Primitive for representation of CIE Lab color values. More...

#include <CLab.h>

Inheritance diagram for icmm::CLab:

Public Types
enum	ComponentIndex { CI_L , CI_A , CI_B }

typedef TComposedColor< 3 >	BaseClass

Public Types inherited from icmm::TComposedColor< 3 >
typedef imath::TVector< Size >	BaseClass

typedef BaseClass::Elements	Elements

Public Types inherited from imath::TVector< Size, Element >
typedef Element	ElementType

typedef Element	Elements[Size]

Public Types inherited from istd::IChangeable
enum	ChangeFlags { CF_ACF_INTERNAL = 0 , CF_ALL_DATA , CF_ANY , CF_DESTROYING , CF_DELEGATED , CF_NO_UNDO }
	Data model change notification flags. More...

enum	SupportedOperations { SO_NONE = 0 , SO_OBSERVE = 1 << 0 , SO_COPY = 1 << 1 , SO_CLONE = 1 << 2 , SO_COMPARE = 1 << 3 , SO_RESET = 1 << 4 }
	Flags for supported operations. More...

enum	CompatibilityMode { CM_STRICT , CM_WITHOUT_REFS , CM_WITH_REFS , CM_CONVERT }
	Control how relationship betweeen objects are interpreted. More...

typedef QMultiMap< QByteArray, QVariant >	ChangeInfoMap

Public Member Functions
	CLab (double l=0.0, double a=0.0, double b=0.0)

	CLab (const CLab &color)

double	GetL () const

void	SetL (double value)

double	GetA () const

void	SetA (double value)

double	GetB () const

void	SetB (double value)

virtual bool	Serialize (iser::IArchive &archive) override
	Load or store state of this object as a archive stream.

double	GetDeltaE (const CLab &lab) const

CLab	operator+ (const CLab &color) const

CLab	operator- (const CLab &color) const

CLab	operator* (const CLab &color) const

CLab	operator/ (const CLab &color) const

CLab	operator* (double value) const

CLab	operator/ (double value) const

CLab &	operator= (const CLab &color)

const CLab &	operator+= (const CLab &color)

const CLab &	operator-= (const CLab &color)

const CLab &	operator*= (const CLab &color)

const CLab &	operator/= (const CLab &color)

const CLab &	operator*= (double value)

const CLab &	operator/= (double value)

Public Member Functions inherited from icmm::TComposedColor< 3 >
	TComposedColor ()

	TComposedColor (const BaseClass &value)

	TComposedColor (const imath::CVarVector &vector)

	TComposedColor (const TComposedColor< Size > &color)=default

void	GetRounded (const imath::IDoubleManip &manipulator, TComposedColor< Size > &result)
	Get color after components value rounding with specified precision.

bool	IsRoundedEqual (const TComposedColor< Size > &color, const imath::IDoubleManip &manipulator) const
	Check if two values are equal after rounding.

bool	IsSimilar (const TComposedColor< Size > &color, double tolerance=I_BIG_EPSILON) const
	Allows to compare two colors with tolerance.

bool	IsNormalized () const
	Check if this color value is normalized.

void	Normalize ()
	Make this color to be normalized.

void	GetNormalized (TComposedColor< Size > &result) const
	Get normalized color.

TComposedColor< Size >	operator+ (const TComposedColor< Size > &color) const

TComposedColor< Size >	operator- (const TComposedColor< Size > &color) const

TComposedColor< Size >	operator* (const TComposedColor< Size > &color) const

TComposedColor< Size >	operator* (double value) const

TComposedColor< Size >	operator/ (const TComposedColor< Size > &color) const

TComposedColor< Size >	operator/ (double value) const

const TComposedColor< Size > &	operator= (const TComposedColor< Size > &color)

const TComposedColor< Size > &	operator= (double colorValue)

const TComposedColor< Size > &	operator+= (const TComposedColor< Size > &color)

const TComposedColor< Size > &	operator-= (const TComposedColor< Size > &color)

const TComposedColor< Size > &	operator*= (const TComposedColor< Size > &color)

const TComposedColor< Size > &	operator*= (double value)

const TComposedColor< Size > &	operator/= (const TComposedColor< Size > &color)

const TComposedColor< Size > &	operator/= (double value)

Public Member Functions inherited from imath::TVector< Size, Element >
	TVector ()
	Creates an uninitialized vector.

