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ct.el (color tools) is a color library for Emacs meant for making changes to individual colors in various color spaces. Builds on top of color.el and hsluv-emacs, providing a consistent interface to many color spaces, in addition to some utility functions. Visualized in this blog post, used to create tarps. Shouted out by prot (of modus themes fame).

Supported color spaces: rgb • hsl • hsv • hsluv • hpluv • lab • lch

Installation

ct.el is on melpa. You may also install with straight.el:

(straight-use-package '(ct :host github :repo "neeasade/ct.el" :branch "master"))

Conventions

• Colorspace number range values are 0-100
  • Exception: Hue (0-360 degrees)
  • Exception: L*AB* (-100-100)
• Values are clamped to valid ranges coming out of the ct-edit functions
  • Hue is clamped via modulo 360

Functions

Color Properties

• ct-contrast-ratio (C1 C2)
• ct-distance (C1 C2)
• ct-format-argb (C &optional OPACITY END)
• ct-format-rbga (C &optional OPACITY)
• ct-light-p (C &optional SCALE)

Color Modification

• ct-complement (C)
• ct-gradient (STEP START END &optional WITH-ENDS SPACE)
• ct-greaten (C &optional PERCENT)
• ct-lessen (C &optional PERCENT)
• ct-iterate (START OP CONDITION)
• ct-iterations (START OP CONDITION)
• ct-lab-change-whitepoint (C W1 W2)
• ct-mix (COLORS &optional SPACE)
• ct-mix-opacity (TOP BOTTOM OPACITY)
• ct-pastel (C &optional SMOD VMOD)
• ct-tint-ratio (FOREGROUND BACKGROUND RATIO)
• ct-rotation-hpluv (C INTERVAL)
• ct-rotation-hsl (C INTERVAL)
• ct-rotation-hsluv (C INTERVAL)
• ct-rotation-hsv (C INTERVAL)
• ct-rotation-lch (C INTERVAL)

RGB

• ct-make-rgb (R G B)
• ct-get-rgb (C)
• ct-get-rgb-r (C)
• ct-get-rgb-g (C)
• ct-get-rgb-b (C)
• ct-edit-rgb (C TRANSFORM)
• ct-edit-rgb-b (C FUNC-OR-VAL)
• ct-edit-rgb-b-dec (C &optional V)
• ct-edit-rgb-b-inc (C &optional V)
• ct-edit-rgb-g (C FUNC-OR-VAL)
• ct-edit-rgb-g-dec (C &optional V)
• ct-edit-rgb-g-inc (C &optional V)
• ct-edit-rgb-r (C FUNC-OR-VAL)
• ct-edit-rgb-r-dec (C &optional V)
• ct-edit-rgb-r-inc (C &optional V)

LAB

• ct-make-lab (L A B)
• ct-get-lab (C)
• ct-get-lab-l (C)
• ct-get-lab-b (C)
• ct-get-lab-a (C)
• ct-edit-lab (C TRANSFORM)
• ct-edit-lab-a (C FUNC-OR-VAL)
• ct-edit-lab-a-dec (C &optional V)
• ct-edit-lab-a-inc (C &optional V)
• ct-edit-lab-b (C FUNC-OR-VAL)
• ct-edit-lab-b-dec (C &optional V)
• ct-edit-lab-b-inc (C &optional V)
• ct-edit-lab-l (C FUNC-OR-VAL)
• ct-edit-lab-l-dec (C &optional V)
• ct-edit-lab-l-inc (C &optional V)

HSL

• ct-make-hsl (H S L)
• ct-get-hsl (C)
• ct-get-hsl-s (C)
• ct-get-hsl-l (C)
• ct-get-hsl-h (C)
• ct-edit-hsl (C TRANSFORM)
• ct-edit-hsl-h (C FUNC-OR-VAL)
• ct-edit-hsl-h-dec (C &optional V)
• ct-edit-hsl-h-inc (C &optional V)
• ct-edit-hsl-l (C FUNC-OR-VAL)
• ct-edit-hsl-l-dec (C &optional V)
• ct-edit-hsl-l-inc (C &optional V)
• ct-edit-hsl-s (C FUNC-OR-VAL)
• ct-edit-hsl-s-dec (C &optional V)
• ct-edit-hsl-s-inc (C &optional V)

HSLuv

• ct-make-hsluv (H S L)
• ct-get-hsluv (C)
• ct-get-hsluv-s (C)
• ct-get-hsluv-l (C)
• ct-get-hsluv-h (C)
• ct-edit-hsluv (C TRANSFORM)
• ct-edit-hsluv-h (C FUNC-OR-VAL)
• ct-edit-hsluv-h-dec (C &optional V)
• ct-edit-hsluv-h-inc (C &optional V)
• ct-edit-hsluv-l (C FUNC-OR-VAL)
• ct-edit-hsluv-l-dec (C &optional V)
• ct-edit-hsluv-l-inc (C &optional V)
• ct-edit-hsluv-s (C FUNC-OR-VAL)
• ct-edit-hsluv-s-dec (C &optional V)
• ct-edit-hsluv-s-inc (C &optional V)

