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Add temperature #34

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7 changes: 4 additions & 3 deletions src/chroma.nim
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Original file line number Diff line number Diff line change
Expand Up @@ -2,9 +2,10 @@
## **Everything you want to do with colors.**
##

import chroma/names, hashes, strutils, tables
import chroma/colortypes, chroma/distance, chroma/transformations
export colortypes, distance, transformations
import chroma/colortypes, chroma/distance, chroma/names, chroma/temperature,
chroma/transformations, hashes, strutils, tables

export colortypes, distance, temperature, transformations

proc toHex(a: float32): string {.inline.} = toHex(int(a))

Expand Down
72 changes: 72 additions & 0 deletions src/chroma/temperature.nim
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Original file line number Diff line number Diff line change
@@ -0,0 +1,72 @@
import colortypes, math

proc slopeUp(k, a, b, c, d, e: float): float =
let kp = k + e
a + b * kp.pow(3) * exp(c*kp) + d * ln(k)

proc slopeDown(k, a, b, c, d, e: float): float =
let kp = k + e
a + b * kp.pow(c) + d * ln(k)

proc fromLinear(v: float): float =
if v > 0.0031308:
((1.055 * pow(v, 1/2.4)) - 0.055)
else:
v * 12.92

proc fromTemperature*(kelvin: float): Color =
## Compute color from temperature of "ideal black-body radiator".
## Used in applications in lighting, photography, videography, publishing,
## manufacturing, astrophysics, horticulture, and other fields.
## See: https://en.wikipedia.org/wiki/Color_temperature

result.a = 1
let temperature = kelvin / 10000.0

# Calculate red
if kelvin <= 6600:
result.r = 1.0
else:
result.r = fromLinear(slopeDown(
temperature,
0.32068362618584273,
0.19668730877673762,
-1.5139012907556737,
-0.013883432789258415,
-0.21298613432655075
))

# Calculate green
if kelvin <= 6600:
result.g = fromLinear(slopeUp(
temperature,
1.226916242502167,
-1.3109482654223614,
-5.089297600846147,
0.6453936305542096,
-0.44267061967913873
))
else:
result.g = fromLinear(slopeDown(
temperature,
0.4860175851734596,
0.1802139719519286,
-1.397716496795082,
-0.00803698899233844,
-0.14573069517701578
))

# Calculate blue
if kelvin >= 6600:
result.b = 1
elif kelvin <= 1900:
result.b = 0
else:
result.b = fromLinear(slopeUp(
temperature,
1.677499032830161,
-0.02313594016938082,
-4.221279555918655,
1.6550275798913296,
-1.1367244820333684
))
260 changes: 150 additions & 110 deletions tests/test_colors.nim
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Original file line number Diff line number Diff line change
Expand Up @@ -137,154 +137,176 @@ suite "spaces":
`body`
`tmpId`

const colors = [parseHex("023FA5"),
parseHex("6371AF"),
parseHex("959CC3"),
parseHex("BEC1D4"),
parseHex("DBDCE0"),
parseHex("E0DBDC"),
parseHex("D6BCC0"),
parseHex("C6909A"),
parseHex("AE5A6D"),
parseHex("8E063B")]
const colors = [
parseHex("023FA5"),
parseHex("6371AF"),
parseHex("959CC3"),
parseHex("BEC1D4"),
parseHex("DBDCE0"),
parseHex("E0DBDC"),
parseHex("D6BCC0"),
parseHex("C6909A"),
parseHex("AE5A6D"),
parseHex("8E063B")
]
# given those colors convert to some other colorspace and compare with output
let cRgb = colors.mapIt(it.to(Color))
let expRgb = [color(0.007843137, 0.24705882, 0.6470588),
color(0.388235294, 0.44313725, 0.6862745),
color(0.584313725, 0.61176471, 0.7647059),
color(0.745098039, 0.75686275, 0.8313725),
color(0.858823529, 0.86274510, 0.8784314),
color(0.878431373, 0.85882353, 0.8627451),
color(0.839215686, 0.73725490, 0.7529412),
color(0.776470588, 0.56470588, 0.6039216),
color(0.682352941, 0.35294118, 0.4274510),
color(0.556862745, 0.02352941, 0.2313725)]
let expRgb = [
color(0.007843137, 0.24705882, 0.6470588),
color(0.388235294, 0.44313725, 0.6862745),
color(0.584313725, 0.61176471, 0.7647059),
color(0.745098039, 0.75686275, 0.8313725),
color(0.858823529, 0.86274510, 0.8784314),
color(0.878431373, 0.85882353, 0.8627451),
color(0.839215686, 0.73725490, 0.7529412),
color(0.776470588, 0.56470588, 0.6039216),
color(0.682352941, 0.35294118, 0.4274510),
color(0.556862745, 0.02352941, 0.2313725)
]
for i in 0 ..< colors.len:
check cRgb[i].almostEq(expRgb[i])

