Module:Color

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This Lua module is used on approximately 620 pages and changes may be widely noticed. Test changes in the module's /sandbox or /testcases subpages, or in your own module sandbox. Consider discussing changes on the talk page before implementing them.

This module is used primarily by {{Infobox color}}, eliminating the need for external color converters and preventing mismatch between color coordinates.

Usage

To use this module, you may use one of the above listed templates or invoke the module directly. All functions that accept hexadecimal triplets also handle the shorthand three-digit format.

To convert a hexadecimal triplet to an RGB triplet as comma-separated values:

{{#invoke:Color|hexToRgbTriplet|color}}

To convert a hexadecimal triplet to the CMYK color model without a color profile (which is a very bad idea!):

{{#invoke:Color|hexToCmyk|color|precision=?|pctsign=?}}

To convert a hexadecimal triplet to HSL or HSV:

{{#invoke:Color|hexToHsl|color|precision=?}}

{{#invoke:Color|hexToHsv|color|precision=?}}

To convert a hexadecimal triplet to the perceptual CIELCh_uv color space:

{{#invoke:Color|hexToCielch|color|precision=?}}

To mix two colors in the more physically correct linear RGB space:

{{#invoke:Color|hexMix|color1|color2|proportion|min=?|max=?}}

To convert an RGB triplet to a hex code:

{{#invoke:Color|rgbTripletToHex|r|g|b}}

The following parameters are optional:

precision: defaults to 0 (zero)
pctsign: set to 0 (zero) to suppress percent signs in the generated output
proportion: proportion of color2, defaults to 50
min: minimum value of proportion range, defaults to 0
max: maximum value of proportion range, defaults to 100

-- Introduction: https://colorspace.r-forge.r-project.org/articles/color_spaces.html

local p = {}

local function isempty(v)
	return v == nil or v == ''
end

local function hexToRgb(color)
	local cleanColor = color:gsub("&#35;", "#"):match('^[%s#]*(.-)[%s;]*$')
	if (#cleanColor == 6) then
		return {
			r = tonumber(string.sub(cleanColor, 1, 2), 16),
			g = tonumber(string.sub(cleanColor, 3, 4), 16),
			b = tonumber(string.sub(cleanColor, 5, 6), 16)
		}
	elseif (#cleanColor == 3) then
		return {
			r = 17 * tonumber(string.sub(cleanColor, 1, 1), 16),
			g = 17 * tonumber(string.sub(cleanColor, 2, 2), 16),
			b = 17 * tonumber(string.sub(cleanColor, 3, 3), 16)
		}
	end
	error("Invalid hexadecimal color " .. cleanColor, 1)
end

local function round(v)
	if (v < 0) then
		return math.ceil(v - 0.5)
	else
		return math.floor(v + 0.5)
	end
end

local function rgbToHex(r, g, b)
	return string.format("%02X%02X%02X", round(r), round(g), round(b))
end

local function rgbToCmyk(r, g, b)
	if (r > 255 or g > 255 or b > 255 or r < 0 or g < 0 or b < 0) then
		error("Color level out of bounds")
	end
	local c = 1 - r / 255
	local m = 1 - g / 255
	local y = 1 - b / 255
	local k = math.min(c, m, y)
	if (k == 1) then
		c = 0
		m = 0
		y = 0
	else
		local d = 1 - k
		c = (c - k) / d
		m = (m - k) / d
		y = (y - k) / d
	end
	return { c = c * 100, m = m * 100, y = y * 100, k = k * 100 }
end

local function rgbToHsl(r, g, b)
	if (r > 255 or g > 255 or b > 255 or r < 0 or g < 0 or b < 0) then
		error("Color level out of bounds")
	end
	local channelMax = math.max(r, g, b)
	local channelMin = math.min(r, g, b)
	local range = channelMax - channelMin
	local h, s
	if (range == 0) then
		h = 0
	elseif (channelMax == r) then
		h = 60 * ((g - b) / range)
		if (h < 0) then
			h = 360 + h
		end
	elseif (channelMax == g) then
		h = 60 * (2 + (b - r) / range)
	else
		h = 60 * (4 + (r - g) / range)
	end
	local L = channelMax + channelMin
	if (L == 0 or L == 510) then
		s = 0
	else
		s = 100 * range / math.min(L, 510 - L)
	end
	return { h = h, s = s, l = L * 50 / 255 }
end

local function rgbToHsv(r, g, b)
	if (r > 255 or g > 255 or b > 255 or r < 0 or g < 0 or b < 0) then
		error("Color level out of bounds")
	end
	local channelMax = math.max(r, g, b)
	local channelMin = math.min(r, g, b)
	local range = channelMax - channelMin
	local h, s
	if (range == 0) then
		h = 0
	elseif (channelMax == r) then
		h = 60 * ((g - b) / range)
		if (h < 0) then
			h = 360 + h
		end
	elseif (channelMax == g) then
		h = 60 * (2 + (b - r) / range)
	else
		h = 60 * (4 + (r - g) / range)
	end
	if (channelMax == 0) then
		s = 0
	else
		s = 100 * range / channelMax
	end
	return { h = h, s = s, v = channelMax * 100 / 255 }
end