LCH

• ct-make-lch (L C H)
• ct-get-lch (C)
• ct-get-lch-l (C)
• ct-get-lch-h (C)
• ct-get-lch-c (C)
• ct-edit-lch (C TRANSFORM)
• ct-edit-lch-c (C FUNC-OR-VAL)
• ct-edit-lch-c-dec (C &optional V)
• ct-edit-lch-c-inc (C &optional V)
• ct-edit-lch-h (C FUNC-OR-VAL)
• ct-edit-lch-h-dec (C &optional V)
• ct-edit-lch-h-inc (C &optional V)
• ct-edit-lch-l (C FUNC-OR-VAL)
• ct-edit-lch-l-dec (C &optional V)
• ct-edit-lch-l-inc (C &optional V)

HSV

• ct-make-hsv (H S V)
• ct-get-hsv (C)
• ct-get-hsv-v (C)
• ct-get-hsv-s (C)
• ct-get-hsv-h (C)
• ct-edit-hsv (C TRANSFORM)
• ct-edit-hsv-h (C FUNC-OR-VAL)
• ct-edit-hsv-h-dec (C &optional V)
• ct-edit-hsv-h-inc (C &optional V)
• ct-edit-hsv-s (C FUNC-OR-VAL)
• ct-edit-hsv-s-dec (C &optional V)
• ct-edit-hsv-s-inc (C &optional V)
• ct-edit-hsv-v (C FUNC-OR-VAL)
• ct-edit-hsv-v-dec (C &optional V)
• ct-edit-hsv-v-inc (C &optional V)

HPLUV

• ct-make-hpluv (H P L)
• ct-get-hpluv (C)
• ct-get-hpluv-p (C)
• ct-get-hpluv-l (C)
• ct-get-hpluv-h (C)
• ct-edit-hpluv (C TRANSFORM)
• ct-edit-hpluv-h (C FUNC-OR-VAL)
• ct-edit-hpluv-h-dec (C &optional V)
• ct-edit-hpluv-h-inc (C &optional V)
• ct-edit-hpluv-l (C FUNC-OR-VAL)
• ct-edit-hpluv-l-dec (C &optional V)
• ct-edit-hpluv-l-inc (C &optional V)
• ct-edit-hpluv-p (C FUNC-OR-VAL)
• ct-edit-hpluv-p-dec (C &optional V)
• ct-edit-hpluv-p-inc (C &optional V)

Color Properties

Functions for seeing properties of colors not necessarily related to a particular color space.

ct-contrast-ratio (C1 C2)

Get the contrast ratio between C1 and C2.

(ct-contrast-ratio "#bbbbbb" "#4fa5e8") ;; => 1.3881996647056503

, → 1.3881996647056503

ct-distance (C1 C2)

Get cie-DE2000 distance between C1 and C2 – value is 0-100.

(ct-distance "#4fa5e8" "#bc9a43") ;; => 53.05461635462344

, → 53.05461635462344

ct-format-argb (C &optional OPACITY END)

Argb formatting: Pass in C and OPACITY 0-100, get a string representation of C as follows: ‘#AAFFFFFF’, where AA is a hex pair for the alpha, followed by FF times 3 hex pairs for red, green, blue. If END is truthy, then format will be ‘#FFFFFFAA’.

(ct-format-argb "#4fa5e8" 80 t) ;; => "#4fa5e8cc"

→ #4fa5e8cc

ct-format-rbga (C &optional OPACITY)

RGBA formatting: Pass in C and OPACITY 0-100, get a string representation of C as follows: ‘rgba(R, G, B, OPACITY)’, where values RGB are 0-255, and OPACITY is 0-1.0 (default 1.0).

(ct-format-rbga "#4fa5e8" 80) ;; => "rgba(79, 165, 232, 0.8)"

→ rgba(79, 165, 232, 0.8)

ct-light-p (C &optional SCALE)

Determine if C is a light color with lightness in the LAB space. Optionally override SCALE comparison value.

(ct-light-p "#4fa5e8") ;; => t

→ t

Color Modification

Functions for modifying colors in some way potentially unrelated to a specific colorspace

ct-complement (C)

Return a complement color of C in the HSLUV space.

(ct-complement "#4fa5e8") ;; => "#bc9a43"

→

ct-gradient (STEP START END &optional WITH-ENDS SPACE)

Create a gradient from color START to color END in STEP parts. Optionally include START and END in results using WITH-ENDS. Optionally choose a colorspace with SPACE (see ‘ct–colorspace-map’). Hue-inclusive colorspaces may see mixed results.

(ct-gradient 5 "#4fa5e8" "#bc9a43" t) ;; => ("#4fa5e8" "#6aa2be" "#859f95" "#a09c6c" "#bc9a43")

, → ,,,,

ct-greaten (C &optional PERCENT)

Make a light color C lighter, a dark color C darker (by PERCENT).

(ct-greaten "#4fa5e8" 20) ;; => "#8ddbff"

→

ct-lessen (C &optional PERCENT)

Make a light color C darker, a dark color C lighter (by PERCENT).