let cXyz = colors.mapIt(it.to(ColorXYZ))
let expXyz = [xyz(8.59108, 6.283171, 36.347084),
xyz(18.78561, 17.556945, 42.944822),
xyz(34.12995, 34.105738, 56.399873),
xyz(52.18543, 53.840026, 69.912376),
xyz(68.25775, 71.628143, 80.730460),
xyz(68.98728, 71.677877, 77.891637),
xyz(55.22770, 54.069481, 57.382059),
xyz(39.09464, 34.287270, 35.121978),
xyz(23.87290, 17.417248, 16.568451),
xyz(12.01096, 6.198577, 4.700508)]
let expXyz = [
xyz(8.59108, 6.283171, 36.347084),
xyz(18.78561, 17.556945, 42.944822),
xyz(34.12995, 34.105738, 56.399873),
xyz(52.18543, 53.840026, 69.912376),
xyz(68.25775, 71.628143, 80.730460),
xyz(68.98728, 71.677877, 77.891637),
xyz(55.22770, 54.069481, 57.382059),
xyz(39.09464, 34.287270, 35.121978),
xyz(23.87290, 17.417248, 16.568451),
xyz(12.01096, 6.198577, 4.700508)
]
for i in 0 ..< colors.len:
check cXyz[i].almostEq(expXyz[i])

let cLab = colors.mapIt(it.to(ColorLAB))
let expLab = [lab(30.11593, 25.6159718, -59.2291843),
lab(48.95426, 11.2745425, -34.6817925),
lab(65.04641, 6.0497111, -20.8859330),
lab(78.36836, 2.6641248, -9.8378624),
lab(87.78929, 0.3881187, -2.0712282),
lab(87.81331, 1.8741418, 0.1173351),
lab(78.50223, 9.8934416, 1.3867208),
lab(65.18995, 21.8891638, 2.8198948),
lab(48.78153, 36.2399176, 4.9170323),
lab(29.90803, 53.0297042, 8.9914552)]
let expLab = [
lab(30.11593, 25.6159718, -59.2291843),
lab(48.95426, 11.2745425, -34.6817925),
lab(65.04641, 6.0497111, -20.8859330),
lab(78.36836, 2.6641248, -9.8378624),
lab(87.78929, 0.3881187, -2.0712282),
lab(87.81331, 1.8741418, 0.1173351),
lab(78.50223, 9.8934416, 1.3867208),
lab(65.18995, 21.8891638, 2.8198948),
lab(48.78153, 36.2399176, 4.9170323),
lab(29.90803, 53.0297042, 8.9914552)
]
for i in 0 ..< colors.len:
check cLab[i].almostEq(expLab[i])

