LIBCLUT_VALUE);	\
    }									\
  while (0)


/**
 * Invert the colour curves (negative image with gamma invertion), using CIE xyY.
 * 
 * None of the parameter may have side-effects.
 * 
 * Requires linking with '-lclut'.
 * 
 * @param  clut  Pointer to the gamma ramps, must have the arrays
 *               `red`, `green`, and `blue`, and the scalars
 *               `red_size`, `green_size`, and `blue_size`. Ramp
 *               structures from libgamma can be used.
 * @param  max   The maximum value on each stop in the ramps.
 * @param  type  The data type used for each stop in the ramps.
 * @param  r     Whether to invert the red colour curve.
 * @param  g     Whether to invert the green colour curve.
 * @param  b     Whether to invert the blue colour curve.
 */
#define libclut_cie_invert(clut, max, type, r, g, b)						\
  libclut_cie__(clut, max, type, (r) && (g) && (b), r, g, b, 1.0 - Y__, 1.0 - Y__, 1.0 - Y__)


/**
 * Apply S-curve correction on the colour curves.
 * This is intended for fine tuning LCD monitors,
 * 4.5 is good value start start testing at.
 * You would probably like to use rgb_limits before
 * this to adjust the blackpoint as that is the
 * only way to adjust the blackpoint on many LCD
 * monitors.
 * 
 * None of the parameter may have side-effects.
 * 
 * Requires linking with '-lm'.
 * 
 * @param  clut  Pointer to the gamma ramps, must have the arrays
 *               `red`, `green`, and `blue`, and the scalars
 *               `red_size`, `green_size`, and `blue_size`. Ramp
 *               structures from libgamma can be used.
 * @param  max   The maximum value on each stop in the ramps.
 * @param  type  The data type used for each stop in the ramps.
 * @param  rp    Pointer to the sigmoid parameter for the red curve. `NULL` for no adjustment.
 * @param  gp    Pointer to the sigmoid parameter for the green curve. `NULL` for no adjustment.
 * @param  bp    Pointer to the sigmoid parameter for the blue curve. `NULL` for no adjustment.
 */
#define libclut_sigmoid(clut, max, type, rp, gp, bp)							\
  do													\
    {													\
      double r__ = (rp) ? *(rp) : 0.0;									\
      double g__ = (gp) ? *(gp) : 0.0;									\
      double b__ = (bp) ? *(bp) : 0.0;									\
      double m__ = (double)(max);									\
      size_t i__;											\
      if (rp)												\
	for (i__ = 0; i++ < (clut)->red_size; i__++)							\
	  if ((clut)->red[i__] && ((clut)->red[i__] != (max)))						\
	    (clut)->red[i__] = (type)(m__ * (0.5 - log(m__ / (clut)->red[i__] - 1.0) / r__));		\
      if (gp)												\
	for (i__ = 0; i++ < (clut)->green_size; i__++)							\
	  if ((clut)->green[i__] && ((clut)->green[i__] != (max)))					\
	    (clut)->green[i__] = (type)(m__ * (0.5 - log(m__ / (clut)->green[i__] - 1.0) / g__));	\
      if (bp)												\
	for (i__ = 0; i++ < (clut)->blue_size; i__++)							\
	  if ((clut)->blue[i__] && ((clut)->blue[i__] != (max)))					\
	    (clut)->blue[i__] = (type)(m__ * (0.5 - log(m__ / (clut)->blue[i__] - 1.0) / b__));		\
    }													\
  while (0)


/**
 * Changes the blackpoint and the whitepoint, using sRGB.
 * 
 * None of the parameter may have side-effects.
 * 
 * @param  clut  Pointer to the gamma ramps, must have the arrays
 *               `red`, `green`, and `blue`, and the scalars
 *               `red_size`, `green_size`, and `blue_size`. Ramp
 *               structures from libgamma can be used.
 * @param  max   The maximum value on each stop in the ramps.
 * @param  type  The data type used for each stop in the ramps.
 * @param  rmin  The red component value of the blackpoint.
 * @param  rmax  The red component value of the whitepoint.
 * @param  gmin  The green component value of the blackpoint.
 * @param  gmax  The green component value of the whitepoint.
 * @param  bmin  The blue component value of the blackpoint.
 * @param  bmax  The blue component value of the whitepoint.
 */
#define libclut_rgb_limits(clut, max, type, rmin, rmax, gmin, gmax, bmin, bmax)			\
  do												\
    {												\
      double diff__;										\
      if ((rmin != 0.0) || (rmax != 1.0))							\
	{											\
	  diff__ = (double)(rmax) - (double)(rmin);						\
	  libclut__(clut, red, type, LIBCLUT_VALUE / (double)(max) * diff__ + (rmin));		\
	}											\
      if ((gmin != 0.0) || (gmax != 1.0))							\
	{											\
	  diff__ = (double)(gmax) - (double)(gmin);						\
	  libclut__(clut, green, type, LIBCLUT_VALUE / (double)(max) * diff__ + (gmin));	\
	}											\
      if ((bmin != 0.0) || (bmax != 1.0))							\
	{											\
	  diff__ = (double)(bmax) - (double)(bmin);						\
	  libclut__(clut, blue, type, LIBCLUT_VALUE / (double)(max) * diff__ + (bmin));		\
	}											\
    }												\
  while (0)


