Dufy - Color Library for Common Lisp

Dufy is a library for exact color manipulation and conversion in various color spaces, which supports the following color models:

• RGB
• XYZ and xyY
• CIELAB and LCh_ab
• CIELUV and LCh_uv
• HSV and HSL
• HSL_uv and HPL_uv
• Munsell Color System
• LMS
• spectrum (as spectral power distribution function)

Dufy can deal with the following concepts:

• Illuminant: A, B, C, D series, F series, etc. A new illuminant can be defined by white point or SPD.
• RGB space: sRGB, Adobe RGB, scRGB, etc. A new RGB space can be defined by primary coordinates, illuminant, method of gamma correction, bit per channel and other encoding characteristics.
• Observer (Color Matching Functions): CIE 1931 2° Standard Observer, CIE 1964 10°. Other observer model can be defined by color matching data.
• Color difference: ΔE^*_ab, CIE94, CIEDE2000, CMC l:c.
• Chromatic adaptaion transform: Bradford, Von Kries, etc. User-defined CAT is also available.

Documentation

Besides this README file, most of the documentation is written as docstrings in the source code. Quickdocs will be helpful to overview them. Some other information (e.g. changes between versions) is in github wiki.

Dependencies

• alexandria
• cl-ppcre

You can install all of the dependent libraries via quicklisp.

Install

The easiest way to install dufy is to use quicklisp:

* (ql:quickload :dufy)

The latest version in this repository can also be loaded with quicklisp:

$ cd ~/quicklisp/local-projects   # the path is held in ql:*local-project-directories*
$ git clone [email protected]:privet-kitty/dufy.git
$ sbcl   # , ccl, etc.

* (ql:register-local-projects)
* (ql:quickload :dufy)

If you want to load the ASDF system directly without quicklisp, you should put the directory of dufy to an appropriate location (e.g. ~/common-lisp/dufy/) and do (asdf:load-system :dufy).

Note that the master branch always coincides with the latest stable release. The develop branch is usually where development happens.

Basic Usage

converter_tree graph G { graph [ labelloc = "t", label = "Tree of Primary Converters", fontsize = 16 ]; node [ shape = "box", fontname = "helvetica", fontsize = 14 ]; xyz [ label = "XYZ" ] xyy [ label = "XYY\n(xyY)" ] lrgb [ label = "LRGB\n(linear RGB)" ] rgb [ label = "RGB\n(gamma-corrected RGB)" ] qrgb [ label = "QRGB\n(quantized RGB)" ] rgbpack [ label = "RGBPACK\n(packed to an int.)" ] rgba [ label = "RGBA\n(gamma-corrected RGBA)" ] qrgba [ label = "QRGBA\n(quantized RGBA)" ] rgbapack [ label = "RGBAPACK\n(packed to an int.)" ] lab [ label = "LAB" ] lchab [ label = "LCHAB" ] luv [ label = "LUV" ] lchuv [ label = "LCHUV" ] mhvc [ label = "MHVC\n(Munsell 3-number spec.)" ] munsell [ label = "MUNSELL\n(Munsell string spec.)" ] hsv [ label = "HSV" ] hsl [ label = "HSL" ] hsluv [ label = "HSLUV" ] hpluv [ label = "HPLUV" ] spectrum [ label = "SPECTRUM" ] lms [ label = "LMS" ] xyz -- xyy xyz -- lms xyz -- spectrum xyz -- lrgb lrgb -- rgb rgb -- qrgb qrgb -- rgbpack

rgba -- qrgba
qrgba -- rgbapack

xyz -- lab
lab -- lchab
xyz -- luv
luv -- lchuv
lchuv -- hsluv
lchuv -- hpluv
rgb -- hsv
rgb -- hsl

lchab -- mhvc  [ label = "(illuminant C)" ]
mhvc -- munsell

{ rank=same; rgb rgba }

} converter_tree

The fundamental color space of dufy is CIE XYZ (Illuminant D65): There are xyz-to- and -to-xyz converters for all other (connected) color spaces. Every converter function just receives numbers and returns multiple numbers:

(dufy:lab-to-xyz 87.07 -78.15 -20.51)  ; L*=87.07, a*=-78.15, b*=-20.51
;; => 0.3731544163010862d0 ; X
;;    0.701492216468595d0  ; Y
;;    1.0600774614243746d0 ; Z
   
(multiple-value-call #'dufy:xyz-to-qrgb
  (dufy:lab-to-xyz 87.07 -78.15 -20.51)
  :clamp nil)
;; => -169 ; R
;;    255  ; G
;;    255  ; B

(multiple-value-call #'dufy:xyz-to-qrgb
  (dufy:lab-to-xyz 87.07 -78.15 -20.51))
;; => 0    ; R
;;    255  ; G
;;    255  ; B

In the second example, a conversion from CIELAB to quantized RGB, xyz-to-qrgb returns a negative R value, which means the color is out of gamut; it is clamped in the third example.

Out of which gamut, however? By default, xyz-to-qrgb (and all other RGB converters) regard it as sRGB (D65). You can specify the RGB space explicitly:

(dufy:xyz-to-qrgb 0.37314 0.70144 1.0601 :rgbspace dufy:+srgb+ :clamp nil)  ; sRGB
;; => -169
;;    255
;;    255

(dufy:xyz-to-qrgb 0.37314 0.70144 1.0601 :rgbspace dufy:+adobe+ :clamp nil) ; Adobe RGB
;; => 2
;;    255
;;    255
   
(dufy:xyz-to-qrgb 0.37314 0.70144 1.0601 :rgbspace dufy:+bg-srgb-10+ :clamp nil) ; bg-sRGB (10 bit)
;; => 47
;;    893
;;    893
;; In the Adobe RGB space and bg-sRGB space the color is within gamut.

Likewise most converters regard the implicit illuminant as D65. You can also specify it explicitly:

(dufy:luv-to-xyz 100 0 0)                              ; Illuminant D65 
(dufy:luv-to-xyz 100 0 0 :illuminant dufy:+illum-d65+) ; Illuminant D65
;; => 0.9504692366968726d0
;;    1.0d0
;;    1.0889440678362423d0
;; the white point of standard illuminant D65

(dufy:luv-to-xyz 100 0 0 :illuminant dufy:+illum-e+)   ; Illuminant E
;; => 1.0d0
;;    1.0d0
;;    1.0000000000000004d0

Modules

Dufy consists of several independent modules:

• dufy
  • dufy/core
  • dufy/hsluv (HSLuv and HPLuv color spaces)
  • dufy/munsell (Munsell Color System)
• dufy/extra-data
• dufy/examples

Since the main package dufy contains slightly large colorimetric data, you may want to load dufy/core instead of dufy in some cases.

As of dufy 0.3.0, both the system names and the package names use the separator / instead of -, though the old package prefixes like dufy-core are left as nicknames.