	TVector (const TVector< Size, Element > &vector)
	Creates a copy of another vector.

	TVector (std::initializer_list< Element > values)
	Creates a vector from an initializer list.

const Element &	GetElement (int i) const
	Gets the element at the specified index (read-only).

Element &	GetElementRef (int i)
	Gets a reference to the element at the specified index (read-write).

void	SetElement (int i, const Element &value)
	Sets the element at the specified index.

void	SetAllElements (const Element &value)
	Sets all elements to the same value.

void	Reset ()
	Sets all coordinates to zero.

void	Clear ()
	Sets all coordinates to zero.

const TVector< Size, Element >::Elements &	GetElements () const
	Get read-only access to internal element container.

TVector< Size, Element >::Elements &	GetElementsRef ()
	Get access to internal element container.

void	Translate (const TVector< Size, Element > &vector)
	Translates (adds) another vector to this vector.

TVector< Size, Element >	GetTranslated (const TVector< Size, Element > &vector)
	Returns a new vector that is the translation of this vector.

void	GetTranslated (const TVector< Size, Element > &vector, TVector< Size, Element > &result)
	Computes the translated vector and stores it in the result parameter.

void	ScaledCumulate (const TVector< Size, Element > &vector, Element scale)
	Adds a scaled vector to this vector.

bool	IsNull (Element tolerance=I_BIG_EPSILON) const
	Checks if this vector is null (all elements approximately zero).

Element	GetDotProduct (const TVector< Size, Element > &vector) const
	Calculates the dot product with another vector.

Element	GetLength2 () const
	Calculates the squared Euclidean length of the vector.

Element	GetLength () const
	Calculates the Euclidean length (magnitude) of the vector.

Element	GetDistance2 (const TVector< Size, Element > &vector) const
	Calculates the squared distance to another vector.

Element	GetDistance (const TVector< Size, Element > &vector) const
	Calculates the Euclidean distance to another vector.

Element	GetElementsSum () const
	Calculates the sum of all vector elements.

bool	Normalize (Element length=1.0)
	Normalizes the vector to a specified length.

bool	GetNormalized (TVector< Size, Element > &result, Element length=1.0) const
	Returns a normalized copy of this vector with specified length.

void	GetMinimal (const TVector< Size, Element > &vector, TVector< Size, Element > &result) const
	Get vector with minimal elements values.

void	GetMaximal (const TVector< Size, Element > &vector, TVector< Size, Element > &result) const
	Get vector with maximal elements values.

bool	Serialize (iser::IArchive &archive)
	Serialize this vector to specified archive.

bool	operator== (const TVector< Size, Element > &vector) const

bool	operator!= (const TVector< Size, Element > &vector) const

bool	operator< (const TVector< Size, Element > &vector) const

bool	operator> (const TVector< Size, Element > &vector) const

bool	operator<= (const TVector< Size, Element > &vector) const

bool	operator>= (const TVector< Size, Element > &vector) const

TVector< Size, Element > &	operator= (const TVector< Size, Element > &vector)=default

TVector< Size, Element >	operator- () const

TVector< Size, Element >	operator+ (const TVector< Size, Element > &vector) const

TVector< Size, Element >	operator- (const TVector< Size, Element > &vector) const

TVector< Size, Element >	operator* (Element scalar) const

TVector< Size, Element >	operator/ (Element scalar) const

TVector< Size, Element > &	operator+= (const TVector< Size, Element > &vector)

TVector< Size, Element > &	operator-= (const TVector< Size, Element > &vector)

TVector< Size, Element > &	operator*= (Element scalar)

TVector< Size, Element > &	operator/= (Element scalar)

const Element &	operator[] (int i) const

Element &	operator[] (int i)

Public Member Functions inherited from iser::ISerializable
virtual quint32	GetMinimalVersion (int versionId) const
	Get minimal needed version to correct storing of this data.