/**
 * Changes the blackpoint and the whitepoint, using CIE xyY.
 * 
 * None of the parameter may have side-effects.
 * 
 * Requires linking with '-lclut'.
 * 
 * @param  clut  Pointer to the gamma ramps, must have the arrays
 *               `red`, `green`, and `blue`, and the scalars
 *               `red_size`, `green_size`, and `blue_size`. Ramp
 *               structures from libgamma can be used.
 * @param  max   The maximum value on each stop in the ramps.
 * @param  type  The data type used for each stop in the ramps.
 * @param  rmin  The red component value of the blackpoint.
 * @param  rmax  The red component value of the whitepoint.
 * @param  gmin  The green component value of the blackpoint.
 * @param  gmax  The green component value of the whitepoint.
 * @param  bmin  The blue component value of the blackpoint.
 * @param  bmax  The blue component value of the whitepoint.
 */
#define libclut_cie_limits(clut, max, type, rmin, rmax, gmin, gmax, bmin, bmax)				\
  do													\
    {													\
      double rd__ = (rmax) - (rmin), gd__ = (gmax) - (gmin), bd__ = (bmax) - (bmin);			\
      libclut_cie__(clut, max, type, ((rmin) == (gmin)) && ((gmin) == (bmin)) &&			\
		    ((rmax) == (gmax)) && ((gmax) == (bmax)), ((rmin) != 0.0) || ((rmax) != 1.0),	\
		    ((gmin) != 0.0) || ((gmax) != 1.0), ((bmin) != 0.0) || ((bmax) != 1.0),		\
		    Y__ * rd__ + (rmin), Y__ * gd__ + (gmin), Y__ * bd__ + (bmin));			\
    }													\
  while (0)


/**
 * Manipulate the colour curves using a function on the sRGB colour space.
 * 
 * None of the parameter may have side-effects.
 * 
 * @param  clut  Pointer to the gamma ramps, must have the arrays
 *               `red`, `green`, and `blue`, and the scalars
 *               `red_size`, `green_size`, and `blue_size`. Ramp
 *               structures from libgamma can be used.
 * @param  max   The maximum value on each stop in the ramps.
 * @param  type  The data type used for each stop in the ramps.
 * @param  r     Function to manipulate the red colour curve, should either
 *               be `NULL` or map a [0, 1] `double` to a [0, 1] `double`.
 * @param  g     Function to manipulate the green colour curve, should either
 *               be `NULL` or map a [0, 1] `double` to a [0, 1] `double`.
 * @param  b     Function to manipulate the blue colour curve, should either
 *               be `NULL` or map a [0, 1] `double` to a [0, 1] `double`.
 */
#define libclut_manipulate(clut, max, type, r, g, b)				\
  do										\
    {										\
      double m__ = (double)(max);						\
      if (r)  libclut__(clut, red,   type, m__ * (r)(LIBCLUT_VALUE / m__));	\
      if (g)  libclut__(clut, green, type, m__ * (g)(LIBCLUT_VALUE / m__));	\
      if (b)  libclut__(clut, blue,  type, m__ * (b)(LIBCLUT_VALUE / m__));	\
    }										\
  while (0)


/**
 * Manipulate the colour curves using a function on the CIE xyY colour space.
 * 
 * None of the parameter may have side-effects.
 * 
 * Requires linking with '-lclut'.
 * 
 * @param  clut  Pointer to the gamma ramps, must have the arrays
 *               `red`, `green`, and `blue`, and the scalars
 *               `red_size`, `green_size`, and `blue_size`. Ramp
 *               structures from libgamma can be used.
 * @param  max   The maximum value on each stop in the ramps.
 * @param  type  The data type used for each stop in the ramps.
 * @param  r     Function to manipulate the red colour curve, should either
 *               be `NULL` or map a [0, 1] `double` to a [0, 1] `double`.
 * @param  g     Function to manipulate the green colour curve, should either
 *               be `NULL` or map a [0, 1] `double` to a [0, 1] `double`.
 * @param  b     Function to manipulate the blue colour curve, should either
 *               be `NULL` or map a [0, 1] `double` to a [0, 1] `double`.
 */
#define libclut_cie_manipulate(clut, max, type, r, g, b)					\
  libclut_cie__(clut, max, type, (r) && (g) && (b), r, g, b, (r)(Y__), (g)(Y__), (b)(Y__))


/**
 * Resets colour curvers to linear mappings.
 * (Identity mapping if imaginged to map from [0, 1] to [0, 1].)
 * 
 * None of the parameter may have side-effects.
 * 
 * @param  clut  Pointer to the gamma ramps, must have the arrays
 *               `red`, `green`, and `blue`, and the scalars
 *               `red_size`, `green_size`, and `blue_size`. Ramp
 *               structures from libgamma can be used.
 * @param  max   The maximum value on each stop in the ramps.
 * @param  type  The data type used for each stop in the ramps.
 * @param  r     Whether to reset the red colour curve.
 * @param  g     Whether to reset the green colour curve.
 * @param  b     Whether to reset the blue colour curve.
 */
#define libclut_start_over(clut, max, type, r, g, b)		\
  do								\
    {								\
      size_t i__;						\
      double m__;						\
      if (r)							\
	{							\
	  m__ = (double)((clut)->red_size - 1);			\
	  for (i__ = 0; i__ < (clut)->red_size; i__++)		\
	    (clut)->red[i__] = (type)((i__ / m__) * (max));	\
	}							\
      if (g)							\
	{							\
	  m__ = (double)((clut)->green_size - 1);		\
	  for (i__ = 0; i__ < (clut)->green_size; i__++)	\
	    (clut)->green[i__] = (type)((i__ / m__) * (max));	\
	}							\
      if (b)							\
	{							\
	  m__ = (double)((clut)->blue_size - 1);		\
	  for (i__ = 0; i__ < (clut)->blue_size; i__++)		\
	    (clut)->blue[i__] = (type)((i__ / m__) * (max));	\
	}							\
    }								\
  while (0)


