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@@ -3,7 +3,252 @@ NAME
DESCRIPTION
libcolour is C library for colour space conversions.
+ libcolour provides conversion between a large number of colour
+ spaces, including many different RGB colour spaces. It also
+ supports encode and non-encoded representations. libcolour
+ futhermore provides access to custom RGB colour spaces.
-SEE ALSO
- libclut(7)
+ To use libcolour, include the header file <libcolour.h> and
+ link with /usr/local/lib/libcolour.a -lm or -lcolour.
+COLOUR MODELS
+ libcolour supports a number of colour models. A colour model
+ is specified with a value of
+
+ typedef enum libcolour_model libcolour_model_t;
+
+ The colour models can listed using the macros
+
+ LIBCOLOUR_LIST_MODELS(IMACRO, TYPE_AFFIX)
+
+ or
+
+ LIBCOLOUR_LIST_MODELS_N(MACRO, TYPE_AFFIX, ...)
+
+ where MACRO is the macro that shall be expanded, and
+ TYPE_AFFIX shall be f, lf, or llf for float-typed,
+ double-typed, and long double-typed colour module stuctures,
+ respectively. LIBCOLOUR_LIST_MODELS expands MACRO with three
+ parameters: enum libcolour_model value of the colour model,
+ typedef-name of struct used to store colours of the colour
+ model, and the name of the member in union libcolour_colour_f,
+ union libcolour_colour_lf, and union libcolour_colour_llf that
+ is used to store a colour with the colour model.
+ LIBCOLOUR_LIST_MODELS_N is identical to LIBCOLOUR_LIST_MODELS
+ except allows the programmer to specify additional parameters
+ to pass MACRO when it is expanded.
+
+ There there are three structs defined for each colour model,
+ the first member in each struct is
+
+ enum libcolour_model model;
+
+ The three structs for each colour model are for different data
+ types: float, double, and long double. For example, for sRGB,
+ the follow structs are defined:
+
+ typedef struct libcolour_srgb_f libcolour_srgb_f_t;
+ typedef struct libcolour_srgb_lf libcolour_srgb_lf_t;
+ typedef struct libcolour_srgb_llf libcolour_srgb_llf_t;
+
+ for float, double, and long double, respectively. Similarly,
+
+ typedef union libcolour_colour_f libcolour_colour_f_t;
+ typedef union libcolour_colour_lf libcolour_colour_lf_t;
+ typedef union libcolour_colour_llf libcolour_colour_llf_t;
+
+ are used for float, double, long double, respectively, and all
+ have the member
+
+ enum libcolour_model model;
+
+ The structs are not padded to be of the same size.
+
+ <libcolour.h> defines structs the following for colour models:
+
+ Generic RGB
+ See LIBCOLOUR_RGB(7).
+
+ Standard RGB
+ See LIBCOLOUR_SRGB(7).
+
+ CIE xyY
+ See LIBCOLOUR_CIEXYY(7).
+
+ CIE 1931 XYZ
+ See LIBCOLOUR_CIEXYZ(7).
+
+ CIE L*a*b*
+ See LIBCOLOUR_CIELAB(7).
+
+ CIE 1976 (L*, u*, v*)
+ See LIBCOLOUR_CIELUV(7).
+
+ CIE LChuv (also known as CIE HLCuv)
+ See LIBCOLOUR_CIELCHUV(7).
+
+ YIQ
+ See LIBCOLOUR_YIQ(7).
+
+ YDbDr
+ See LIBCOLOUR_YDBDR(7).
+
+ YUV
+ See LIBCOLOUR_YUV(7).
+
+ YPBPR
+ See LIBCOLOUR_YPBPR(7).
+
+ YCgCo
+ See LIBCOLOUR_YCGCO(7).
+
+ CIE 1960 UCS
+ See LIBCOLOUR_CIE1960UCS(7).
+
+ CIE 1964 (U*, V*, W*)
+ See LIBCOLOUR_CIEUVW(7).
+
+ILLUMINANTS
+ libcolour provides a number of initialiser macros for standard
+ illuminants. The following macros expand to a
+ libcolour_ciexyy_f_t with the standard 2 degrees observer
+ value in CIE xyY, each have a supplementary 10 degrees
+ observer counterpart using suffix _10DEG_OBS, both with the Y
+ value set to 1. Additionally, each macro, including the
+ _10DEG_OBS variants, have a variant that uses the _LF affix
+ that expands to a libcolour_ciexyy_lf_t and a variant that
+ uses the _LLF affix that expands to a libcolour_ciexyy_llf_t
+ in addition to the listed variants that uses the _F affix.