-- c in [0, 255], condition tweaked for no discontinuity
-- http://entropymine.com/imageworsener/srgbformula/
local function toLinear(c)
	if (c > 10.314300250662591) then
		return math.pow((c + 14.025) / 269.025, 2.4)
	else
		return c / 3294.6
	end
end

local function toNonLinear(c)
	if (c > 0.00313066844250063) then
		return 269.025 * math.pow(c, 1.0/2.4) - 14.025
	else
		return 3294.6 * c
	end
end

local function srgbToCielchuvD65o2deg(r, g, b)
	if (r > 255 or g > 255 or b > 255 or r < 0 or g < 0 or b < 0) then
		error("Color level out of bounds")
	end
	local R = toLinear(r)
	local G = toLinear(g)
	local B = toLinear(b)
	-- https://github.com/w3c/csswg-drafts/issues/5922
	local X = 0.1804807884018343 * B + 0.357584339383878 * G + 0.41239079926595934 * R
	local Y = 0.07219231536073371 * B + 0.21263900587151027 * R + 0.715168678767756 * G
	local Z = 0.01933081871559182 * R + 0.11919477979462598 * G + 0.9505321522496607 * B
	local L, C, h
	if (Y > 0.00885645167903563082) then
		L = 116 * math.pow(Y, 1/3) - 16
	else
		L = Y * 903.2962962962962962963
	end
	if ((r == g and g == b) or L == 0) then
		C = 0
		h = 0
	else
		d = X + 3 * Z + 15 * Y
		if (d == 0) then
			C = 0
			h = 0
		else
			-- 0.19783... and 0.4631... computed with extra precision from (X,Y,Z) when (R,G,B) = (1,1,1),
			-- in which case (u,v) ≈ (0,0)
			local us = 4 * X / d - 0.19783000664283678994
			local vs = 9 * Y / d - 0.46831999493879099801
			h = math.atan2(vs, us) * 57.2957795130823208768
			if (h < 0) then
				h = h + 360
			elseif (h == 0) then
				h = 0 -- ensure zero is positive
			end
			C = math.sqrt(us * us + vs * vs) * 13 * L
			if (C == 0) then
				C = 0
				h = 0
			end
		end
	end
	return { L = L, C = C, h = h }
end

local function srgbMix(t, r0, g0, b0, r1, g1, b1)
	if (t > 1 or t < 0) then
		error("Interpolation parameter out of bounds")
	end
	if (r0 > 255 or g0 > 255 or b0 > 255 or r1 > 255 or g1 > 255 or b1 > 255 or r0 < 0 or g0 < 0 or b0 < 0 or r1 < 0 or g1 < 0 or b1 < 0) then
		error("Color level out of bounds")
	end
	local tc = 1 - t
	return {
		r = toNonLinear(tc * toLinear(r0) + t * toLinear(r1)),
		g = toNonLinear(tc * toLinear(g0) + t * toLinear(g1)),
		b = toNonLinear(tc * toLinear(b0) + t * toLinear(b1))
	}
end

local function formatToPrecision(value, p)
	return string.format("%." .. p .. "f", value)
end

local function getFractionalZeros(p)
	if (p > 0) then
		return "." .. string.rep("0", p)
	else
		return ""
	end
end

function p.hexToRgbTriplet(frame)
	local args = frame.args or frame:getParent().args
	local hex = args[1]
	if (hex) then
		local rgb = hexToRgb(hex)
		return rgb.r .. ', ' .. rgb.g .. ', ' .. rgb.b
	else
		return ""
	end
end

function p.rgbTripletToHex(frame)
	local args = frame.args or frame:getParent().args
	local r = tonumber(args[1])
	local g = tonumber(args[2])
	local b = tonumber(args [3])
	if (isempty(r) or isempty(g) or isempty(b)) then
		return ""
	else
		return rgbToHex(r,g,b)
	end
end