let cPolarLab = colors.mapIt(it.to(ColorPolarLab))
let expPolarLab = [polarLab(30.11593, 64.531188, 293.387952),
polarLab(48.95426, 36.468370, 288.008584),
polarLab(65.04641, 21.744452, 286.153914),
polarLab(78.36836, 10.192208, 285.152461),
polarLab(87.78929, 2.107278, 280.613332),
polarLab(87.81331, 1.877811, 3.582462),
polarLab(78.50223, 9.990154, 7.978919),
polarLab(65.18995, 22.070054, 7.340759),
polarLab(48.78153, 36.571968, 7.726709),
polarLab(29.90803, 53.786576, 9.623267)]
let expPolarLab = [
polarLab(30.11593, 64.531188, 293.387952),
polarLab(48.95426, 36.468370, 288.008584),
polarLab(65.04641, 21.744452, 286.153914),
polarLab(78.36836, 10.192208, 285.152461),
polarLab(87.78929, 2.107278, 280.613332),
polarLab(87.81331, 1.877811, 3.582462),
polarLab(78.50223, 9.990154, 7.978919),
polarLab(65.18995, 22.070054, 7.340759),
polarLab(48.78153, 36.571968, 7.726709),
polarLab(29.90803, 53.786576, 9.623267)
]
for i in 0 ..< colors.len:
check cPolarLab[i].almostEq(expPolarLab[i])

let cOklab = colors.mapIt(it.to(ColorOklab))
let expOklab = [oklab(0.6059127, -0.0618687, -0.132093335),
oklab(0.7673618, 0.0031948, -0.056107075),
oklab(0.8522680, 0.0036528, -0.029817891),
oklab(0.9129040, 0.0019834, -0.012930225),
oklab(0.9521403, 0.0002312, -0.002724297),
oklab(0.9524956, 0.0026390, 3.44801e-05),
oklab(0.9144257, 0.0145511, 0.001537969),
oklab(0.8536680, 0.0347748, 0.002470664),
oklab(0.7624759, 0.0678392, 0.001605107),
oklab(0.5607032, 0.2017071, -0.033859189)]
let expOklab = [
oklab(0.6059127, -0.0618687, -0.132093335),
oklab(0.7673618, 0.0031948, -0.056107075),
oklab(0.8522680, 0.0036528, -0.029817891),
oklab(0.9129040, 0.0019834, -0.012930225),
oklab(0.9521403, 0.0002312, -0.002724297),
oklab(0.9524956, 0.0026390, 3.44801e-05),
oklab(0.9144257, 0.0145511, 0.001537969),
oklab(0.8536680, 0.0347748, 0.002470664),
oklab(0.7624759, 0.0678392, 0.001605107),
oklab(0.5607032, 0.2017071, -0.033859189)
]
for i in 0 ..< colors.len:
check cOklab[i].almostEq(expOklab[i])

let cPolarOklab = colors.mapIt(it.to(ColorPolarOklab))
let expPolarOklab = [polarOklab(0.60591274, 0.14580541, 244.8921356),
polarOklab(0.76736181, 0.05619394, 273.2592468),
polarOklab(0.85226809, 0.03002440, 276.9880981),
polarOklab(0.91290402, 0.01315032, 278.6747741),
polarOklab(0.95214039, 0.00271021, 274.8944396),
polarOklab(0.95249563, 0.00263925, 0.7479323),
polarOklab(0.91442573, 0.01463048, 5.9677457),
polarOklab(0.85366809, 0.03486439, 4.1069898),
polarOklab(0.76247590, 0.06785918, 1.3892900),
polarOklab(0.56070321, 0.20453040, 350.4690856)]
let expPolarOklab = [
polarOklab(0.60591274, 0.14580541, 244.8921356),
polarOklab(0.76736181, 0.05619394, 273.2592468),
polarOklab(0.85226809, 0.03002440, 276.9880981),
polarOklab(0.91290402, 0.01315032, 278.6747741),
polarOklab(0.95214039, 0.00271021, 274.8944396),
polarOklab(0.95249563, 0.00263925, 0.7479323),
polarOklab(0.91442573, 0.01463048, 5.9677457),
polarOklab(0.85366809, 0.03486439, 4.1069898),
polarOklab(0.76247590, 0.06785918, 1.3892900),
polarOklab(0.56070321, 0.20453040, 350.4690856)
]
for i in 0 ..< colors.len:
check cPolarOklab[i].almostEq(expPolarOklab[i])