(ct-lessen "#4fa5e8" 20) ;; => "#0071af"

→

ct-iterate (START OP CONDITION)

Do OP on START color until CONDITION is met or op has no effect.

(ct-iterate "#4fa5e8" 'ct-edit-hsv-v-inc (lambda (c) (> (ct-distance c "#4fa5e8") 10))) ;; => "#4f98ff"

→

ct-iterations (START OP CONDITION)

Do OP on START color until CONDITION is met or op has no effect - return all intermediate parts.

(ct-iterations "#4fa5e8" 'ct-edit-hsv-v-inc (lambda (c) (> (ct-distance c "#4fa5e8") 10))) ;; => ("#4fa5e8" "#4fa5e9" "#4fa5ea" "#4fa5eb" "#4fa5ec" "#4fa5ed" "#4fa5ee" "#4fa5ef" "#4fa5f0" "#4fa5f1" "#4fa5f2" "#4fa5f3" "#4fa5f4" "#4fa5f5" "#4fa5f6" "#4fa5f7" "#4fa5f8" "#4fa5f9" "#4fa5fa" "#4fa5fb" "#4fa5fc" "#4fa5fd" "#4fa5fe" "#4fa5ff" "#4fa4ff" "#4fa3ff" "#4fa2ff" "#4fa1ff" "#4fa0ff" "#4f9fff" "#4f9eff" "#4f9dff" "#4f9cff" "#4f9bff" "#4f9aff" "#4f99ff" "#4f98ff")

→ ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

ct-lab-change-whitepoint (C W1 W2)

Convert a color C wrt white points W1 and W2 through the lab colorspace.

(ct-lab-change-whitepoint "#4fa5e8" color-d50-xyz color-d55-xyz) ;; => "#29a6f4"

→

ct-mix (COLORS &optional SPACE)

Mix COLORS in space SPACE. See also: ‘ct–colorspace-map’.

(ct-mix (list "#4fa5e8" "#bbbbbb" "#bc9a43")) ;; => "#a0a48a"

→

ct-mix-opacity (TOP BOTTOM OPACITY)

Get resulting color of TOP color with OPACITY overlayed against BOTTOM. Opacity is expected to be 0.0-1.0.

(ct-mix-opacity "#4fa5e8" "#bbbbbb" 80) ;; => "#0000ff"

, →

ct-pastel (C &optional SMOD VMOD)

Make a color C more ‘pastel’ in the hsluv space – optionally change the rate of change with SMOD and VMOD.

(ct-pastel "#4fa5e8") ;; => "#77a2c4"

→

ct-tint-ratio (FOREGROUND BACKGROUND RATIO)

Tint a FOREGROUND against BACKGROUND until contrast RATIO minimum is reached.

(ct-tint-ratio "#4fa5e8" "#bbbbbb" 3) ;; => "#1369ac"

, →

ct-rotation-hpluv (C INTERVAL)

Perform a hue rotation in hpluv space starting with color C by INTERVAL degrees.

(ct-rotation-hpluv "#4fa5e8" 60) ;; => ("#72a2d2" "#c48acb" "#d78895" "#b89a59" "#74ac68" "#03b1a7")

→ ,,,,,

ct-rotation-hsl (C INTERVAL)

Perform a hue rotation in hsl space starting with color C by INTERVAL degrees.

(ct-rotation-hsl "#4fa5e8" 60) ;; => ("#4fa4e8" "#914fe8" "#e84fa4" "#e8914f" "#a5e84f" "#4fe892")

→ ,,,,,

ct-rotation-hsluv (C INTERVAL)

Perform a hue rotation in hsluv space starting with color C by INTERVAL degrees.

(ct-rotation-hsluv "#4fa5e8" 60) ;; => ("#4ea5e7" "#e173ec" "#f0798f" "#bc9a43" "#5cb143" "#48ada5")

→ ,,,,,

ct-rotation-hsv (C INTERVAL)

Perform a hue rotation in hsv space starting with color C by INTERVAL degrees.

(ct-rotation-hsv "#4fa5e8" 60) ;; => ("#4ea5e8" "#914ee8" "#e84ea5" "#e8924e" "#a5e84e" "#4ee892")

→ ,,,,,

ct-rotation-lch (C INTERVAL)

Perform a hue rotation in lch space starting with color C by INTERVAL degrees.

(ct-rotation-lch "#4fa5e8" 60) ;; => ("#4fa4e8" "#c48acc" "#e58183" "#bd9953" "#6dad6f" "#00b1ba")

→ ,,,,,

RGB

https://notes.neeasade.net/color-spaces.html#h-99356355-d54c-41d8-bc1a-6e14e29f42c8

ct-make-rgb (R G B)

Make a color using R*G*B properties.

(ct-make-rgb 30.980392156862745 64.70588235294117 90.98039215686275) ;; => "#4fa4e8"

→

ct-get-rgb (C)

Get rgb representation of color C.