/**
 * Clip colour curves to only map to values between the minimum and maximum.
 * This should be done, before apply the curves, and before applying changes
 * with limited domain.
 * 
 * Values below 0 are set to 0, and values above `max` are set to `max`.
 * 
 * None of the parameter may have side-effects.
 * 
 * @param  clut  Pointer to the gamma ramps, must have the arrays
 *               `red`, `green`, and `blue`, and the scalars
 *               `red_size`, `green_size`, and `blue_size`. Ramp
 *               structures from libgamma can be used.
 * @param  max   The maximum value on each stop in the ramps.
 * @param  type  The data type used for each stop in the ramps.
 * @param  r     Whether to clip the red colour curve.
 * @param  g     Whether to clip the green colour curve.
 * @param  b     Whether to clip the blue colour curve.
 */
#define libclut_clip(clut, max, type, r, g, b)						\
  do											\
    {											\
      if (r)  libclut__(clut, red,   type, libclut_clip__(0, LIBCLUT_VALUE, max));	\
      if (g)  libclut__(clut, green, type, libclut_clip__(0, LIBCLUT_VALUE, max));	\
      if (b)  libclut__(clut, blue,  type, libclut_clip__(0, LIBCLUT_VALUE, max));	\
    }											\
  while (0)

/**
 * Truncates a value to fit a boundary.
 * 
 * None of the parameter may have side-effects.
 * 
 * Intended for internal use.
 * 
 * @param   min  The minimum allowed value.
 * @param   val  The current value.
 * @param   max  The maximum allowed value.
 * @return       The value truncated into its boundary.
 */
#define libclut_clip__(min, val, max)							\
  (LIBCLUT_VALUE < (min) ? (min) : LIBCLUT_VALUE > (max) ? (max) : LIBCLUT_VALUE)


/**
 * Emulates low colour resolution.
 * 
 * None of the parameter may have side-effects.
 * 
 * @param  clut  Pointer to the gamma ramps, must have the arrays
 *               `red`, `green`, and `blue`, and the scalars
 *               `red_size`, `green_size`, and `blue_size`. Ramp
 *               structures from libgamma can be used.
 * @param  max   The maximum value on each stop in the ramps.
 * @param  type  The data type used for each stop in the ramps.
 * @param  rx    The desired emulated red encoding resolution, 0 for unchanged.
 * @param  ry    The desired emulated red output resolution, 0 for unchanged.
 * @param  gx    The desired emulated green encoding resolution, 0 for unchanged.
 * @param  gy    The desired emulated green output resolution, 0 for unchanged.
 * @param  bx    The desired emulated blue encoding resolution, 0 for unchanged.
 * @param  by    The desired emulated blue output resolution, 0 for unchanged.
 */
#define libclut_lower_resolution(clut, max, type, rx, ry, gx, gy, bx, by)	\
  do										\
    {										\
      libclut_lower_resolution__(clut, red,   max, type, rx, ry);		\
      libclut_lower_resolution__(clut, green, max, type, gx, gy);		\
      libclut_lower_resolution__(clut, blue,  max, type, bx, by);		\
    }										\
  while (0)


/**
 * Emulates low colour resolution of a channel.
 * 
 * None of the parameter may have side-effects.
 * 
 * Intended for internal use.
 * 
 * @param  clut     Pointer to the gamma ramps, must have the arrays
 *                  `red`, `green`, and `blue`, and the scalars
 *                  `red_size`, `green_size`, and `blue_size`. Ramp
 *                  structures from libgamma can be used.
 * @param  channel  The channel, must be either "red", "green", or "blue".
 * @param  max      The maximum value on each stop in the ramps.
 * @param  type     The data type used for each stop in the ramps.
 * @param  x        The desired emulated encoding resolution, 0 for unchanged.
 * @param  y        The desired emulated output resolution, 0 for unchanged.
 */
#define libclut_lower_resolution__(clut, channel, max, type, x, y)			\
  do											\
    {											\
      if ((x) || (y))									\
	{										\
	  size_t x__, y__, i__, n__ = (clut)->channel##_size;				\
	  double xm__ = (double)((x) - 1), ym__ = (double)((y) - 1);			\
	  double m__ = (double)(max);							\
	  type c__[n__]; /* Do not use alloca! */					\
	  for (i__ = 0; i__ < n__; i__++)						\
	    {										\
	      if ((x__ = i__), (x))							\
		{									\
		  x__ = (size_t)((double)i__ * (x) / n__);				\
		  x__ = (size_t)((double)x__ * i__ / xm__);				\
		}									\
	      if (!(y))									\
		c__[i__] = (clut)->channel[x__];					\
	      else									\
		{									\
		  y__ = (size_t)((double)((clut)->channel[x__]) / (max) * ym__ + 0.5);	\
		  c__[i__] = (type)((double)y__ / ym__ * m__);				\
		}									\
	    }										\
	  memcpy((clut)->channel, c__, n__ * sizeof(type));				\
	}										\
    }											\
  while (0)