+
+ LIBCOLOUR_ILLUMINANT_A_F
+ CIE Standard Illuminant A.
+ Incandescent/Tungsten.
+ 2855.54K (2848K in old definition of 1K).
+
+ LIBCOLOUR_ILLUMINANT_B_F
+ CIE Standard Illuminant B.
+ Direct sunlight at noon (obsolete).
+ 4874K.
+
+ LIBCOLOUR_ILLUMINANT_C_F
+ CIE Standard Illuminant C.
+ Average/north sky daylight (obsolete).
+ 6774K.
+
+ LIBCOLOUR_ILLUMINANT_D50_F
+ CIE Standard Illuminant D50.
+ Horizon Light.
+ 5002.78K (5000K in old definition of 1K).
+
+ LIBCOLOUR_ILLUMINANT_D55_F
+ CIE Standard Illuminant D55.
+ Mid-morning/mid-afternoon daylight.
+ 5503.06K (5500K in old definition of 1K).
+
+ LIBCOLOUR_ILLUMINANT_D65_F
+ CIE Standard Illuminant D65.
+ Noon daylight.
+ 6503.62K (6500K in old definition of 1K).
+
+ LIBCOLOUR_ILLUMINANT_D75_F
+ CIE Standard Illuminant D75.
+ North sky daylight.
+ 7504.17K (7500K in old definition of 1K).
+
+ LIBCOLOUR_ILLUMINANT_E_F
+ CIE Standard Illuminant E.
+ Equal energy.
+ 5454K.
+
+ LIBCOLOUR_ILLUMINANT_F1_F
+ CIE Standard Illuminant F1.
+ Daylight fluorescent.
+ 6430K.
+
+ LIBCOLOUR_ILLUMINANT_F2_F
+ CIE Standard Illuminant F2.
+ Cool white fluorescent.
+ 4230K.
+
+ LIBCOLOUR_ILLUMINANT_F3_F
+ CIE Standard Illuminant F3.
+ White fluorescent.
+ 3450K.
+
+ LIBCOLOUR_ILLUMINANT_F4_F
+ CIE Standard Illuminant F4.
+ Warm white fluorescent.
+ 2940K.
+
+ LIBCOLOUR_ILLUMINANT_F5_F
+ CIE Standard Illuminant F5.
+ Daylight fluorescent.
+ 6350K.
+
+ LIBCOLOUR_ILLUMINANT_F6_F
+ CIE Standard Illuminant F6.
+ Lite white fluorescent.
+ 4150K.
+
+ LIBCOLOUR_ILLUMINANT_F7_F
+ CIE Standard Illuminant F7.
+ D65 simulator, daylight simulator.
+ 6500K.
+
+ LIBCOLOUR_ILLUMINANT_F8_F
+ CIE Standard Illuminant F8.
+ D50 simulator, Sylvania F40 Design 50.
+ 5000K.
+
+ LIBCOLOUR_ILLUMINANT_F9_F
+ CIE Standard Illuminant F9.
+ Cool white deluxe fluorescent.
+ 4150K.
+
+ LIBCOLOUR_ILLUMINANT_F10_F
+ CIE Standard Illuminant F10.
+ Philips TL85, Ultralume 50.
+ 5000K.
+
+ LIBCOLOUR_ILLUMINANT_F11_F
+ CIE Standard Illuminant F11.
+ Philips TL84, Ultralume 40.
+ 4000K.
+
+ LIBCOLOUR_ILLUMINANT_F12_F
+ CIE Standard Illuminant F12.
+ Philips TL83, Ultralume 30.
+ 3000K.
+
+FUNCTIONS
+ libcolour_convert(3)
+ Colour space and colour model conversion.
+
+ libcolour_srgb_encode(3)
+ Apply the sRGB transfer function.
+
+ libcolour_srgb_decode(3)
+ Unapply the sRGB transfer function.
+
+ libcolour_delta_e(3)
+ Calculate delta E*_ab distance.
+
+ libcolour_proper(3)
+ Sets any member or submember that may be incorrectly
+ set.
+
+ libcolour_get_rgb_colour_space(3)
+ Selects RGB colour space.
+
+ libcolour_marshal(3)
+ Marshal a colour record.
+
+ libcolour_unmarshal(3)
+ Unmarshal a colour record.
+
+NOTES
+ All enum values have a macro with the same name defined which
+ can be used to test the existance of value.
+
+AUTHORS
+ Mattias Andrée <maandree@kth.se>