function p.hexToCmyk(frame)
	local args = frame.args or frame:getParent().args
	local hex = args[1]
	if (hex) then
		local p = tonumber(args.precision) or 0
		local s = args.pctsign or "1"
		local rgb = hexToRgb(hex)
		local cmyk = rgbToCmyk(rgb.r, rgb.g, rgb.b)
		local fk = formatToPrecision(cmyk.k, p)
		local fc, fm, fy
		local fracZeros = getFractionalZeros(p)
		if (fk == 100  .. fracZeros) then
			local fZero = 0 .. fracZeros
			fc = fZero
			fm = fZero
			fy = fZero
		else
			fc = formatToPrecision(cmyk.c, p)
			fm = formatToPrecision(cmyk.m, p)
			fy = formatToPrecision(cmyk.y, p)
		end
		if (s ~= "0") then
			return fc .. "%, " .. fm .. "%, " .. fy .. "%, " .. fk .. "%"
		else
			return fc .. ", " .. fm .. ", " .. fy .. ", " .. fk
		end
	else
		return ""
	end
end

function p.hexToHsl(frame)
	local args = frame.args or frame:getParent().args
	local hex = args[1]
	if (hex) then
		local p = tonumber(args.precision) or 0
		local rgb = hexToRgb(hex)
		local hsl = rgbToHsl(rgb.r, rgb.g, rgb.b)
		local fl = formatToPrecision(hsl.l, p)
		local fs, fh
		local fracZeros = getFractionalZeros(p)
		local fZero = 0 .. fracZeros
		if (fl == fZero or fl == 100 .. fracZeros) then
			fs = fZero
			fh = fZero
		else
			fs = formatToPrecision(hsl.s, p)
			if (fs == fZero) then
				fh = fZero
			else
				fh = formatToPrecision(hsl.h, p)
				if (fh == 360 .. fracZeros) then
					fh = fZero -- handle rounding to 360
				end
			end
		end
		return fh .. "°, " .. fs .. "%, " .. fl .. "%"
	else
		return ""
	end
end

function p.hexToHsv(frame)
	local args = frame.args or frame:getParent().args
	local hex = args[1]
	if (hex) then
		local p = tonumber(args.precision) or 0
		local rgb = hexToRgb(hex)
		local hsv = rgbToHsv(rgb.r, rgb.g, rgb.b)
		local fv = formatToPrecision(hsv.v, p)
		local fs, fh
		local fracZeros = getFractionalZeros(p)
		local fZero = 0 .. fracZeros
		if (fv == fZero) then
			fh = fZero
			fs = fZero
		else
			fs = formatToPrecision(hsv.s, p)
			if (fs == fZero) then
				fh = fZero
			else
				fh = formatToPrecision(hsv.h, p)
				if (fh == 360 .. fracZeros) then
					fh = fZero -- handle rounding to 360
				end
			end
		end
		return fh .. "°, " .. fs .. "%, " .. fv .. "%"
	else
		return ""
	end
end

function p.hexToCielch(frame)
	local args = frame.args or frame:getParent().args
	local hex = args[1]
	if (hex) then
		local p = tonumber(args.precision) or 0
		local rgb = hexToRgb(hex)
		local LCh = srgbToCielchuvD65o2deg(rgb.r, rgb.g, rgb.b)
		local fL = formatToPrecision(LCh.L, p)
		local fC, fh
		local fracZeros = getFractionalZeros(p)
		local fZero = 0 .. fracZeros
		if (fL == fZero or fL == 100 .. fracZeros) then
			fC = fZero
			fh = fZero
		else
			fC = formatToPrecision(LCh.C, p)
			if (fC == fZero) then
				fh = fZero
			else
				fh = formatToPrecision(LCh.h, p)
				if (fh == 360 .. fracZeros) then
					fh = fZero -- handle rounding to 360
				end
			end
		end
		return fL .. ", " .. fC .. ", " .. fh .. "°"
	else
		return ""
	end
end

function p.hexMix(frame)
	local args = frame.args or frame:getParent().args
	local hex0 = args[1]
	local hex1 = args[2]
	if (isempty(hex0) or isempty(hex1)) then
		return ""
	end
	local t = args[3]
	if (isempty(t)) then
		t = 0.5
	else
		t = tonumber(t)
		local min = tonumber(args.min) or 0
		local max = tonumber(args.max) or 100
		if (min >= max) then
			error("Minimum proportion greater than or equal to maximum")
		elseif (t < min) then
			t = 0
		elseif (t > max) then
			t = 1
		else
			t = (t - min) / (max - min)
		end
	end
	local rgb0 = hexToRgb(hex0)
	local rgb1 = hexToRgb(hex1)
	local rgb = srgbMix(t, rgb0.r, rgb0.g, rgb0.b, rgb1.r, rgb1.g, rgb1.b)
	return rgbToHex(rgb.r, rgb.g, rgb.b)
end

return p

Module:Color

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