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* Copyright (C) 2003 Fabien Chereau
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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// Class which converts tones in function of the eye adaptation to luminance.
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// The aim is to get on the screen something which is perceptualy accurate,
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// ie. to compress high dynamic range luminance to CRT display range.
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// The class perform mainly a fast implementation of the algorithm from the
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// paper [1], with more accurate values from [2]. The blue shift formula is taken
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// from [3] and combined with the Scotopic vision formula from [4].
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// Important : you may call set_display_adaptation_luminance()
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// and set_world_adaptation_luminance() before any call to xyY_to_RGB()
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// or adapt_luminance otherwise the default values will be used. (they are
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// appropriate for a daylight sky luminance)
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// Thanks to all the authors of the following papers i used for providing
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// their work freely online.
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// [1] "Tone Reproduction for Realistic Images", Tumblin and Rushmeier,
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// IEEE Computer Graphics & Application, November 1993
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// [2] "Tone Reproduction and Physically Based Spectral Rendering",
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// Devlin, Chalmers, Wilkie and Purgathofer in EUROGRAPHICS 2002
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// [3] "Night Rendering", H. Wann Jensen, S. Premoze, P. Shirley,
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// W.B. Thompson, J.A. Ferwerda, M.M. Stark
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// [4] "A Visibility Matching Tone Reproduction Operator for High Dynamic
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// Range Scenes", G.W. Larson, H. Rushmeier, C. Piatko
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#ifndef _TONE_REPRODUCTOR_H_
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#define _TONE_REPRODUCTOR_H_
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virtual ~ToneReproductor();
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// Set the eye adaptation luminance for the display (and precompute what can be)
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// Usual luminance range is 1-100 cd/m^2 for a CRT screen
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// default value = 50 cd/m^2
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void set_display_adaptation_luminance(float display_adaptation_luminance);
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// Set the eye adaptation luminance for the world (and precompute what can be)
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// default value = 40000 cd/m^2 for Skylight
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// Star Light : 0.001 cd/m^2
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// Moon Light : 0.1 cd/m^2
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// Indoor Lighting : 100 cd/m^2
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// Sun Light : 100000 cd/m^2
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void set_world_adaptation_luminance(float world_adaptation_luminance);
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// Set the maximum display luminance : default value = 100 cd/m^2
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// This value is used to scale the RGB range
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void set_max_display_luminance(float maxdL) {one_over_maxdL = 1.f/maxdL;}
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// Set the display gamma : default value = 2.3
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void set_display_gamma(float gamma) {one_over_gamma = 1.f/gamma;}
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// Return adapted luminance from world to display
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float adapt_luminance(float world_luminance) const
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return powf(world_luminance*M_PI*0.0001f,alpha_wa_over_alpha_da) * term2;
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// Convert from xyY color system to RGB
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void xyY_to_RGB(float*);
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float Lda; // Display luminance adaptation (in cd/m^2)
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float Lwa; // World luminance adaptation (in cd/m^2)
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float one_over_maxdL; // 1 / Display maximum luminance (in cd/m^2)
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float one_over_gamma; // 1 / Screen gamma value
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// Precomputed variables
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float alpha_wa_over_alpha_da;
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#endif // _TONE_REPRODUCTOR_H_
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src/tone_reproductor.h
