Stellarium 0.12.1
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StelToneReproducer Class Reference

Converts tones in function of the eye adaptation to luminance. More...

#include <StelToneReproducer.hpp>

Public Member Functions

 StelToneReproducer ()
 Constructor. More...
 
virtual ~StelToneReproducer ()
 Desctructor. More...
 
void setDisplayAdaptationLuminance (float displayAdaptationLuminance)
 Set the eye adaptation luminance for the display (and precompute what can be) Usual luminance range is 1-100 cd/m^2 for a CRT screen. More...
 
void setWorldAdaptationLuminance (float worldAdaptationLuminance)
 Set the eye adaptation luminance for the world (and precompute what can be) More...
 
float getWorldAdaptationLuminance () const
 Get the eye adaptation luminance for the world. More...
 
void setInputScale (float scale=1.f)
 Set the global scale applied to input lumiances, i.e before the adaptation It is the parameter to modify to simulate aperture*exposition time. More...
 
float getInputScale () const
 Get the global scale applied to input lumiances, i.e before the adaptation. More...
 
void setMaxDisplayLuminance (float maxdL)
 Set the maximum luminance of the display (CRT, screen etc..) This value is used to scale the RGB range. More...
 
float getDisplayGamma () const
 Get the display gamma. More...
 
void setDisplayGamma (float gamma)
 Set the display gamma. More...
 
float adaptLuminance (float worldLuminance) const
 Return adapted luminance from world to display. More...
 
float reverseAdaptLuminance (float displayLuminance) const
 Return adapted luminance from display to world. More...
 
float adaptLuminanceScaled (float worldLuminance) const
 Return adapted luminance from world to display with 1 corresponding to full display white. More...
 
float reverseAdaptLuminanceScaled (float displayLuminance) const
 Return adapted luminance from display to world with 1 corresponding to full display white. More...
 
float adaptLuminanceScaledLn (float lnWorldLuminance, float pFact=0.5f) const
 Return adapted ln(luminance) from world to display with 1 corresponding to full display white. More...
 
void xyYToRGB (float *xyY) const
 Convert from xyY color system to RGB. More...
 
void getShadersParams (float &a, float &b, float &c) const
 

Detailed Description

Converts tones in function of the eye adaptation to luminance.

The aim is to get on the screen something which is perceptualy accurate, ie. to compress high dynamic range luminance to CRT display range. The class perform mainly a fast implementation of the algorithm from the paper [1], with more accurate values from [2]. The blue shift formula is taken from [3] and combined with the Scotopic vision formula from [4].

Important : you may call setDisplayAdaptationLuminance() and setWorldAdaptationLuminance() before any call to xyYToRGB() or adaptLuminance otherwise the default values will be used. (they are appropriate for a daylight sky luminance)

REFERENCES : Thanks to all the authors of the following papers I used for providing their work freely online.

[1] "Tone Reproduction for Realistic Images", Tumblin and Rushmeier, IEEE Computer Graphics & Application, November 1993

[2] "Tone Reproduction and Physically Based Spectral Rendering", Devlin, Chalmers, Wilkie and Purgathofer in EUROGRAPHICS 2002

[3] "Night Rendering", H. Wann Jensen, S. Premoze, P. Shirley, W.B. Thompson, J.A. Ferwerda, M.M. Stark

[4] "A Visibility Matching Tone Reproduction Operator for High Dynamic Range Scenes", G.W. Larson, H. Rushmeier, C. Piatko

Definition at line 52 of file StelToneReproducer.hpp.

Constructor & Destructor Documentation

StelToneReproducer::StelToneReproducer ( )

Constructor.

virtual StelToneReproducer::~StelToneReproducer ( )
virtual

Desctructor.

Member Function Documentation

float StelToneReproducer::adaptLuminance ( float  worldLuminance) const
inline

Return adapted luminance from world to display.

Parameters
worldLuminancethe world luminance to convert in cd/m^2
Returns
the converted display luminance in cd/m^2

Definition at line 101 of file StelToneReproducer.hpp.

float StelToneReproducer::adaptLuminanceScaled ( float  worldLuminance) const
inline

Return adapted luminance from world to display with 1 corresponding to full display white.