(ct-get-rgb "#4fa5e8") ;; => (30.980392156862745 64.70588235294117 90.98039215686275)

→ (30.980392156862745 64.70588235294117 90.98039215686275)

ct-get-rgb-r (C)

Get rgb-r representation of color C.

(ct-get-rgb-r "#4fa5e8") ;; => 30.980392156862745

→ 30.980392156862745

ct-get-rgb-g (C)

Get rgb-g representation of color C.

(ct-get-rgb-g "#4fa5e8") ;; => 64.70588235294117

→ 64.70588235294117

ct-get-rgb-b (C)

Get rgb-b representation of color C.

(ct-get-rgb-b "#4fa5e8") ;; => 90.98039215686275

→ 90.98039215686275

ct-edit-rgb (C TRANSFORM)

Work with a color C in the RGB space using function TRANSFORM. Ranges for RGB are all 0-100.

(ct-edit-rgb "#4fa5e8" (lambda (R G B) (list R 0 0))) ;; => "#4f0000"

→

ct-edit-rgb-b (C FUNC-OR-VAL)

Transform property rgb-b of C using FUNC-OR-VAL.

(ct-edit-rgb-b "#4fa5e8" (lambda (b) (+ b 50))) ;; => "#4fa4ff"

→

ct-edit-rgb-b-dec (C &optional V)

Decrease rgb-b value of C by V (defaults to the minimum amount needed to change C).

(ct-edit-rgb-b-dec "#bbbbbb" 10) ;; => "#bbbba1"

→

ct-edit-rgb-b-inc (C &optional V)

Increase rgb-b value of C by V (defaults to the minimum amount needed to change C).

(ct-edit-rgb-b-inc "#bbbbbb") ;; => "#bbbbbc"

ct-edit-rgb-g (C FUNC-OR-VAL)

Transform property rgb-g of C using FUNC-OR-VAL.

(ct-edit-rgb-g "#4fa5e8" 100) ;; => "#4fffe8"

→

ct-edit-rgb-g-dec (C &optional V)

Decrease rgb-g value of C by V (defaults to the minimum amount needed to change C).

(ct-edit-rgb-g-dec "#bbbbbb" 10) ;; => "#bba1bb"

→

ct-edit-rgb-g-inc (C &optional V)

Increase rgb-g value of C by V (defaults to the minimum amount needed to change C).

(ct-edit-rgb-g-inc "#bbbbbb") ;; => "#bbbcbb"

ct-edit-rgb-r (C FUNC-OR-VAL)

Transform property rgb-r of C using FUNC-OR-VAL.

(ct-edit-rgb-r "#4fa5e8" 100) ;; => "#ffa4e8"

→

ct-edit-rgb-r-dec (C &optional V)

Decrease rgb-r value of C by V (defaults to the minimum amount needed to change C).

(ct-edit-rgb-r-dec "#bbbbbb" 10) ;; => "#a1bbbb"

→

ct-edit-rgb-r-inc (C &optional V)

Increase rgb-r value of C by V (defaults to the minimum amount needed to change C).

(ct-edit-rgb-r-inc "#bbbbbb") ;; => "#bcbbbb"

LAB

https://notes.neeasade.net/color-spaces.html#h-9d5a1a9a-75d3-48f5-bf00-85332d9b023e

ct-make-lab (L A B)

Make a color using L*A*B properties.

(ct-make-lab 65.27524119433272 -5.264411618969234 -41.33308089969405) ;; => "#4fa4e8"

→

ct-get-lab (C)

Get lab representation of color C.

(ct-get-lab "#4fa5e8") ;; => (65.27524119433272 -5.264411618969234 -41.33308089969405)

→ (65.27524119433272 -5.264411618969234 -41.33308089969405)

ct-get-lab-l (C)

Get lab-l representation of color C.

(ct-get-lab-l "#4fa5e8") ;; => 65.27524119433272

→ 65.27524119433272

ct-get-lab-b (C)

Get lab-b representation of color C.

(ct-get-lab-b "#4fa5e8") ;; => -41.33308089969405

→ -41.33308089969405

ct-get-lab-a (C)

Get lab-a representation of color C.

(ct-get-lab-a "#4fa5e8") ;; => -5.264411618969234

→ -5.264411618969234

ct-edit-lab (C TRANSFORM)

Work with a color C in the LAB space using function TRANSFORM. Ranges for LAB are {0-100,-100-100,-100-100}.

(ct-edit-lab "#4fa5e8" (lambda (L A B) (list L -100 -100))) ;; => "#00ccff"

→

ct-edit-lab-a (C FUNC-OR-VAL)

Transform property lab-a of C using FUNC-OR-VAL.

(ct-edit-lab-a "#4fa5e8" (lambda (a) (- a 20))) ;; => "#00aee7"

→

ct-edit-lab-a-dec (C &optional V)

Decrease lab-a value of C by V (defaults to the minimum amount needed to change C).

(ct-edit-lab-a-dec "#4fa5e8" 20) ;; => "#00aee7"

→

ct-edit-lab-a-inc (C &optional V)

Increase lab-a value of C by V (defaults to the minimum amount needed to change C).

