Skip to content

Commit

Permalink
Clean up "src/differences.jl" (#476)
Browse files Browse the repository at this point in the history 
This exports the re-implemented version of `mean_hue`.
  • Loading branch information
@kimikage
kimikage authored May 29, 2021
1 parent 8474f07 commit 81aaf1e
Show file tree
Hide file tree
Showing 6 changed files with 103 additions and 111 deletions.
2 changes: 1 addition & 1 deletion docs/src/colordifferences.md
View file
Original file line number Diff line number Diff line change
Expand Up @@ -4,7 +4,7 @@ The [`colordiff`](@ref) function gives an approximate value for the difference b

```jldoctest example; setup = :(using Colors)
julia> colordiff(colorant"red", colorant"darkred")
23.754149863643036
23.75414986364304
julia> colordiff(colorant"red", colorant"blue")
52.88136782250768
Expand Down
1 change: 1 addition & 0 deletions docs/src/constructionandconversion.md
View file
Original file line number Diff line number Diff line change
Expand Up @@ -146,4 +146,5 @@ Depending on the source and destination colorspace, this may not be perfectly lo
parse
hex
normalize_hue
mean_hue
```
2 changes: 1 addition & 1 deletion src/Colors.jl
View file
Original file line number Diff line number Diff line change
Expand Up @@ -18,7 +18,7 @@ export weighted_color_mean,
distinguishable_colors, whitebalance,
colordiff, DE_2000, DE_94, DE_JPC79, DE_CMC, DE_BFD, DE_AB, DE_DIN99, DE_DIN99d, DE_DIN99o,
MSC, sequential_palette, diverging_palette, colormap,
normalize_hue,
normalize_hue, mean_hue,
colormatch, CIE1931_CMF, CIE1964_CMF, CIE1931J_CMF, CIE1931JV_CMF, CIE2006_2_CMF, CIE2006_10_CMF

# Early utilities
Expand Down
139 changes: 30 additions & 109 deletions src/differences.jl
View file
Original file line number Diff line number Diff line change
Expand Up @@ -151,22 +151,6 @@ Construct a metric using Euclidean color difference equation applied in the
"""
DE_DIN99o()


# Compute the mean of two hue angles
function mean_hue(h1, h2)
if abs(h2 - h1) > 180
if h1 + h2 < 360
mh = (h1 + h2 + 360) / 2
else
mh = (h1 + h2 - 360) / 2
end
else
mh = (h1 + h2) / 2
end

mh
end

# Color difference metrics
# ------------------------

Expand All @@ -181,12 +165,11 @@ end
# The CIEDE2000 color difference metric evaluated between a and b.
#

pow7(x) = (y = x*x*x; y*y*x)
pow7(x::Integer) = pow7(Float64(x))
const twentyfive7 = pow7(25)

# Delta E 2000
function _colordiff(ai::Color, bi::Color, m::DE_2000)
twentyfive7 = pow7(25)

# Ensure that the input values are in L*a*b* space
a_Lab = convert(Lab, ai)
b_Lab = convert(Lab, bi)
Expand All @@ -195,31 +178,18 @@ function _colordiff(ai::Color, bi::Color, m::DE_2000)
mc = (chroma(a_Lab) + chroma(b_Lab))/2
g = (1 - sqrt(pow7(mc) / (pow7(mc) + twentyfive7))) / 2

a_Lab_r = Lab(a_Lab.l, a_Lab.a * (1 + g), a_Lab.b)
b_Lab_r = Lab(b_Lab.l, b_Lab.a * (1 + g), b_Lab.b)

# Convert to L*C*h, where the remainder of the calculations are performed
a = convert(LCHab, Lab(a_Lab.l, a_Lab.a * (1 + g), a_Lab.b))
b = convert(LCHab, Lab(b_Lab.l, b_Lab.a * (1 + g), b_Lab.b))
a = convert(LCHab, a_Lab_r)
b = convert(LCHab, b_Lab_r)

# Calculate the delta values for each channel
dl, dc, dh = (b.l - a.l), (b.c - a.c), (b.h - a.h)
if a.c * b.c == 0
dh = zero(dh)
elseif dh > 180
dh -= 360
elseif dh < -180
dh += 360
end
# Calculate H*
dh = 2 * sqrt(a.c * b.c) * sind(dh/2)

# Calculate mean L* and C* values
ml, mc = (a.l + b.l) / 2, (a.c + b.c) / 2
dl, dc, dh = b.l - a.l, b.c - a.c, delta_h(b_Lab_r, a_Lab_r)

# Calculate mean hue value
if a.c * b.c == 0
mh = a.h + b.h
else
mh = mean_hue(a.h, b.h)
end
# Calculate mean L*, C* and hue values
ml, mc, mh = (a.l + b.l) / 2, (a.c + b.c) / 2, mean_hue(a, b)