Public Member Functions inherited from istd::IChangeable
virtual int	GetSupportedOperations () const
	Get set of flags for supported operations.

virtual bool	CopyFrom (const IChangeable &object, CompatibilityMode mode=CM_WITHOUT_REFS)
	Copy this object from another one.

virtual bool	IsEqual (const IChangeable &object) const
	Compare this object with another object.

virtual istd::TUniqueInterfacePtr< istd::IChangeable >	CloneMe (CompatibilityMode mode=CM_WITHOUT_REFS) const
	Make a copy of this object.

virtual bool	ResetData (CompatibilityMode mode=CM_WITHOUT_REFS)
	Reset data to its default state.

virtual void	BeginChanges (const ChangeSet &changeSet)
	Starts the change transaction.

virtual void	EndChanges (const ChangeSet &changeSet)
	Ends the change transaction.

virtual void	BeginChangeGroup (const ChangeSet &changeSet)
	Starts group of changes.

virtual void	EndChangeGroup (const ChangeSet &changeSet)
	Ends group of changes.

Public Member Functions inherited from istd::IPolymorphic
virtual	~IPolymorphic ()

Additional Inherited Members
Static Public Member Functions inherited from imath::TVector< Size, Element >
static int	GetElementsCount ()
	Get number of elements.

static bool	SetElementsCount (int count)
	Set number of elements.

static const TVector< Size, Element > &	GetZero ()
	Get vector with all coordinates set to 0.

Static Public Member Functions inherited from istd::IChangeable
static const ChangeSet &	GetNoChanges ()
	Get empty set of changes.

static const ChangeSet &	GetAnyChange ()
	Get anonymous change set.

static const ChangeSet &	GetAllChanges ()
	Get anonymous change set.

static const ChangeSet &	GetDelegatedChanges ()
	Get delegated change set.

Protected Member Functions inherited from istd::IChangeable
virtual void	OnBeginChanges ()
	Callback function for begin change event.

virtual void	OnEndChanges (const ChangeSet &changeSet)
	Callback function for end change event.

Protected Attributes inherited from imath::TVector< Size, Element >
Elements	m_elements

Detailed Description

Primitive for representation of CIE Lab color values.

Purpose

CLab represents colors in the CIE L*a*b* color space, a device-independent, perceptually uniform color model designed to approximate human vision. Unlike RGB or CMYK, Lab is designed so that the numerical difference between two colors corresponds to the perceptual difference seen by humans. This makes it ideal for color comparison, color correction, and gamut mapping.

CIE Lab Color Space

Lab consists of three coordinates:

**L*** (Lightness): 0 (black) to 100 (white)
**a***: Green (-128) to Red (+127)
**b***: Blue (-128) to Yellow (+127)

The a* and b* axes represent opponent color dimensions:

a* < 0: Green tones
a* > 0: Red/magenta tones
b* < 0: Blue tones
b* > 0: Yellow tones
a* = b* = 0: Neutral gray

Lab Advantages

Perceptual Uniformity:**

Equal distances in Lab space ~ equal perceived color differences
Makes it ideal for DeltaE (Delta E) color difference calculations

Device Independence:**
Not tied to any specific device (monitor, printer)
Provides absolute color definition

Gamut Mapping:**
Easy to determine if colors are out of gamut
Natural for color space conversions

Usage Examples

// Example 1: Creating Lab colors
icmm::CLab white(100.0, 0.0, 0.0);        // L=100, neutral
icmm::CLab black(0.0, 0.0, 0.0);          // L=0, neutral
icmm::CLab midGray(50.0, 0.0, 0.0);       // L=50, neutral
 
icmm::CLab red(53.0, 80.0, 67.0);         // Typical red
icmm::CLab green(88.0, -86.0, 83.0);      // Typical green
icmm::CLab blue(32.0, 79.0, -108.0);      // Typical blue
 
// Example 2: Component access
icmm::CLab color;
color.SetL(75.0);    // Lightness
color.SetA(25.0);    // Red direction
color.SetB(-30.0);   // Blue direction
 
double lightness = color.GetL();
double a = color.GetA();
double b = color.GetB();
 
// Example 3: Calculating color difference (DeltaE)
double CompareColors(const icmm::CLab& color1, const icmm::CLab& color2)
{
       // DeltaE76 formula (CIE 1976)
       double deltaE = color1.GetDeltaE(color2);
       
       // Interpretation of DeltaE:
       // < 1.0: Imperceptible difference
       // 1-2: Perceptible by close observation
       // 2-10: Perceptible at a glance
       // 11-49: Colors are more similar than opposite
       // 100: Colors are exact opposites
       
       return deltaE;
}
 
icmm::CLab lab1(50.0, 10.0, 20.0);
icmm::CLab lab2(52.0, 12.0, 18.0);
double difference = CompareColors(lab1, lab2);  // Small difference
 
// Example 4: Finding closest color in palette
icmm::CLab FindClosestColor(const icmm::CLab& target,
                            const QList<icmm::CLab>& palette)
{
       if (palette.isEmpty()) return icmm::CLab();
       
       icmm::CLab closest = palette[0];
       double minDeltaE = target.GetDeltaE(closest);
       
       for (const icmm::CLab& color : palette) {
              double deltaE = target.GetDeltaE(color);
              if (deltaE < minDeltaE) {
                     minDeltaE = deltaE;
                     closest = color;
              }
       }
       
       return closest;
}
 
// Example 5: Adjusting lightness
icmm::CLab AdjustLightness(const icmm::CLab& color, double factor)
{
       icmm::CLab result = color;
       double newL = color.GetL() * factor;
       result.SetL(qBound(0.0, newL, 100.0));  // Clamp to valid range
       return result;
}
 
icmm::CLab dark = AdjustLightness(original, 0.7);    // Darker
icmm::CLab light = AdjustLightness(original, 1.3);   // Lighter
 
// Example 6: Checking if color is neutral (gray)
bool IsNeutral(const icmm::CLab& color, double tolerance = 5.0)
{
       // Neutral colors have a* and b* near zero
       return (qAbs(color.GetA()) < tolerance && 
               qAbs(color.GetB()) < tolerance);
}
 
// Example 7: Color quality control
struct ColorTolerance {
       double maxDeltaE;
       bool isAcceptable;
};
 
ColorTolerance CheckColorAccuracy(const icmm::CLab& reference,
                                  const icmm::CLab& sample,
                                  double tolerance = 2.0)
{
       ColorTolerance result;
       result.maxDeltaE = reference.GetDeltaE(sample);
       result.isAcceptable = (result.maxDeltaE <= tolerance);
       return result;
}
 
// Example 8: Gamut mapping - checking if color is displayable
bool IsInSRgbGamut(const icmm::CLab& labColor)
{
       // Convert to RGB (via transformation)
       // Check if RGB components are in [0, 1]
       // This is simplified - actual implementation uses transformations
       icmm::CRgb rgb = ConvertLabToRgb(labColor);
       
       return (rgb.GetRed() >= 0.0 && rgb.GetRed() <= 1.0 &&
               rgb.GetGreen() >= 0.0 && rgb.GetGreen() <= 1.0 &&
               rgb.GetBlue() >= 0.0 && rgb.GetBlue() <= 1.0);
}
 