(ct-edit-lab-a-inc "#4fa5e8" 20) ;; => "#8c99e8"

→

ct-edit-lab-b (C FUNC-OR-VAL)

Transform property lab-b of C using FUNC-OR-VAL.

(ct-edit-lab-b "#4fa5e8" 100) ;; => "#b79e00"

→

ct-edit-lab-b-dec (C &optional V)

Decrease lab-b value of C by V (defaults to the minimum amount needed to change C).

(ct-edit-lab-b-dec "#4fa5e8" 20) ;; => "#00a7ff"

→

ct-edit-lab-b-inc (C &optional V)

Increase lab-b value of C by V (defaults to the minimum amount needed to change C).

(ct-edit-lab-b-inc "#4fa5e8" 20) ;; => "#7aa3c4"

→

ct-edit-lab-l (C FUNC-OR-VAL)

Transform property lab-l of C using FUNC-OR-VAL.

(ct-edit-lab-l "#4fa5e8" 0) ;; => "#000a3d"

→

ct-edit-lab-l-dec (C &optional V)

Decrease lab-l value of C by V (defaults to the minimum amount needed to change C).

(ct-edit-lab-l-dec "#4fa5e8") ;; => "#4ea4e7"

ct-edit-lab-l-inc (C &optional V)

Increase lab-l value of C by V (defaults to the minimum amount needed to change C).

(ct-edit-lab-l-inc "#4fa5e8") ;; => "#50a5e8"

HSL

https://notes.neeasade.net/color-spaces.html#h-43869bc7-a7d1-410f-9341-521974751dac

ct-make-hsl (H S L)

Make a color using H*S*L properties.

(ct-make-hsl 206.27450980392157 76.88442211055275 60.98039215686275) ;; => "#4fa4e8"

→

ct-get-hsl (C)

Get hsl representation of color C.

(ct-get-hsl "#4fa5e8") ;; => (206.27450980392157 76.88442211055275 60.98039215686275)

→ (206.27450980392157 76.88442211055275 60.98039215686275)

ct-get-hsl-s (C)

Get hsl-s representation of color C.

(ct-get-hsl-s "#4fa5e8") ;; => 76.88442211055275

→ 76.88442211055275

ct-get-hsl-l (C)

Get hsl-l representation of color C.

(ct-get-hsl-l "#4fa5e8") ;; => 60.98039215686275

→ 60.98039215686275

ct-get-hsl-h (C)

Get hsl-h representation of color C.

(ct-get-hsl-h "#4fa5e8") ;; => 206.27450980392157

→ 206.27450980392157

ct-edit-hsl (C TRANSFORM)

Work with a color C in the HSL space using function TRANSFORM. Ranges for HSL are {0-360,0-100,0-100}.

(ct-edit-hsl "#4fa5e8" (lambda (H S L) (list (+ H 60) 100 L))) ;; => "#8f38ff"

→

ct-edit-hsl-h (C FUNC-OR-VAL)

Transform property hsl-h of C using FUNC-OR-VAL.

(ct-edit-hsl-h "#4fa5e8" (lambda (H) (+ H 60))) ;; => "#914fe8"

→

ct-edit-hsl-h-dec (C &optional V)

Decrease hsl-h value of C by V (defaults to the minimum amount needed to change C).

(ct-edit-hsl-h-dec "#4fa5e8") ;; => "#4fa6e8"

ct-edit-hsl-h-inc (C &optional V)

Increase hsl-h value of C by V (defaults to the minimum amount needed to change C).

(ct-edit-hsl-h-inc "#4fa5e8") ;; => "#4fa4e8"

ct-edit-hsl-l (C FUNC-OR-VAL)

Transform property hsl-l of C using FUNC-OR-VAL.

(ct-edit-hsl-l "#4fa5e8" 0) ;; => "#000000"

→

ct-edit-hsl-l-dec (C &optional V)

Decrease hsl-l value of C by V (defaults to the minimum amount needed to change C).

(ct-edit-hsl-l-dec "#4fa5e8") ;; => "#4ea4e7"

ct-edit-hsl-l-inc (C &optional V)

Increase hsl-l value of C by V (defaults to the minimum amount needed to change C).

(ct-edit-hsl-l-inc "#4fa5e8") ;; => "#50a5e8"

ct-edit-hsl-s (C FUNC-OR-VAL)

Transform property hsl-s of C using FUNC-OR-VAL.

(ct-edit-hsl-s "#4fa5e8" 100) ;; => "#38a7ff"

→

ct-edit-hsl-s-dec (C &optional V)

Decrease hsl-s value of C by V (defaults to the minimum amount needed to change C).

(ct-edit-hsl-s-dec "#4fa5e8") ;; => "#4fa4e7"

ct-edit-hsl-s-inc (C &optional V)

Increase hsl-s value of C by V (defaults to the minimum amount needed to change C).

(ct-edit-hsl-s-inc "#4fa5e8") ;; => "#4ea5e8"

HSLuv

https://notes.neeasade.net/color-spaces.html#h-c147b84d-d95b-4d2d-8426-2f96529a8428

ct-make-hsluv (H S L)

Make a color using H*S*L*uv properties.

(ct-make-hsluv 242.63535329133538 81.00935604214261 65.27665592005344) ;; => "#4ea5e7"

→

ct-get-hsluv (C)

Get hsluv representation of color C.

(ct-get-hsluv "#4fa5e8") ;; => (242.63535329133538 81.00935604214261 65.27665592005344)

→ (242.63535329133538 81.00935604214261 65.27665592005344)

ct-get-hsluv-s (C)

Get hsluv-s representation of color C.

(ct-get-hsluv-s "#4fa5e8") ;; => 81.00935604214261

→ 81.00935604214261

ct-get-hsluv-l (C)

Get hsluv-l representation of color C.

(ct-get-hsluv-l "#4fa5e8") ;; => 65.27665592005344

→ 65.27665592005344

ct-get-hsluv-h (C)

Get hsluv-h representation of color C.

(ct-get-hsluv-h "#4fa5e8") ;; => 242.63535329133538

→ 242.63535329133538

ct-edit-hsluv (C TRANSFORM)

Work with a color C in the HSLUV space using function TRANSFORM. Ranges for HSLUV are {0-360,0-100,0-100}.

(ct-edit-hsluv "#4fa5e8" (lambda (H S L) (list (+ H 60) 100 L))) ;; => "#f160ff"

→

ct-edit-hsluv-h (C FUNC-OR-VAL)

Transform property hsluv-h of C using FUNC-OR-VAL.

(ct-edit-hsluv-h "#4fa5e8" (lambda (H) (+ H 60))) ;; => "#e173ec"

→

ct-edit-hsluv-h-dec (C &optional V)

Decrease hsluv-h value of C by V (defaults to the minimum amount needed to change C).

(ct-edit-hsluv-h-dec "#4fa5e8") ;; => "#4ea5e7"

ct-edit-hsluv-h-inc (C &optional V)

Increase hsluv-h value of C by V (defaults to the minimum amount needed to change C).

(ct-edit-hsluv-h-inc "#4fa5e8") ;; => "#4fa4e8"

ct-edit-hsluv-l (C FUNC-OR-VAL)

Transform property hsluv-l of C using FUNC-OR-VAL.

(ct-edit-hsluv-l "#4fa5e8" 0) ;; => "#000000"

→

ct-edit-hsluv-l-dec (C &optional V)

Decrease hsluv-l value of C by V (defaults to the minimum amount needed to change C).

(ct-edit-hsluv-l-dec "#4fa5e8") ;; => "#4ea4e7"

ct-edit-hsluv-l-inc (C &optional V)

Increase hsluv-l value of C by V (defaults to the minimum amount needed to change C).

(ct-edit-hsluv-l-inc "#4fa5e8") ;; => "#4fa5e9"

ct-edit-hsluv-s (C FUNC-OR-VAL)

Transform property hsluv-s of C using FUNC-OR-VAL.

(ct-edit-hsluv-s "#4fa5e8" 100) ;; => "#00a6f8"

→

ct-edit-hsluv-s-dec (C &optional V)

Decrease hsluv-s value of C by V (defaults to the minimum amount needed to change C).

(ct-edit-hsluv-s-dec "#4fa5e8") ;; => "#4fa4e7"

ct-edit-hsluv-s-inc (C &optional V)

Increase hsluv-s value of C by V (defaults to the minimum amount needed to change C).

(ct-edit-hsluv-s-inc "#4fa5e8") ;; => "#4ea5e8"

LCH

https://notes.neeasade.net/color-spaces.html#h-c4f93e1f-4fa6-4ebc-99c1-18b6de0ef413

ct-make-lch (L C H)

Make a color using L*C*H properties.

(ct-make-lch 65.27524119433272 41.666984608375394 -97.25842954163491) ;; => "#4fa4e8"

→

ct-get-lch (C)

Get lch representation of color C.

(ct-get-lch "#4fa5e8") ;; => (65.27524119433272 41.666984608375394 -97.25842954163491)

→ (65.27524119433272 41.666984608375394 -97.25842954163491)

ct-get-lch-l (C)

Get lch-l representation of color C.

(ct-get-lch-l "#4fa5e8") ;; => 65.27524119433272

→ 65.27524119433272

ct-get-lch-h (C)

Get lch-h representation of color C.

(ct-get-lch-h "#4fa5e8") ;; => -97.25842954163491

→ -97.25842954163491

ct-get-lch-c (C)

Get lch-c representation of color C.

(ct-get-lch-c "#4fa5e8") ;; => 41.666984608375394

→ 41.666984608375394

ct-edit-lch (C TRANSFORM)

Work with a color C in the LCH space using function TRANSFORM. Ranges for LCH are {0-100,0-100,0-360}.

(ct-edit-lch "#4fa5e8" (lambda (L C H) (list L 100 (+ H 90)))) ;; => "#ff00b8"

→

ct-edit-lch-c (C FUNC-OR-VAL)

Transform property lch-c of C using FUNC-OR-VAL.

(ct-edit-lch-c "#4fa5e8" 100) ;; => "#00b0ff"

→

ct-edit-lch-c-dec (C &optional V)

Decrease lch-c value of C by V (defaults to the minimum amount needed to change C).

(ct-edit-lch-c-dec "#4fa5e8") ;; => "#4fa4e7"

ct-edit-lch-c-inc (C &optional V)

Increase lch-c value of C by V (defaults to the minimum amount needed to change C).

(ct-edit-lch-c-inc "#4fa5e8") ;; => "#4ea5e8"

ct-edit-lch-h (C FUNC-OR-VAL)

Transform property lch-h of C using FUNC-OR-VAL.

(ct-edit-lch-h "#4fa5e8" (lambda (H) (+ H 90))) ;; => "#df81a9"

→

ct-edit-lch-h-dec (C &optional V)

Decrease lch-h value of C by V (defaults to the minimum amount needed to change C).

(ct-edit-lch-h-dec "#4fa5e8") ;; => "#4ea5e7"

ct-edit-lch-h-inc (C &optional V)

Increase lch-h value of C by V (defaults to the minimum amount needed to change C).

(ct-edit-lch-h-inc "#4fa5e8") ;; => "#4fa4e8"

ct-edit-lch-l (C FUNC-OR-VAL)

Transform property lch-l of C using FUNC-OR-VAL.

(ct-edit-lch-l "#4fa5e8" 100) ;; => "#baffff"

→

ct-edit-lch-l-dec (C &optional V)

Decrease lch-l value of C by V (defaults to the minimum amount needed to change C).

(ct-edit-lch-l-dec "#4fa5e8") ;; => "#4ea4e7"

ct-edit-lch-l-inc (C &optional V)

Increase lch-l value of C by V (defaults to the minimum amount needed to change C).

(ct-edit-lch-l-inc "#4fa5e8") ;; => "#50a5e8"

HSV

https://en.wikipedia.org/wiki/HSL_and_HSV

ct-make-hsv (H S V)

Make a color using H*S*V properties.

(ct-make-hsv 206.27450980392157 65.94827586206897 90.98039215686275) ;; => "#4ea5e8"

→

ct-get-hsv (C)

Get hsv representation of color C.

(ct-get-hsv "#4fa5e8") ;; => (206.27450980392157 65.94827586206897 90.98039215686275)

→ (206.27450980392157 65.94827586206897 90.98039215686275)

ct-get-hsv-v (C)

Get hsv-v representation of color C.

(ct-get-hsv-v "#4fa5e8") ;; => 90.98039215686275

→ 90.98039215686275

ct-get-hsv-s (C)

Get hsv-s representation of color C.

(ct-get-hsv-s "#4fa5e8") ;; => 65.94827586206897

→ 65.94827586206897

ct-get-hsv-h (C)

Get hsv-h representation of color C.

(ct-get-hsv-h "#4fa5e8") ;; => 206.27450980392157

→ 206.27450980392157

ct-edit-hsv (C TRANSFORM)

Work with a color C in the HSV space using function TRANSFORM. Ranges for HSV are {0-360,0-100,0-100}.

(ct-edit-hsv "#4fa5e8" (lambda (H S V) (list H 20 100))) ;; => "#cce8ff"

→

ct-edit-hsv-h (C FUNC-OR-VAL)

Transform property hsv-h of C using FUNC-OR-VAL.

(ct-edit-hsv-h "#4fa5e8" (-partial #'+ 30)) ;; => "#4e58e8"

→

ct-edit-hsv-h-dec (C &optional V)

Decrease hsv-h value of C by V (defaults to the minimum amount needed to change C).

(ct-edit-hsv-h-dec "#4fa5e8") ;; => "#4ea5e8"

ct-edit-hsv-h-inc (C &optional V)

Increase hsv-h value of C by V (defaults to the minimum amount needed to change C).

(ct-edit-hsv-h-inc "#4fa5e8") ;; => "#4ea4e8"

ct-edit-hsv-s (C FUNC-OR-VAL)

Transform property hsv-s of C using FUNC-OR-VAL.

(ct-edit-hsv-s "#4fa5e8" 20) ;; => "#b9d3e8"

→

ct-edit-hsv-s-dec (C &optional V)

Decrease hsv-s value of C by V (defaults to the minimum amount needed to change C).

(ct-edit-hsv-s-dec "#4fa5e8") ;; => "#50a5e8"

ct-edit-hsv-s-inc (C &optional V)

Increase hsv-s value of C by V (defaults to the minimum amount needed to change C).

(ct-edit-hsv-s-inc "#4fa5e8") ;; => "#4ea4e8"

ct-edit-hsv-v (C FUNC-OR-VAL)

Transform property hsv-v of C using FUNC-OR-VAL.

(ct-edit-hsv-v "#4fa5e8" 100) ;; => "#56b5ff"

→

ct-edit-hsv-v-dec (C &optional V)

Decrease hsv-v value of C by V (defaults to the minimum amount needed to change C).

(ct-edit-hsv-v-dec "#4fa5e8") ;; => "#4ea4e7"

ct-edit-hsv-v-inc (C &optional V)

Increase hsv-v value of C by V (defaults to the minimum amount needed to change C).

(ct-edit-hsv-v-inc "#4fa5e8") ;; => "#4fa5e9"

HPLUV

https://ajalt.github.io/colormath/api/colormath/com.github.ajalt.colormath.model/-h-p-luv/index.html

ct-make-hpluv (H P L)

Make a color using H*P*L*uv properties.

(ct-make-hpluv 242.63535329133538 143.13047428079187 65.27665592005344) ;; => "#72a2d2"

→

ct-get-hpluv (C)

Get hpluv representation of color C.

(ct-get-hpluv "#4fa5e8") ;; => (242.63535329133538 143.13047428079187 65.27665592005344)

→ (242.63535329133538 143.13047428079187 65.27665592005344)

ct-get-hpluv-p (C)

Get hpluv-p representation of color C.

(ct-get-hpluv-p "#4fa5e8") ;; => 143.13047428079187

→ 143.13047428079187

ct-get-hpluv-l (C)

Get hpluv-l representation of color C.

(ct-get-hpluv-l "#4fa5e8") ;; => 65.27665592005344

→ 65.27665592005344

ct-get-hpluv-h (C)

Get hpluv-h representation of color C.

(ct-get-hpluv-h "#4fa5e8") ;; => 242.63535329133538

→ 242.63535329133538

ct-edit-hpluv (C TRANSFORM)

Work with a color C in the HPLUV space using function TRANSFORM. Ranges for HPLUV are {0-360,0-100,0-100}.

(ct-edit-hpluv "#4fa5e8" (lambda (H P L) (list H 100 L))) ;; => "#72a2d2"

→

ct-edit-hpluv-h (C FUNC-OR-VAL)

Transform property hpluv-h of C using FUNC-OR-VAL.

(ct-edit-hpluv-h "#4fa5e8" 0) ;; => "#d78798"

→

ct-edit-hpluv-h-dec (C &optional V)

Decrease hpluv-h value of C by V (defaults to the minimum amount needed to change C).

(ct-edit-hpluv-h-dec "#4fa5e8") ;; => "#71a2d2"

ct-edit-hpluv-h-inc (C &optional V)

Increase hpluv-h value of C by V (defaults to the minimum amount needed to change C).

(ct-edit-hpluv-h-inc "#4fa5e8") ;; => "#72a2d2"

ct-edit-hpluv-l (C FUNC-OR-VAL)

Transform property hpluv-l of C using FUNC-OR-VAL.

(ct-edit-hpluv-l "#4fa5e8" 100) ;; => "#feffff"

→

ct-edit-hpluv-l-dec (C &optional V)

Decrease hpluv-l value of C by V (defaults to the minimum amount needed to change C).

(ct-edit-hpluv-l-dec "#4fa5e8") ;; => "#71a2d2"

ct-edit-hpluv-l-inc (C &optional V)

Increase hpluv-l value of C by V (defaults to the minimum amount needed to change C).

(ct-edit-hpluv-l-inc "#4fa5e8") ;; => "#72a3d3"

ct-edit-hpluv-p (C FUNC-OR-VAL)

Transform property hpluv-p of C using FUNC-OR-VAL.

(ct-edit-hpluv-p "#4fa5e8" 100) ;; => "#72a2d2"

→

ct-edit-hpluv-p-dec (C &optional V)

Decrease hpluv-p value of C by V (defaults to the minimum amount needed to change C).

(ct-edit-hpluv-p-dec "#4fa5e8") ;; => "#72a2d2"

ct-edit-hpluv-p-inc (C &optional V)

Increase hpluv-p value of C by V (defaults to the minimum amount needed to change C).

(ct-edit-hpluv-p-inc "#4fa5e8") ;; => "#72a2d2"

Gotchas

Some colors as defined in color spaces may not be represented in the RGB space (and vice versa). The edit functions clamp values going out. One example is the narrowly scoped hpluv space:

(ct-get-hpluv "#dd00cc")

;; That p value is way out of range!
;; => (314.3830496716472 282.01497572464575 51.53528501195089)

;; notice we ask for the same color back, but the transform functions clamp the output to maximum HPL values:
(ct-edit-hpluv "#dd00cc" 'list)

;; => "#9f6898"

Testing

Right now testing happens by using the `ct-make-*` functions(these use the transform functions, which make up the basis for all the color space functions) against:

• https://css.land/lch/
• http://colorizer.org/

Related links

Emacs color libraries:

• https:/emacs-mirror/emacs/blob/master/lisp/color.el
• https:/emacsfodder/kurecolor
• https:/yurikhan/yk-color
• https:/hsluv/hsluv-emacs

General color knowledge:

• http://colorizer.org/
• https://peteroupc.github.io/colorgen.html
• https://www.w3.org/TR/WCAG20/#relativeluminancedef
• https://en.wikipedia.org/wiki/CIELAB_color_space