let cLuv = colors.mapIt(it.to(ColorLUV))
let expLuv = [luv(30.11593, -13.9580496, -78.86780920),
luv(48.95426, -9.5461094, -53.36486065),
luv(65.04641, -5.8182031, -32.96385756),
luv(78.36836, -2.7172101, -15.56125899),
luv(87.78929, -0.7842912, -3.24049702),
luv(87.81331, 2.7833622, -0.15499877),
luv(78.50223, 15.2042643, 0.29225224),
luv(65.18995, 33.5088794, 0.07679983),
luv(48.78153, 55.3929249, -0.11567890),
luv(29.90803, 79.9308245, 0.04076898)]
let expLuv = [
luv(30.11593, -13.9580496, -78.86780920),
luv(48.95426, -9.5461094, -53.36486065),
luv(65.04641, -5.8182031, -32.96385756),
luv(78.36836, -2.7172101, -15.56125899),
luv(87.78929, -0.7842912, -3.24049702),
luv(87.81331, 2.7833622, -0.15499877),
luv(78.50223, 15.2042643, 0.29225224),
luv(65.18995, 33.5088794, 0.07679983),
luv(48.78153, 55.3929249, -0.11567890),
luv(29.90803, 79.9308245, 0.04076898)
]
for i in 0 ..< colors.len:
check cLuv[i].almostEq(expLuv[i])

let cPolarLuv = colors.mapIt(it.to(ColorPolarLuv))
let expPolarLuv = [polarLuv(259.9636996, 80.093436, 30.11593),
polarLuv(259.8579844, 54.211960, 48.95426),
polarLuv(259.9902473, 33.473383, 65.04641),
polarLuv(260.0952278, 15.796709, 78.36836),
polarLuv(256.3944472, 3.3340570, 87.78929),
polarLuv(356.8126275, 2.7876750, 87.81331),
polarLuv(1.101188300, 15.207073, 78.50223),
polarLuv(0.131317400, 33.508967, 65.18995),
polarLuv(359.8803475, 55.393046, 48.78153),
polarLuv(0.029223900, 79.930835, 29.90803)]
let expPolarLuv = [
polarLuv(259.9636996, 80.093436, 30.11593),
polarLuv(259.8579844, 54.211960, 48.95426),
polarLuv(259.9902473, 33.473383, 65.04641),
polarLuv(260.0952278, 15.796709, 78.36836),
polarLuv(256.3944472, 3.3340570, 87.78929),
polarLuv(356.8126275, 2.7876750, 87.81331),
polarLuv(1.101188300, 15.207073, 78.50223),
polarLuv(0.131317400, 33.508967, 65.18995),
polarLuv(359.8803475, 55.393046, 48.78153),
polarLuv(0.029223900, 79.930835, 29.90803)
]
for i in 0 ..< colors.len:
check cPolarLuv[i].almostEq(expPolarLuv[i])

let cHsl = colors.mapIt(it.to(ColorHsl))
let expHsl = [hsl(217.5460, 97.604790, 32.74510),
hsl(228.9474, 32.203390, 53.72549),
hsl(230.8696, 27.710843, 67.45098),
hsl(231.8182, 20.370370, 78.82353),
hsl(228.0000, 07.462687, 86.86275),
hsl(348.0000, 07.462687, 86.86275),
hsl(350.7692, 24.074074, 78.82353),
hsl(348.8889, 32.142857, 67.05882),
hsl(346.4286, 34.146341, 51.76471),
hsl(336.6176, 91.891892, 29.01961)]
let expHsl = [
hsl(217.5460, 97.604790, 32.74510),
hsl(228.9474, 32.203390, 53.72549),
hsl(230.8696, 27.710843, 67.45098),
hsl(231.8182, 20.370370, 78.82353),
hsl(228.0000, 07.462687, 86.86275),
hsl(348.0000, 07.462687, 86.86275),
hsl(350.7692, 24.074074, 78.82353),
hsl(348.8889, 32.142857, 67.05882),
hsl(346.4286, 34.146341, 51.76471),
hsl(336.6176, 91.891892, 29.01961)
]
for i in 0 ..< colors.len:
check cHsl[i].almostEq(expHsl[i])