// Example 9: Perceptual color blending
icmm::CLab BlendLabColors(const icmm::CLab& a,
                          const icmm::CLab& b,
                          double t)  // 0 to 1
{
       // Linear interpolation in Lab space gives perceptual blending
       return icmm::CLab(
              a.GetL() * (1.0 - t) + b.GetL() * t,
              a.GetA() * (1.0 - t) + b.GetA() * t,
              a.GetB() * (1.0 - t) + b.GetB() * t
       );
}

Delta E (DeltaE) Color Difference

The DeltaE value quantifies the perceptual difference between two colors:

DeltaE76 (CIE 1976):**

DeltaE = sqrt((L1-L2)^2 + (a1-a2)^2 + (b1-b2)^2)
Simple Euclidean distance in Lab space
Available via GetDeltaE() method

Interpretation:**
0-1: Not perceptible by human eye
1-2: Perceptible through close observation
2-10: Perceptible at a glance
10-50: Colors are more similar than opposite
**>50**: Colors are significantly different

Common Applications

Color Quality Control: Compare production colors to standards
Color Matching: Find closest colors in a palette
Gamut Mapping: Convert between color spaces while preserving appearance
Color Correction: Adjust colors perceptually
Image Analysis: Segment images by perceptual color
Fashion/Design: Specify colors independently of device

Best Practices

Use Lab for perceptual color operations (blending, matching)
Use Lab for color difference calculations (quality control)
Convert to Lab from any color space via XYZ as intermediate
Be aware of illuminant - Lab is relative to a white point (usually D65)
Use DeltaE for objective color difference measurements
Consider DeltaE2000 for more accurate perceptual differences (not in this class)
Lab values are typically normalized to [0,1] range in ACF but represent actual Lab ranges

Note: In ACF, component values are normalized to [0, 1] range internally, but represent the actual Lab ranges (L: 0-100, a: -128 to +127, b: -128 to +127)

See also: icmm::TComposedColor, icmm::CCieLabColorModel, icmm::CXyzToCieLabTransformation, icmm::CCieLabColor

Definition at line 214 of file CLab.h.

Member Typedef Documentation

◆ BaseClass

typedef TComposedColor<3> icmm::CLab::BaseClass

Definition at line 217 of file CLab.h.

Member Enumeration Documentation

◆ ComponentIndex

enum icmm::CLab::ComponentIndex

Enumerator
CI_L
CI_A
CI_B

Definition at line 219 of file CLab.h.

Constructor & Destructor Documentation

◆ CLab() [1/2]

icmm::CLab::CLab	(	double	l = `0.0`,
		double	a = `0.0`,
		double	b = `0.0`
	)

inline

Definition at line 264 of file CLab.h.

References CI_A, CI_B, CI_L, and imath::TVector< Size, Element >::SetElement().

◆ CLab() [2/2]

icmm::CLab::CLab ( const CLab & color )

inline

Definition at line 272 of file CLab.h.

Member Function Documentation

◆ GetA()

double icmm::CLab::GetA ( ) const

inline

Definition at line 292 of file CLab.h.

References CI_A, and imath::TVector< Size, Element >::GetElement().

◆ GetB()

double icmm::CLab::GetB ( ) const

inline

Definition at line 304 of file CLab.h.

References CI_B, and imath::TVector< Size, Element >::GetElement().

◆ GetDeltaE()

double icmm::CLab::GetDeltaE ( const CLab & lab ) const

◆ GetL()

double icmm::CLab::GetL ( ) const

inline

Definition at line 280 of file CLab.h.

References CI_L, and imath::TVector< Size, Element >::GetElement().

◆ operator*() [1/2]

CLab icmm::CLab::operator* ( const CLab & color ) const

inline

Definition at line 338 of file CLab.h.

◆ operator*() [2/2]

CLab icmm::CLab::operator* ( double value ) const

inline

Definition at line 358 of file CLab.h.