Parameters
worldLuminancethe world luminance to convert in cd/m^2
Returns
the converted display luminance with 1 corresponding to full display white. The value can be more than 1 when saturation..

Definition at line 117 of file StelToneReproducer.hpp.

float StelToneReproducer::adaptLuminanceScaledLn ( float  lnWorldLuminance,
float  pFact = 0.5f 
) const
inline

Return adapted ln(luminance) from world to display with 1 corresponding to full display white.

Parameters
lnWorldLuminancethe world luminance to convert in ln(cd/m^2)
pFactthe power at whihc the result should be set. The default is 0.5 and therefore return the square root of the adapted luminance
Returns
the converted display set at the pFact power. Luminance with 1 corresponding to full display white. The value can be more than 1 when saturation..

Definition at line 134 of file StelToneReproducer.hpp.

float StelToneReproducer::getDisplayGamma ( ) const
inline

Get the display gamma.

Returns
the display gamma. Default value is 2.2222 for a CRT

Definition at line 91 of file StelToneReproducer.hpp.

float StelToneReproducer::getInputScale ( ) const
inline

Get the global scale applied to input lumiances, i.e before the adaptation.

Definition at line 81 of file StelToneReproducer.hpp.

float StelToneReproducer::getWorldAdaptationLuminance ( ) const
inline

Get the eye adaptation luminance for the world.

Definition at line 74 of file StelToneReproducer.hpp.

float StelToneReproducer::reverseAdaptLuminance ( float  displayLuminance) const
inline

Return adapted luminance from display to world.

Parameters
displayLuminancethe display luminance to convert in cd/m^2
Returns
the converted world luminance in cd/m^2

Definition at line 109 of file StelToneReproducer.hpp.

float StelToneReproducer::reverseAdaptLuminanceScaled ( float  displayLuminance) const
inline

Return adapted luminance from display to world with 1 corresponding to full display white.

Parameters
displayLuminancethe display luminance with 1 corresponding to full display white. The value can be more than 1 when saturation..
Returns
the converted world luminance in cd/m^2

Definition at line 125 of file StelToneReproducer.hpp.

void StelToneReproducer::setDisplayAdaptationLuminance ( float  displayAdaptationLuminance)

Set the eye adaptation luminance for the display (and precompute what can be) Usual luminance range is 1-100 cd/m^2 for a CRT screen.

Parameters
displayAdaptationLuminancethe new display luminance in cd/m^2. The initial default value is 50 cd/m^2
void StelToneReproducer::setDisplayGamma ( float  gamma)
inline

Set the display gamma.

Parameters
gammathe gamma. Initial default value is 2.2222

Definition at line 95 of file StelToneReproducer.hpp.

void StelToneReproducer::setInputScale ( float  scale = 1.f)

Set the global scale applied to input lumiances, i.e before the adaptation It is the parameter to modify to simulate aperture*exposition time.

Parameters
scalethe global input scale
void StelToneReproducer::setMaxDisplayLuminance ( float  maxdL)
inline

Set the maximum luminance of the display (CRT, screen etc..) This value is used to scale the RGB range.

Parameters
maxdLthe maximum lumiance in cd/m^2. Initial default value is 120 cd/m^2

Definition at line 86 of file StelToneReproducer.hpp.

void StelToneReproducer::setWorldAdaptationLuminance ( float  worldAdaptationLuminance)

Set the eye adaptation luminance for the world (and precompute what can be)

Parameters
worldAdaptationLuminancethe new world luminance in cd/m^2. The initial default value is 40000 cd/m^2 for Skylight Star Light : 0.001 cd/m^2 Moon Light : 0.1 cd/m^2 Indoor Lighting : 100 cd/m^2 Sun Light : 100000 cd/m^2
void StelToneReproducer::xyYToRGB ( float *  xyY) const

Convert from xyY color system to RGB.

The first two components x and y indicate the "color", the Y is luminance in cd/m^2.

Parameters
xyYan array of 3 floats which are replaced by the converted RGB values

The documentation for this class was generated from the following file: