Feature Flags Reference #

Farg uses granular feature flags so you only compile what you need. This document lists every feature flag, what it provides, and any implicit dependencies.

Always Available #

The following are included with no feature flags enabled:

Item	Description
Xyz	CIE 1931 XYZ tristimulus color space
Lms	LMS cone response color space
Rgb<Srgb>	Standard RGB (IEC 61966-2-1)
Illuminant::D65	Noon daylight reference illuminant
Observer::CIE_1931_2D	CIE 1931 2° standard colorimetric observer
Xy chromaticity	CIE 1931 (x, y) chromaticity coordinates
XYZ Scaling CAT	Identity-matrix chromatic adaptation (scales X, Y, Z independently)

Default Features #

Enabled by default:

Feature	Provides
cat-bradford	Bradford chromatic adaptation transform
contrast-apca	APCA lightness contrast
contrast-wcag	WCAG 2.x contrast ratio
cvd-brettel	Brettel 1997 dichromacy simulation
cvd-machado	Machado 2009 anomalous trichromacy
distance-ciede2000	CIEDE2000 color difference

[dependencies]
farg = "0.4"

Meta-Features #

Group features that enable entire categories at once.

Feature	Enables
full	All categories below
all-cats	All 9 chromatic adaptation transforms
all-cct	All 4 correlated color temperature algorithms
all-chromaticity	All 3 chromaticity coordinate systems
all-contrast	All 6 contrast algorithms
all-cvd	All 3 color vision deficiency simulation algorithms
all-distance	All 6 color distance algorithms
all-illuminants	All illuminant sub-groups (standard, daylight, fluorescent, FL3, HP, LED)
all-observers	All 7 additional observers
all-rgb-spaces	All 37 additional RGB color spaces
all-spaces	All color spaces (CIE, cylindrical, perceptual, subtractive, and all RGB)

[dependencies]
farg = { version = "0.4", features = ["full"] }

Chromatic Adaptation Transforms #

Nine CATs available behind individual cat-* flags. XYZ Scaling is always available.

Feature	Transform	Description
cat-bradford	Bradford	Best general-purpose CAT (default)
cat-cat02	CAT02	From the CIECAM02 color appearance model
cat-cat16	CAT16	From the CAM16 color appearance model
cat-cmc-cat97	CMC CAT97	CMC CAT97 transform
cat-cmc-cat2000	CMC CAT2000	CMC CAT2000 transform
cat-fairchild	Fairchild	Fairchild transform
cat-hunt-pointer-estevez	Hunt-Pointer-Estevez	HPE cone-response transform
cat-sharp	Sharp	Sharp transform (Susstrunk et al.)
cat-von-kries	Von Kries	Diagonal adaptation with HPE-like cones

cat-hpe is an alias for cat-hunt-pointer-estevez.

Chromaticity Coordinate Systems #

Three additional chromaticity types. CIE 1931 (x, y) is always available.

Feature	Type	Description
chromaticity-rg	Rg	RGB-relative chromaticity (r, g)
chromaticity-upvp	Upvp	CIE 1976 UCS chromaticity (u', v')
chromaticity-uv	Uv	CIE 1960 UCS chromaticity (u, v)

Correlated Color Temperature #

Four CCT estimation algorithms available behind individual cct-* flags.

Feature	Algorithm	Description	Dependencies
cct-hernandez-andres	Hernandez-Andres	Higher-order polynomial (3,000–800,000 K)	-
cct-mccamy	McCamy	Third-degree polynomial (~2,000–12,500 K)	-
cct-ohno	Ohno	Planckian locus search with parabolic refinement	chromaticity-uv
cct-robertson	Robertson	Isotherm interpolation from 31-entry lookup table	chromaticity-uv

Contrast Algorithms #

Six contrast algorithms available behind individual contrast-* flags.

Feature	Algorithm	Description
contrast-aert	AERT	W3C AERT brightness difference (0-255)
contrast-apca	APCA	Accessible Perceptual Contrast Algorithm (Lc values)
contrast-michelson	Michelson	Visibility/modulation contrast (0.0-1.0)
contrast-rms	RMS	Root mean square luminance contrast
contrast-wcag	WCAG	WCAG 2.x contrast ratio (1:1 to 21:1)
contrast-weber	Weber	Weber contrast for target-on-background visibility

Color Vision Deficiency Simulation #

Three CVD simulation algorithms available behind individual cvd-* flags.

Feature	Algorithm	Description
cvd-brettel	Brettel	Half-plane dichromacy projection in LMS (most accurate)
cvd-machado	Machado	Severity-parameterized anomalous trichromacy in sRGB
cvd-vienot	Viénot	Single-matrix dichromacy projection in sRGB (faster)

Color Distance Algorithms #

Six color distance algorithms available behind individual distance-* flags.

Feature	Algorithm	Description	Dependencies
distance-ciede2000	CIEDE2000	Most perceptually uniform CIE metric (default)	space-lab
distance-cie76	CIE76	Euclidean distance in CIELAB space	space-lab
distance-cie94	CIE94	Weighted CIELAB difference (graphic arts / textiles)	space-lab
distance-ciecmc	CMC l:c	LCh-based difference for textile industry	space-lch
distance-euclidean	Euclidean	Straight-line distance in XYZ space	-
distance-manhattan	Manhattan	Taxicab distance in XYZ space	-

Illuminants #

44 illuminants across 6 sub-groups. D65 is always available.

Standard (illuminant-standard) #

Feature	Illuminant	Type	Description
illuminant-a	A	Incandescent	Tungsten lamp (2856 K)
illuminant-b	B	Daylight	Obsolete daylight simulator
illuminant-c	C	Daylight	Obsolete daylight simulator
illuminant-e	E	Equal energy	Equal-energy illuminant

Daylight (illuminant-daylight) #

Feature	Illuminant	Description
illuminant-d50	D50	Horizon daylight (5003 K)
illuminant-d55	D55	Mid-morning daylight (5503 K)
illuminant-d75	D75	North sky daylight (7504 K)
illuminant-id50	ID50	Indoor daylight D50
illuminant-id65	ID65	Indoor daylight D65

Fluorescent (illuminant-fluorescent) #

Feature	Illuminant	Description
illuminant-fl1	FL1	Daylight fluorescent (6430 K)
illuminant-fl2	FL2	Cool white fluorescent (4230 K)
illuminant-fl3	FL3	White fluorescent (3450 K)
illuminant-fl4	FL4	Warm white fluorescent (2940 K)
illuminant-fl5	FL5	Daylight fluorescent (6350 K)
illuminant-fl6	FL6	Lite white fluorescent (4150 K)
illuminant-fl7	FL7	Broadband daylight fluorescent
illuminant-fl8	FL8	Broadband cool white fluorescent
illuminant-fl9	FL9	Broadband warm white fluorescent
illuminant-fl10	FL10	Narrowband daylight fluorescent
illuminant-fl11	FL11	Narrowband cool white fluorescent
illuminant-fl12	FL12	Narrowband warm white fluorescent

Fluorescent Series 3 (illuminant-fluorescent-3) #

Feature	Illuminant	Description
illuminant-fl3-1	FL3.1	Halophosphate daylight (6430 K)
illuminant-fl3-2	FL3.2	Halophosphate cool white (4230 K)
illuminant-fl3-3	FL3.3	Halophosphate white (3450 K)
illuminant-fl3-4	FL3.4	Halophosphate warm white (2940 K)
illuminant-fl3-5	FL3.5	Three-band daylight (6350 K)
illuminant-fl3-6	FL3.6	Three-band cool white (4150 K)
illuminant-fl3-7	FL3.7	Broadband D65 simulator
illuminant-fl3-8	FL3.8	Broadband sRGB simulator
illuminant-fl3-9	FL3.9	Broadband warm white
illuminant-fl3-10	FL3.10	Three-band indoor daylight
illuminant-fl3-11	FL3.11	Three-band cool white indoor
illuminant-fl3-12	FL3.12	Three-band warm white indoor
illuminant-fl3-13	FL3.13	Narrowband daylight simulator
illuminant-fl3-14	FL3.14	Narrowband cool white simulator
illuminant-fl3-15	FL3.15	Narrowband white + red boost