/**
 * Applies a filter or calibration.
 * 
 * None of the parameter may have side-effects.
 * 
 * @param  clut    Pointer to the gamma ramps, must have the arrays
 *                 `red`, `green`, and `blue`, and the scalars
 *                 `red_size`, `green_size`, and `blue_size`. Ramp
 *                 structures from libgamma can be used.
 * @param  max     The maximum value on each stop in the ramps.
 * @param  type    The data type used for each stop in the ramps.
 * @param  filter  Same as `clut`, but for the filter to apply.
 * @param  fmax    Same as `max`, but for the filter to apply.
 * @param  ftype   Same as `type`, but for the filter to apply. (Not actually used).
 * @param  r       Whether to apply the filter for the red curve.
 * @param  g       Whether to apply the filter for the green curve.
 * @param  b       Whether to apply the filter for the blue curve.
 */
#define libclut_apply(clut, max, type, filter, fmax, ftype, r, g, b)		\
  do										\
    {										\
      if (r)  libclut_apply__(clut, max, type, filter, fmax, ftype, red);	\
      if (g)  libclut_apply__(clut, max, type, filter, fmax, ftype, green);	\
      if (b)  libclut_apply__(clut, max, type, filter, fmax, ftype, blue);	\
    }										\
  while (0)


/**
 * Applies a filter or calibration for one channel.
 * 
 * None of the parameter may have side-effects.
 * 
 * Intended for internal use.
 * 
 * @param  clut     Pointer to the gamma ramps, must have the arrays
 *                  `red`, `green`, and `blue`, and the scalars
 *                  `red_size`, `green_size`, and `blue_size`. Ramp
 *                  structures from libgamma can be used.
 * @param  max      The maximum value on each stop in the ramps.
 * @param  type     The data type used for each stop in the ramps.
 * @param  filter   Same as `clut`, but for the filter to apply.
 * @param  fmax     Same as `max`, but for the filter to apply.
 * @param  ftype    Same as `type`, but for the filter to apply. (Not actually used).
 * @param  channel  The channel, must be either "red", "green", or "blue".
 */
#define libclut_apply__(clut, max, type, filter, fmax, ftype, channel)			\
  do											\
    {											\
      size_t i__, rn__ = (clut)->channel##_size, fn__ = (filter)->channel##_size;	\
      size_t x__, rm__ = (double)(max), m__ = (double)(max) / (double)(fmax);		\
      for (i__ = 0; i__ < rn__; i__++)							\
	{										\
	  x__ = (size_t)((double)((clut)->channel[i__]) / rm__ * fn__);			\
	  (clut)->channel[i__] = (type)((double)((filter)->channel[x__]) * m__);	\
	}										\
    }											\
  while (0)


/**
 * Applies a filter or calibration, using CIE xyY.
 * 
 * None of the parameter may have side-effects.
 * 
 * Requires linking with '-lclut'.
 * 
 * @param  clut    Pointer to the gamma ramps, must have the arrays
 *                 `red`, `green`, and `blue`, and the scalars
 *                 `red_size`, `green_size`, and `blue_size`. Ramp
 *                 structures from libgamma can be used.
 * @param  max     The maximum value on each stop in the ramps.
 * @param  type    The data type used for each stop in the ramps.
 * @param  filter  Same as `clut`, but for the filter to apply.
 * @param  fmax    Same as `max`, but for the filter to apply.
 * @param  ftype   Same as `type`, but for the filter to apply. (Not actually used).
 * @param  r       Whether to apply the filter for the red curve.
 * @param  g       Whether to apply the filter for the green curve.
 * @param  b       Whether to apply the filter for the blue curve.
 */
#define libclut_cie_apply(clut, max, type, filter, fmax, ftype, r, g, b)				\
  do													\
    {													\
      size_t rfn__ = (filter)->red_size, gfn__ = (filter)->green_size;					\
      size_t bfn__ = (filter)->blue_size, x__;								\
      size_t rm__ = (double)(max), fm__ = (double)(fmax);						\
      libclut_cie__(clut, max, type, 0, r, g, b,							\
		    (x__ = (size_t)(Y__ / rm__ * rfn__), (double)((filter)->red[x__])   / fm__),	\
		    (x__ = (size_t)(Y__ / rm__ * gfn__), (double)((filter)->green[x__]) / fm__),	\
		    (x__ = (size_t)(Y__ / rm__ * bfn__), (double)((filter)->blue[x__])  / fm__));	\
    }													\
  while (0)