◆ operator*=() [1/2]

const CLab & icmm::CLab::operator*= ( const CLab & color )

inline

Definition at line 402 of file CLab.h.

References icmm::TComposedColor< 3 >::operator*=().

◆ operator*=() [2/2]

const CLab & icmm::CLab::operator*= ( double value )

inline

Definition at line 418 of file CLab.h.

References icmm::TComposedColor< 3 >::operator*=().

◆ operator+()

CLab icmm::CLab::operator+ ( const CLab & color ) const

inline

Definition at line 318 of file CLab.h.

◆ operator+=()

const CLab & icmm::CLab::operator+= ( const CLab & color )

inline

Definition at line 386 of file CLab.h.

References icmm::TComposedColor< 3 >::operator+=().

◆ operator-()

CLab icmm::CLab::operator- ( const CLab & color ) const

inline

Definition at line 328 of file CLab.h.

◆ operator-=()

const CLab & icmm::CLab::operator-= ( const CLab & color )

inline

Definition at line 394 of file CLab.h.

References icmm::TComposedColor< 3 >::operator-=().

◆ operator/() [1/2]

CLab icmm::CLab::operator/ ( const CLab & color ) const

inline

Definition at line 348 of file CLab.h.

◆ operator/() [2/2]

CLab icmm::CLab::operator/ ( double value ) const

inline

Definition at line 368 of file CLab.h.

◆ operator/=() [1/2]

const CLab & icmm::CLab::operator/= ( const CLab & color )

inline

Definition at line 410 of file CLab.h.

References icmm::TComposedColor< 3 >::operator/=().

◆ operator/=() [2/2]

const CLab & icmm::CLab::operator/= ( double value )

inline

Definition at line 426 of file CLab.h.

References icmm::TComposedColor< 3 >::operator/=().

◆ operator=()

CLab & icmm::CLab::operator= ( const CLab & color )

inline

Definition at line 378 of file CLab.h.

References icmm::TComposedColor< 3 >::operator=().

◆ Serialize()

virtual bool icmm::CLab::Serialize ( iser::IArchive & archive )

overridevirtual

Load or store state of this object as a archive stream.

Type of operation is depending on archive type.

See also: iser::IArchive

Reimplemented from icmm::TComposedColor< 3 >.

◆ SetA()

void icmm::CLab::SetA ( double value )

inline

Definition at line 298 of file CLab.h.

References CI_A, and imath::TVector< Size, Element >::SetElement().

◆ SetB()

void icmm::CLab::SetB ( double value )

inline

Definition at line 310 of file CLab.h.

References CI_B, and imath::TVector< Size, Element >::SetElement().

◆ SetL()

void icmm::CLab::SetL ( double value )

inline

Definition at line 286 of file CLab.h.

References CI_L, and imath::TVector< Size, Element >::SetElement().

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

Acf/Include/icmm/CLab.h

Public Types

Public Member Functions

Additional Inherited Members

Detailed Description

Purpose

CIE Lab Color Space

Lab Advantages

Usage Examples

Delta E (DeltaE) Color Difference

Common Applications

Best Practices

Member Typedef Documentation

◆ BaseClass

Member Enumeration Documentation

◆ ComponentIndex

Constructor & Destructor Documentation

◆ CLab() [1/2]

◆ CLab() [2/2]

Member Function Documentation

◆ GetA()

◆ GetB()

◆ GetDeltaE()

◆ GetL()

◆ operator*() [1/2]

◆ operator*() [2/2]

◆ operator*=() [1/2]

◆ operator*=() [2/2]

◆ operator+()

◆ operator+=()

◆ operator-()

◆ operator-=()

◆ operator/() [1/2]

◆ operator/() [2/2]

◆ operator/=() [1/2]

◆ operator/=() [2/2]

◆ operator=()

◆ Serialize()

◆ SetA()

◆ SetB()

◆ SetL()