High-Pressure Discharge (illuminant-hp) #

Feature	Illuminant	Description
illuminant-hp1	HP1	Sodium standard
illuminant-hp2	HP2	Sodium colour-enhanced
illuminant-hp3	HP3	Metal halide (high CRI)
illuminant-hp4	HP4	High-pressure mercury
illuminant-hp5	HP5	High-pressure mercury (high CRI)

LED (illuminant-led) #

Feature	Illuminant	Description
illuminant-led-b1	LED-B1	Blue phosphor LED (2733 K)
illuminant-led-b2	LED-B2	Blue phosphor LED (2998 K)
illuminant-led-b3	LED-B3	Blue phosphor LED (4103 K)
illuminant-led-b4	LED-B4	Blue phosphor LED (5109 K)
illuminant-led-b5	LED-B5	Blue phosphor LED (6598 K)
illuminant-led-bh1	LED-BH1	Blue-hybrid LED (2851 K)
illuminant-led-rgb1	LED-RGB1	RGB LED (2840 K)
illuminant-led-v1	LED-V1	Violet phosphor LED (2724 K)
illuminant-led-v2	LED-V2	Violet phosphor LED (4070 K)

Observers #

Seven additional observers. CIE 1931 2° is always available.

Feature	Observer	Description
observer-cie-1931-judd-2d	CIE 1931 Judd 2°	Judd-modified 1931 observer
observer-cie-1931-judd-vos-2d	CIE 1931 Judd-Vos 2°	Judd-Vos-modified 1931 observer
observer-cie-1964-10d	CIE 1964 10°	Supplementary standard observer
observer-cie-2006-2d	CIE 2006 2°	Physiologically-relevant (2°)
observer-cie-2006-10d	CIE 2006 10°	Physiologically-relevant (10°)
observer-stockman-sharpe-2d	Stockman-Sharpe 2°	Cone fundamentals (2°)
observer-stockman-sharpe-10d	Stockman-Sharpe 10°	Cone fundamentals (10°)

RGB Color Spaces #

37 additional RGB spaces. sRGB is always available.

Cinema and VFX #

Feature	Space	Illuminant	Description
rgb-aces-2065-1	ACES 2065-1	D60	ACES archival/interchange (AP0)
rgb-aces-cc	ACEScc	D60	ACES color correction
rgb-aces-cct	ACEScct	D60	ACES color correction with toe
rgb-aces-cg	ACEScg	D60	ACES CG working space (AP1)
rgb-arri-wide-gamut-3	ARRI Wide Gamut 3	D65	ARRI Alexa camera
rgb-arri-wide-gamut-4	ARRI Wide Gamut 4	D65	ARRI Alexa 35 camera
rgb-blackmagic-wide-gamut	Blackmagic Wide Gamut	D65	Blackmagic Design cameras
rgb-canon-cinema-gamut	Canon Cinema Gamut	D65	Canon Cinema EOS cameras
rgb-davinci-wide-gamut	DaVinci Wide Gamut	D65	DaVinci Resolve
rgb-filmlight-e-gamut	FilmLight E-Gamut	D65	FilmLight Baselight
rgb-panasonic-v-gamut	Panasonic V-Gamut	D65	Panasonic VariCam cameras
rgb-red-wide-gamut-rgb	RED Wide Gamut RGB	D65	RED cameras
rgb-sony-s-gamut-3	Sony S-Gamut3	D65	Sony cameras
rgb-sony-s-gamut-3-cine	Sony S-Gamut3.Cine	D65	Sony cameras (cinema)

Broadcast and Video #

Feature	Space	Illuminant	Description
rgb-rec-601	Rec. 601	D65	ITU-R BT.601 (SD video)
rgb-rec-709	Rec. 709	D65	ITU-R BT.709 (HD video)
rgb-rec-2020	Rec. 2020	D65	ITU-R BT.2020 (UHD video)
rgb-rec-2100-hlg	Rec. 2100 HLG	D65	BT.2100 with HLG transfer
rgb-rec-2100-pq	Rec. 2100 PQ	D65	BT.2100 with PQ transfer
rgb-ntsc	NTSC	C *	NTSC (1953) primaries
rgb-pal-secam	PAL/SECAM	D65	PAL/SECAM primaries
rgb-smpte-c	SMPTE-C	D65	SMPTE-C (NTSC successor)