/**
 * Modify a ramp.
 * 
 * None of the parameter may have side-effects.
 * 
 * This is intended for internal use.
 * 
 * @param  clut     Pointer to the gamma ramps, must have and array
 *                  named `channel` and a scalar named `channel` followed
 *                  by "_size".
 * @param  channel  The channel, must be either "red", "green", or "blue".
 * @param  type     The data type used for each stop in the ramps.
 * @param  expr     Expression that evalutes the value a stop should have.
 *                  It can use the variable `LIBCLUT_VALUE` to get the
 *                  current value of the stop.
 */
#define libclut__(clut, channel, type, expr)		\
  do							\
    {							\
      size_t i__, n__ = (clut)->channel##_size;		\
      type LIBCLUT_VALUE;				\
      for (i__ = 0; i__ < n__; i__++)			\
	{						\
	  LIBCLUT_VALUE = (clut)->channel[i__];		\
	  (clut)->channel[i__] = (type)(expr);		\
	}						\
    }							\
  while (0)


/**
 * Modify a ramp set in CIE xyY.
 * 
 * None of the parameter may have side-effects.
 * 
 * Requires linking with '-lclut'.
 * 
 * This is intended for internal use.
 * 
 * @param  clut   Pointer to the gamma ramps, must have the arrays
 *                `red`, `green`, and `blue`, and the scalars
 *                `red_size`, `green_size`, and `blue_size`. Ramp
 *                structures from libgamma can be used.
 * @param  max    The maximum value on each stop in the ramps.
 * @param  type   The data type used for each stop in the ramps.
 * @param  utest  Whether all channels can be modified at the same time.
 *                This test does not have to include the ramp size.
 * @param  rtest  Whether the red channel have to be modified.
 * @param  gtest  Whether the green channel have to be modified.
 * @param  btest  Whether the blue channel have to be modified.
 * @param  rexpr  Expression calculating the intensity of the red channel.
 *                The current value is stored in `Y__`.
 * @param  gexpr  Expression calculating the intensity of the green channel.
 *                The current value is stored in `Y__`.
 * @param  bexpr  Expression calculating the intensity of the blue channel.
 *                The current value is stored in `Y__`.
 */
#define libclut_cie__(clut, max, type, utest, rtest, gtest, btest, rexpr, gexpr, bexpr)	\
  do											\
    {											\
      size_t rn__ = (clut)->red_size;							\
      size_t gn__ = (clut)->green_size;							\
      size_t bn__ = (clut)->blue_size;							\
      size_t i__;									\
      double x__, y__, Y__, r__, g__, b__;						\
      double m__ = (double)(max);							\
      type* rs__ = (clut)->red;								\
      type* gs__ = (clut)->green;							\
      type* bs__ = (clut)->blue;							\
      if ((rn__ == gn__) && (gn__ == bn__) && (utest))					\
	{										\
	  if (!(rtest))									\
	    break;									\
	  for (i__ = 0; i__ < rn__; i__++)						\
	    {										\
	      libclut_model_srgb_to_ciexyy(rs__[i__] / m__, gs__[i__] / m__,		\
					   bs__[i__] / m__, &x__, &y__, &Y__);		\
	      libclut_model_ciexyy_to_srgb(x__, y__, rexpr, &r__, &g__, &b__);		\
	      rs__[i__] = (type)(r__ * m__);						\
	      gs__[i__] = (type)(g__ * m__);						\
	      bs__[i__] = (type)(b__ * m__);						\
	    }										\
	}										\
      else if ((rn__ == gn__) && (gn__ == bn__))					\
	{										\
	  if (!(rtest) && !(gtest) && !(btest))						\
	    break;									\
	  for (i__ = 0; i__ < rn__; i__++)						\
	    {										\
	      libclut_model_srgb_to_ciexyy(rs__[i__] / m__, gs__[i__] / m__,		\
					   bs__[i__] / m__, &x__, &y__, &Y__);		\
	      if (rtest)								\
		{									\
		  libclut_model_ciexyy_to_srgb(x__, y__, rexpr, &r__, &g__, &b__);	\
		  rs__[i__] = (type)(r__ * m__);					\
		}									\
	      if (gtest)								\
		{									\
		  libclut_model_ciexyy_to_srgb(x__, y__, gexpr, &r__, &g__, &b__);	\
		  gs__[i__] = (type)(g__ * m__);					\
		}									\
	      if (btest)								\
		{									\
		  libclut_model_ciexyy_to_srgb(x__, y__, nexpr, &r__, &g__, &b__);	\
		  bs__[i__] = (type)(b__ * m__);					\
		}									\
	    }										\
	}										\
      else										\
	{										\
	  if (rtest)									\
	    for (i__ = 0; i__ < rn__; i__++)						\
	    libclut_cie___(clut, max, type, rexpr, i__,					\
			   libclut_i__(i__, rn__, gn__),				\
			   libclut_i__(i__, rn__, bn__));				\
	  if (gtest)									\
	    for (i__ = 0; i__ < rn__; i__++)						\
	    libclut_cie___(clut, max, type, gexpr,					\
			   libclut_i__(i__, gn__, rn__), i__,				\
			   libclut_i__(i__, gn__, bn__));				\
	  if (btest)									\
	    for (i__ = 0; i__ < rn__; i__++)						\
	    libclut_cie___(clut, max, type, bexpr, i__,					\
			   libclut_i__(i__, bn__, rn__),				\
			   libclut_i__(i__, bn__, gn__), i__);				\
	}										\
    }											\
  while (0)


/**
 * Modify a ramp stop in CIE xyY.
 * 
 * None of the parameter may have side-effects.
 * 
 * Requires linking with '-lclut'.
 * 
 * This is intended for internal use.
 * Assumes the existence of variables defined in `libclut_cie__`.
 * 
 * @param  clut  Pointer to the gamma ramps, must have the arrays
 *               `red`, `green`, and `blue`, and the scalars
 *               `red_size`, `green_size`, and `blue_size`. Ramp
 *               structures from libgamma can be used.
 * @param  max   The maximum value on each stop in the ramps.
 * @param  type  The data type used for each stop in the ramps.
 * @param  c     Either "r" for red, "g" for green, or "b" for blue.
 * @param  expr  Expression calculating the intensity of the channel.
 * @param  ri    The index of the stop translated to the red channel.
 * @param  gi    The index of the stop translated to the green channel.
 * @param  bi    The index of the stop translated to the blue channel.
 */
#define libclut_cie___(clut, max, type, c, expr, ri, gi, bi)			\
  do										\
    {										\
      for (i__ = 0; i__ < c##n__; i__++)					\
	{									\
	  libclut_model_srgb_to_ciexyy(rs__[(ri)] / m__, gs__[(gi)] / m__,	\
				       bs__[(bi)] / m__, &x__, &y__, &Y__);	\
	  libclut_model_ciexyy_to_srgb(x__, y__, expr, &r__, &g__, &b__);	\
	  c##s__[i__] = (type)(c##__ * m__);					\
	}									\
    }										\
  while (0)


/**
 * Translate an index from one channel to another.
 * 
 * @param   i    The index in the input channel.
 * @param   in   The size of the input channel.
 * @param   out  The size of the output channel.
 * @return       The index in the output channel.
 */
#define libclut_i__(i, in, out)				\
  (size_t)((double)(i) * (double)(out) / (double)(in))



#if __GNUC__
#define LIBCLUT_GCC_ONLY__(x)  x
#else
#define LIBCLUT_GCC_ONLY__(x)  /* do nothing */
#endif



/**
 * Convert one component from [0, 1] linear RGB to [0, 1] sRGB.
 * 
 * If the macro variant is used, the argument must not have
 * any side-effects. The macro variant requires linking with
 * '-lm'.
 * 
 * @param   c  The linear RGB value.
 * @return     Corresponding sRGB value.
 */
LIBCLUT_GCC_ONLY__(__attribute__((__const__, __leaf__)))
double (libclut_model_linear_to_standard1)(double);
#define libclut_model_linear_to_standard1(c)  \
  (((double)(c) <= 0.0031308) ? (12.92 * (double)(c)) : ((1.0 + 0.055) * pow((double)(c), 1.0 / 2.4)))


/**
 * Convert [0, 1] linear RGB to [0, 1] sRGB.
 * 
 * The macro variant requires linking with '-lm',
 * if the 'libclut_model_linear_to_standard1' is defined,
 * otherwise it requires linking with '-lclut'.
 * 
 * @param  r  Pointer to the linear red component,
 *            and output parameter for the red component.
 * @param  g  Pointer to the linear green component,
 *            and output parameter for the green component.
 * @param  b  Pointer to the linear blue component,
 *            and output parameter for the blue component.
 */
void (libclut_model_linear_to_standard)(double*, double*, double*);
#define libclut_model_linear_to_standard(r, g, b)	\
  do							\
    {							\
      double *r__ = (r), *g__ = (g), *b__ = (b);	\
      *r__ = libclut_model_linear_to_standard1(*r__);	\
      *g__ = libclut_model_linear_to_standard1(*g__);	\
      *b__ = libclut_model_linear_to_standard1(*b__);	\
    }							\
  while (0)


/**
 * Convert one component from [0, 1] sRGB to [0, 1] linear RGB.
 * 
 * If the macro variant is used, the argument must not have
 * any side-effects. The macro variant requires linking with
 * '-lm'.
 * 
 * @param   c  The sRGB value.
 * @return     Corresponding linear RGB value.
 */
LIBCLUT_GCC_ONLY__(__attribute__((__const__, __leaf__)))
double (libclut_model_standard_to_linear1)(double);
#define libclut_model_standard_to_linear1(c)  \
  (((double)(c) <= 0.04045) ? ((double)(c) / 12.92) : pow(((double)(c) + 0.055) / (1.0 + 0.055), 2.4))


/**
 * Convert [0, 1] sRGB to [0, 1] linear RGB.
 * 
 * The macro variant requires linking with '-lm',
 * if the 'libclut_model_standard_to_linear1' is defined,
 * otherwise it requires linking with '-lclut'.
 * 
 * @param  r  Pointer to the red component, and output
 *            parameter for the linear red component.
 * @param  g  Pointer to the green component, and output
 *            parameter for the linear green component.
 * @param  b  Pointer to the blue component, and output
 *            parameter for the linear blue component.
 */
void (libclut_model_standard_to_linear)(double*, double*, double*);
#define libclut_model_standard_to_linear(r, g, b)	\
  do							\
    {							\
      double *r__ = (r), *g__ = (g), *b__ = (b);	\
      *r__ = libclut_model_standard_to_linear1(*r__);	\
      *g__ = libclut_model_standard_to_linear1(*g__);	\
      *b__ = libclut_model_standard_to_linear1(*b__);	\
    }							\
  while (0)