let cHsv = colors.mapIt(it.to(ColorHsv))
let expHsv = [hsv(217.5460, 98.787879, 64.70588),
hsv(228.9474, 43.428571, 68.62745),
hsv(230.8696, 23.589744, 76.47059),
hsv(231.8182, 10.377358, 83.13725),
hsv(228.0000, 02.232143, 87.84314),
hsv(348.0000, 02.232143, 87.84314),
hsv(350.7692, 12.149533, 83.92157),
hsv(348.8889, 27.272727, 77.64706),
hsv(346.4286, 48.275862, 68.23529),
hsv(336.6176, 95.774648, 55.68627)]
let expHsv = [
hsv(217.5460, 98.787879, 64.70588),
hsv(228.9474, 43.428571, 68.62745),
hsv(230.8696, 23.589744, 76.47059),
hsv(231.8182, 10.377358, 83.13725),
hsv(228.0000, 02.232143, 87.84314),
hsv(348.0000, 02.232143, 87.84314),
hsv(350.7692, 12.149533, 83.92157),
hsv(348.8889, 27.272727, 77.64706),
hsv(346.4286, 48.275862, 68.23529),
hsv(336.6176, 95.774648, 55.68627)
]
for i in 0 ..< colors.len:
check cHsv[i].almostEq(expHsv[i])

Expand Down Expand Up @@ -357,6 +379,24 @@ suite "distance":
result = distance(c1, c2) / 100
check result < 0.05 # proximity threshold set in linguist

suite "temperature":
test "compute":
doAssert fromTemperature(1700).almostEqual(color(1.0, 0.4728460609912872, 0.0, 1.0)) # Match flame, low pressure sodium lamps (LPS/SOX)
doAssert fromTemperature(1850).almostEqual(color(1.0, 0.5075678825378418, 0.0, 1.0)) # Candle flame, sunset/sunrise
doAssert fromTemperature(2400).almostEqual(color(1.0, 0.6151175498962402, 0.2489356100559235, 1.0)) # Standard incandescent lamps
doAssert fromTemperature(2550).almostEqual(color(1.0, 0.640208899974823, 0.2967877089977264, 1.0)) # Soft white incandescent lamps
doAssert fromTemperature(2700).almostEqual(color(1.0, 0.6637818813323975, 0.3408890664577484, 1.0)) # "Soft white" compact fluorescent and LED lamps
doAssert fromTemperature(3000).almostEqual(color(1.0, 0.7068109512329102, 0.4213423728942871, 1.0)) # Warm white compact fluorescent and LED lamps
doAssert fromTemperature(3200).almostEqual(color(1.0, 0.7327497601509094, 0.4705604314804077, 1.0)) # Studio lamps, photofloods, etc.
doAssert fromTemperature(3350).almostEqual(color(1.0, 0.7509022951126099, 0.5055340528488159, 1.0)) # Studio "CP" light
doAssert fromTemperature(5000).almostEqual(color(1.0, 0.8959282636642456, 0.8083687424659729, 1.0)) # Horizon daylight
doAssert fromTemperature(5000).almostEqual(color(1.0, 0.8959282636642456, 0.8083687424659729, 1.0)) # Tubular fluorescent lamps or cool white
doAssert fromTemperature(5500).almostEqual(color(1.0, 0.9261417388916016, 0.8775315284729004, 1.0)) # Vertical daylight, electronic flash
doAssert fromTemperature(6200).almostEqual(color(1.0, 0.9618642926216126, 0.9614840745925903, 1.0)) # Xenon short-arc lamp [2]
doAssert fromTemperature(6500).almostEqual(color(1.0, 0.9753435850143433, 0.9935365319252014, 1.0)) # Daylight, overcast
doAssert fromTemperature(6500).almostEqual(color(1.0, 0.9753435850143433, 0.9935365319252014, 1.0)) # LCD or CRT screen
doAssert fromTemperature(15000).almostEqual(color(0.7009154558181763, 0.7981580495834351, 1.0, 1.0)) # Clear blue poleward sky

when false:
# example in readme:
import chroma
Expand Down