Display #

Feature	Space	Illuminant	Description
rgb-display-p3	Display P3	D65	Apple Display P3
rgb-dci-p3	DCI-P3	D65	DCI-P3 digital cinema
rgb-adobe-rgb	Adobe RGB	D65	Adobe RGB (1998)
rgb-linear-srgb	Linear sRGB	D65	sRGB without transfer function
rgb-scrgb	scRGB	D65	Extended-range linear sRGB
rgb-apple-rgb	Apple RGB	D65	Apple legacy display

Wide Gamut and Specialty #

Feature	Space	Illuminant	Description
rgb-prophoto-rgb	ProPhoto RGB	D50 *	ROMM RGB for photography
rgb-wide-gamut-rgb	Wide Gamut RGB	D50 *	Adobe Wide Gamut RGB
rgb-best-rgb	Best RGB	D50 *	Wide gamut reference
rgb-beta-rgb	Beta RGB	D50 *	Wide gamut (D50)
rgb-bruce-rgb	Bruce RGB	D65	Bruce Fraser's space
rgb-cie-rgb	CIE RGB	E *	Original CIE RGB (1931)
rgb-colormatch-rgb	ColorMatch RGB	D50 *	Press/prepress proofing
rgb-don-rgb-4	Don RGB 4	D50 *	Wide gamut (D50)
rgb-eci-rgb-v2	ECI RGB v2	D50 *	European Color Initiative
rgb-ektargb-ps5	Ekta Space PS5	D50 *	Kodak Ektachrome space

Entries marked with * implicitly enable the required illuminant feature (illuminant-d50, illuminant-c, or illuminant-e).

Color Spaces #

Non-RGB color spaces available behind individual space-* flags.

CIE Color Spaces #

Feature	Space	Description	Dependencies
space-lab	Lab	CIE 1976 L*a*b* perceptual color space	-
space-lch	LCh	Cylindrical form of CIE L*a*b* (lightness, chroma, hue)	space-lab
space-luv	Luv	CIE 1976 L*u*v* perceptual color space	-
space-lchuv	LChuv	Cylindrical form of CIE L*u*v* (lightness, chroma, hue)	space-luv
space-xyy	xyY	CIE xyY chromaticity + luminance color space	-

Oklab Family #

Feature	Space	Description	Dependencies
space-oklab	Oklab	Perceptual color space for image processing	-
space-oklch	Oklch	Cylindrical form of Oklab	space-oklab
space-okhsl	Okhsl	Perceptually uniform HSL via Oklab	space-oklab
space-okhsv	Okhsv	Perceptually uniform HSV via Oklab	space-oklab
space-okhwb	Okhwb	Perceptually uniform HWB via Oklab	space-okhsv
space-oklab-family	all	Enables Oklab, Oklch, Okhsl, Okhsv, Okhwb	-

HSLuv / HPLuv #

Feature	Space	Description	Dependencies
space-hsluv	HSLuv	Perceptually uniform HSL via CIE LCh(uv)	space-lchuv
space-hpluv	HPLuv	Hue-preserving variant with inscribed-circle S	space-lchuv

Cylindrical (RGB-derived) #

Feature	Space	Description	Dependencies
space-hsi	HSI	Hue, Saturation, Intensity	-
space-hsl	HSL	Hue, Saturation, Lightness	-
space-hsv	HSV/HSB	Hue, Saturation, Value (Brightness)	-
space-hwb	HWB	Hue, Whiteness, Blackness	-

space-hsb is an alias for space-hsv.

Subtractive #

Feature	Space	Description	Dependencies
space-cmy	CMY	Cyan, Magenta, Yellow (complement of RGB)	-
space-cmyk	CMYK	Cyan, Magenta, Yellow, Key/Black	-

Serialization #

Feature	Description
serde	Serialize and Deserialize impls for all color spaces via Serde 1.x

[dependencies]
farg = { version = "0.4", features = ["serde"] }