/**
 * Convert CIE xyY to CIE XYZ.
 * 
 * @param  x  The x parameter.
 * @param  y  The y parameter.
 * @param  Y  The Y parameter. This is also the Y (middle) parameter for the CIE XYZ colour.
 * @param  X  Output parameter for the X parameter.
 * @param  Z  Output parameter for the Z parameter.
 */
LIBCLUT_GCC_ONLY__(__attribute__((__leaf__)))
void (libclut_model_ciexyy_to_ciexyz)(double, double, double, double*, double*);
#define libclut_model_ciexyy_to_ciexyz(x, y, Y, X, Z)			\
  do									\
    {									\
      double x__ = (x), y__ = (y), Y__ = (Y), *X__ = (X), *Z__ = (Z);	\
      *X__ = (y__ == 0.0) ? Y__ : (Y__ * x__ / y__);			\
      *Z__ = (y__ == 0.0) ? Y__ : (Y__ * (1.0 - x__ - y__) / y__);	\
    }									\
  while (0)


/**
 * Convert CIE XYZ to CIE xyY.
 * 
 * @param  X  The X parameter.
 * @param  Y  The Y parameter. This is also the Y (last) parameter for the CIE xyY colour.
 * @param  Z  The Z parameter.
 * @param  x  Output parameter for the x parameter.
 * @param  y  Output parameter for the y parameter.
 */
LIBCLUT_GCC_ONLY__(__attribute__((__leaf__)))
void (libclut_model_ciexyz_to_ciexyy)(double, double, double, double*, double*);
#define libclut_model_ciexyz_to_ciexyy(X, Y, Z, x, y)			\
  do									\
    {									\
      double X__ = (X), Y__ = (Y), Z__ = (Z), *x__ = (x), *y__ = (y);	\
      double s__ = X__ + Y__ + Z__;					\
      if (s__ == 0.0)							\
	*x__ = *y__ = 0.0;						\
      else								\
	*x__ = X__ / s__, *y__ = Y__ / s__;				\
    }									\
  while (0)


/**
 * Convert CIE XYZ to [0, 1] linear RGB.
 * 
 * @param  X  The X parameter.
 * @param  Y  The Y parameter.
 * @param  Z  The Z parameter.
 * @param  r  Output parameter for the red component.
 * @param  g  Output parameter for the green component.
 * @param  b  Output parameter for the blue component.
 */
LIBCLUT_GCC_ONLY__(__attribute__((__leaf__)))
void (libclut_model_ciexyz_to_linear)(double, double, double, double*, double*, double*);
#define libclut_model_ciexyz_to_linear(X, Y, Z, r, g, b)			\
  do										\
    {										\
      double X__ = (X), Y__ = (Y), Z__ = (Z);					\
      *(r) = ( 3.2404500 * X__) + (-1.537140 * Y__) + (-0.4985320 * Z__);	\
      *(g) = (-0.9692660 * X__) + ( 1.876010 * Y__) + ( 0.0415561 * Z__);	\
      *(b) = ( 0.0556434 * X__) + (-0.204026 * Y__) + ( 1.0572300 * Z__);	\
    }										\
  while (0)


/**
 * Convert [0, 1] linear RGB to CIE XYZ.
 * 
 * @param  r  The red component.
 * @param  g  The green component.
 * @param  b  The blue component.
 * @param  X  Output parameter for the X parameter.
 * @param  Y  Output parameter for the Y parameter.
 * @param  Z  Output parameter for the Z parameter.
 */
LIBCLUT_GCC_ONLY__(__attribute__((__leaf__)))
void (libclut_model_linear_to_ciexyz)(double, double, double, double*, double*, double*);
#define libclut_model_linear_to_ciexyz(r, g, b, X, Y, Z)			\
  do										\
    {										\
      double r__ = (r), g__ = (g), b__ = (b);					\
      *(X) = (0.4124564 * r__) + (0.3575761 * g__) + (0.1804375 * b__);		\
      *(Y) = (0.2126729 * r__) + (0.7151522 * g__) + (0.0721750 * b__);		\
      *(Z) = (0.0193339 * r__) + (0.1191920 * g__) + (0.9503041 * b__);		\
    }										\
  while (0)


/**
 * Convert [0, 1] linear RGB to CIE xyY.
 * 
 * The macro variant requires linking with '-lclut'
 * if any of `libclut_model_ciexyz_to_ciexyy`,
 * `libclut_model_linear_to_ciexyz`, and
 * `libclut_model_standard_to_linear` are undefined.
 * The macro variant requires linking with '-lm' if
 * neither `libclut_model_standard_to_linear` nor
 * `libclut_model_standard_to_linear1` are undefined.
 * 
 * @param  r  The red component.
 * @param  g  The green component.
 * @param  b  The blue component.
 * @param  x  Output parameter for the x parameter.
 * @param  y  Output parameter for the y parameter.
 * @param  Y  Output parameter for the Y parameter.
 */
void (libclut_model_srgb_to_ciexyy)(double, double, double, double*, double*, double*);
#define libclut_model_srgb_to_ciexyy(r, g, b, x, y, Y)				\
  do										\
    {										\
      double r___ = (r), g___ = (g), b___ = (b);				\
      double *x___ = (x), *y___ = (y), *Y___ = (Y);				\
      double X___, Z___;							\
      libclut_model_standard_to_linear(&r___, &g___, &b___);			\
      libclut_model_linear_to_ciexyz(r___, g___, b___, &X___, Y___, &Z___);	\
      libclut_model_ciexyz_to_ciexyy(X___, *Y___, Z___, x___, y___);		\
    }										\
  while (0)


