Magick::Color

Color is the base color class in Magick++. It is a simple container class for the pixel red, green, blue, and alpha values scaled to fit ImageMagick's Quantum size. Normally users will instantiate a class derived from Color which supports the color model that fits the needs of the application. The Color class may be constructed directly from an X11-style color string.

Available derived color specification classes are shown in the following table:

Color Derived Classes

ImageMagick may be compiled to support 32 or 64 bit pixels of type PixelPacket. This is controlled by the value of the QuantumDepth define. The default is 64 bit pixels, which provides the best accuracy. If memory consumption and/or processing time must be minimized, then ImageMagick may be compiled with QuantumDepth=8. The following table shows the relationship between QuantumDepth, the type of Quantum, and the overall PixelPacket size.

Effect Of QuantumDepth Values

Color Class

The Color base class is not intended to be used directly. Normally a user will construct a derived class or inherit from this class. Color arguments are must be scaled to fit the Quantum size. The Color class contains a pointer to a PixelPacket, which may be allocated by the Color class, or may refer to an existing pixel in an image.

An alternate way to construct the class is via an X11-compatible color specification string.

class Color
{
  public:
    Color ( Quantum red_,
     Quantum green_,
     Quantum blue_ );
    Color ( Quantum red_,
     Quantum green_,
     Quantum blue_,
     Quantum alpha_ );
    Color ( const std::string &x11color_ );
    Color ( const char * x11color_ );
    Color ( void );
    virtual        ~Color ( void );
    Color ( const Color & color_ );

    // Red color (range 0 to MaxRGB)
    void           redQuantum ( Quantum red_ );
    Quantum        redQuantum ( void ) const;

    // Green color (range 0 to MaxRGB)
    void           greenQuantum ( Quantum green_ );
    Quantum        greenQuantum ( void ) const;

    // Blue color (range 0 to MaxRGB)
    void           blueQuantum ( Quantum blue_ );
    Quantum        blueQuantum ( void ) const;

    // Alpha level (range OpaqueOpacity=0 to TransparentOpacity=MaxRGB)
    void           alphaQuantum ( Quantum alpha_ );
    Quantum        alphaQuantum ( void ) const;

    // Scaled (to 1.0) version of alpha for use in sub-classes
    // (range opaque=0 to transparent=1.0)
    void           alpha ( double alpha_ );
    double         alpha ( void ) const;
 
    // Does object contain valid color?
    void           isValid ( bool valid_ );
    bool           isValid ( void ) const;
 
    // Set color via X11 color specification string
    const Color& operator= ( const std::string &x11color_ );
    const Color& operator= ( const char * x11color_ );

    // Assignment operator
    Color& operator= ( const Color& color_ );
 
    // Return X11 color specification string
    /* virtual */ operator std::string() const;

    // Return ImageMagick PixelPacket
    operator PixelPacket() const;

    // Construct color via ImageMagick PixelPacket
    Color ( const PixelPacket &color_ );

    // Set color via ImageMagick PixelPacket
    const Color& operator= ( PixelPacket &color_ );
};
 

ColorRGB

Representation of an RGB color. All color arguments have a valid range of 0.0 - 1.0.

class ColorRGB : public Color
{
  public:
    ColorRGB ( double red_, double green_, double blue_ );
    ColorRGB ( void );
    ColorRGB ( const Color & color_ );
    /* virtual */  ~ColorRGB ( void );
 
    void           red ( double red_ );
    double         red ( void ) const;
 
    void           green ( double green_ );
    double         green ( void ) const;
 
    void           blue ( double blue_ );
    double         blue ( void ) const;

    // Assignment operator from base class
    ColorRGB& operator= ( const Color& color_ );
};
 

ColorGray

Representation of a grayscale color (in RGB colorspace). Grayscale is simply RGB with equal parts of red, green, and blue. All double arguments have a valid range of 0.0 - 1.0.

class ColorGray : public Color
{
  public:
    ColorGray ( double shade_ );
    ColorGray ( void );
    ColorGray ( const Color & color_ );
    /* virtual */ ~ColorGray ();

    void           shade ( double shade_ );
    double         shade ( void ) const;

    // Assignment operator from base class
    ColorGray& operator= ( const Color& color_ );
};
 

ColorMono

Representation of a black/white pixel (in RGB colorspace). Color arguments are constrained to 'false' (black pixel) and 'true' (white pixel).

class ColorMono : public Color
{
  public:
    ColorMono ( bool mono_ );
    ColorMono ( void );
    ColorMono ( const Color & color_ );
    /* virtual */ ~ColorMono ();
 
    void           mono ( bool mono_ );
    bool           mono ( void ) const;

    // Assignment operator from base class
    ColorMono& operator= ( const Color& color_ );
};
 

ColorHSL

Representation of a color in Hue/Saturation/Luminosity (HSL) colorspace.

class ColorHSL : public Color
{
  public:
    ColorHSL ( double hue_, double saturation_, double luminosity_ );
    ColorHSL ( void );
    ColorHSL ( const Color & color_ );
    /* virtual */  ~ColorHSL ( );
 
    void           hue ( double hue_ );
    double         hue ( void ) const;
 
    void           saturation ( double saturation_ );
    double         saturation ( void ) const;
 
    void           luminosity ( double luminosity_ );
    double         luminosity ( void ) const;

    // Assignment operator from base class
    ColorHSL& operator= ( const Color& color_ );
};
 

ColorYUV

Representation of a color in YUV colorspace (used to encode color for television transmission).

 Argument ranges:
        Y:  0.0 through 1.0
        U: -0.5 through 0.5
        V: -0.5 through 0.5

class ColorYUV : public Color
{
  public:
    ColorYUV ( double y_, double u_, double v_ );
    ColorYUV ( void );
    ColorYUV ( const Color & color_ );
    /* virtual */ ~ColorYUV ( void );
 
    void           u ( double u_ );
    double         u ( void ) const;
 
    void           v ( double v_ );
    double         v ( void ) const;
 
    void           y ( double y_ );
    double         y ( void ) const;

    // Assignment operator from base class
    ColorYUV& operator= ( const Color& color_ );
};