/**
 * Convert CIE xyY to [0, 1] sRGB.
 * 
 * The macro variant requires linking with '-lclut'
 * if any of `libclut_model_ciexyy_to_ciexyz`,
 * `libclut_model_ciexyz_to_linear`, and
 * `libclut_model_linear_to_standard` are undefined.
 * The macro variant requires linking with '-lm' if
 * neither `libclut_model_linear_to_standard` nor
 * `libclut_model_linear_to_standard1` are undefined.
 * 
 * @param  x  The x parameter.
 * @param  y  The y parameter.
 * @param  Y  The Y parameter.
 * @param  r  Output parameter for the red component.
 * @param  g  Output parameter for the green component.
 * @param  b  Output parameter for the blue component.
 */
void (libclut_model_ciexyy_to_srgb)(double, double, double, double*, double*, double*);
#define libclut_model_ciexyy_to_srgb(x, y, Y, r, g, b)				\
  do										\
    {										\
      double x___ = (x), y___ = (y), Y___ = (Y);				\
      double *r___ = (r), *g___ = (g), *b___ = (b);				\
      double X___, Z___;							\
      libclut_model_ciexyy_to_ciexyz(x___, y___, Y___, &X___, &Z___);		\
      libclut_model_ciexyz_to_linear(X___, Y___, Z___, r___, g___, b___);	\
      libclut_model_linear_to_standard(r___, g___, b___);			\
    }										\
  while(0)


/**
 * Convert from CIE XYZ to CIE L*a*b*.
 * 
 * The macro variant requires linking with '-lm'.
 * 
 * @param  X  The X parameter.
 * @param  Y  The Y parameter.
 * @param  Z  The Z parameter.
 * @param  L  Output parameter for the L* component.
 * @param  a  Output parameter for the a* component.
 * @param  b  Output parameter for the b* component.
 */
LIBCLUT_GCC_ONLY__(__attribute__((__leaf__)))
void (libclut_model_ciexyz_to_cielab)(double, double, double, double*, double*, double*);
#define libclut_model_ciexyz_to_cielab(X, Y, Z, L, a, b)	\
  do								\
    {								\
      double X__ = (X), Y__ = (Y), Z__ = (Z);			\
      X__ /= 0.95047, Z__ /= 1.08883;				\
      X__ = LIBCLUT_MODEL_CIEXYZ_TO_CIELAB__(X__);		\
      Y__ = LIBCLUT_MODEL_CIEXYZ_TO_CIELAB__(Y__);		\
      Z__ = LIBCLUT_MODEL_CIEXYZ_TO_CIELAB__(Z__);		\
      *(L) = 116.0 * Y__ - 16.0;				\
      *(a) = 500.0 * (X__ - Y__);				\
      *(b) = 200.0 * (Y__ - Z__);				\
    }								\
  while (0)
#define LIBCLUT_MODEL_CIEXYZ_TO_CIELAB__(C)  \
  (((C) > 0.00885642) ? pow((C), 1.0 / 3.0) : ((7.78 + 703.0 / 99900.0) * (C) + 0.1379310))


/**
 * Convert from CIE L*a*b* to CIE XYZ.
 * 
 * @param  L  The L* component.
 * @param  a  The a* component.
 * @param  b  The b* component.
 * @param  X  Output parameter for the X parameter.
 * @param  Y  Output parameter for the Y parameter.
 * @param  Z  Output parameter for the Z parameter.
 */
LIBCLUT_GCC_ONLY__(__attribute__((__leaf__)))
void (libclut_model_cielab_to_ciexyz)(double, double, double, double*, double*, double*);
#define libclut_model_cielab_to_ciexyz(L, a, b, X, Y, Z)	\
  do								\
    {								\
      double L__ = (L), a__ = (a), b__ = (b);			\
      double *X__ = (X), *Y__ = (Y), *Z__ = (Z);		\
      *Y__ = (L__ + 16.0) / 116.0;				\
      *X__ = a__ / 500.0 + *Y__;				\
      *Z__ = *Y__ - b__ / 200.0;				\
      *X__ = LIBCLUT_MODEL_CIELAB_TO_CIEXYZ__(*X__) * 0.95047;	\
      *Y__ = LIBCLUT_MODEL_CIELAB_TO_CIEXYZ__(*Y__);		\
      *Z__ = LIBCLUT_MODEL_CIELAB_TO_CIEXYZ__(*Z__) * 1.08883;	\
    }								\
  while (0)
#define LIBCLUT_MODEL_CIELAB_TO_CIEXYZ__(C)  \
  (((C)*(C)*(C) > 0.00885642) ? ((C)*(C)*(C)) : (((C) - 0.1379310) / (7.78 + 703.0 / 99900.0)))



#endif