# lightness weight
mls = (ml - 50)^2
Expand All @@ -236,9 +206,9 @@ function _colordiff(ai::Color, bi::Color, m::DE_2000)
sh = 1 + 0.015 * mc * t

# rotation term
dtheta = 30 * exp(-((mh - 275)/25)^2)
dtheta = 60 * exp(-((mh - 275)/25)^2)
cr = 2 * sqrt(pow7(mc) / (pow7(mc) + twentyfive7))
tr = -sind(2*dtheta) * cr
tr = -sind(dtheta) * cr

# Final calculation
sqrt((dl/(m.kl*sl))^2 + (dc/(m.kc*sc))^2 + (dh/(m.kh*sh))^2 +
Expand All @@ -247,59 +217,31 @@ end

# Delta E94
function _colordiff(ai::Color, bi::Color, m::DE_94)

a = convert(LCHab, ai)
b = convert(LCHab, bi)

# Calculate the delta values for each channel
dl, dc, dh = (b.l - a.l), (b.c - a.c), (b.h - a.h)
if a.c * b.c == 0
dh = zero(dh)
elseif dh > 180
dh -= 360
elseif dh < -180
dh += 360
end
# Calculate H*
dh = 2 * sqrt(a.c * b.c) * sind(dh/2)
dl, dc, dh = b.l - a.l, b.c - a.c, delta_h(b, a)

# Lightness, hue, chroma correction terms
sl = 1
sc = 1 + m.k1 * a.c
sh = 1 + m.k2 * a.c

sqrt((dl/(m.kl*sl))^2 + (dc/(m.kc*sc))^2 + (dh/(m.kh*sh))^2)

end

# Metric form of jpc79 color difference equation (mostly obsolete)
function _colordiff(ai::Color, bi::Color, m::DE_JPC79)

# Convert directly into LCh
a = convert(LCHab, ai)
b = convert(LCHab, bi)

# Calculate deltas in each direction
dl, dc, dh = (b.l - a.l), (b.c - a.c), (b.h - a.h)
if a.c * b.c == 0
dh = zero(dh)
elseif dh > 180
dh -= 360
elseif dh < -180
dh += 360
end
# Calculate H* from C*'s and h
dh = 2 * sqrt(a.c * b.c) * sind(dh/2)

#Calculate mean lightness
ml = (a.l + b.l)/2
mc = (a.c + b.c)/2
# Calculate mean hue value
if a.c * b.c == 0
mh = a.h + b.h
else
mh = mean_hue(a.h, b.h)
end
dl, dc, dh = b.l - a.l, b.c - a.c, delta_h(b, a)

# Calculate mean lightness, chroma and hue
ml, mc, mh = (a.l + b.l) / 2, (a.c + b.c) / 2, mean_hue(a, b)

# L* adjustment term
sl = 0.08195*ml/(1+0.01765*ml)
Expand All @@ -318,28 +260,17 @@ function _colordiff(ai::Color, bi::Color, m::DE_JPC79)

# Calculate the final difference
sqrt((dl/sl)^2 + (dc/sc)^2 + (dh/sh)^2)

end


# Metric form of the cmc color difference
function _colordiff(ai::Color, bi::Color, m::DE_CMC)

# Convert directly into LCh
a = convert(LCHab, ai)
b = convert(LCHab, bi)

# Calculate deltas in each direction
dl, dc, dh = (b.l - a.l), (b.c - a.c), (b.h - a.h)
if a.c * b.c == 0
dh = zero(dh)
elseif dh > 180
dh -= 360
elseif dh < -180
dh += 360
end
# Calculate H* from C*'s and h
dh = 2 * sqrt(a.c * b.c) * sind(dh/2)
dl, dc, dh = b.l - a.l, b.c - a.c, delta_h(b, a)

# L* adjustment term
if (a.l <= 16)
Expand All @@ -364,7 +295,6 @@ function _colordiff(ai::Color, bi::Color, m::DE_CMC)

# Calculate the final difference
sqrt((dl/(m.kl*sl))^2 + (dc/(m.kc*sc))^2 + (dh/sh)^2)

end

# The BFD color difference equation
Expand Down Expand Up @@ -394,36 +324,27 @@ function _colordiff(ai::Color, bi::Color, m::DE_BFD)
b = LCHab(lb, chroma(b_Lab), hue(b_Lab))

# Calculate deltas in each direction
dl, dc, dh = (b.l - a.l), (b.c - a.c), (b.h - a.h)
if a.c * b.c == 0
dh = zero(dh)
elseif dh > 180
dh -= 360
elseif dh < -180
dh += 360
end

# Calculate H* from C*'s and h
dh = 2 * sqrt(a.c * b.c) * sind(dh/2)
dl, dc, dh = b.l - a.l, b.c - a.c, delta_h(b, a)

# Find the mean value of the inputs to use as the "standard"
ml, mc = (a.l + b.l)/2, (a.c + b.c)/2

# Calculate mean hue value
if a.c * b.c == 0
mh = a.h + b.h
else
mh = mean_hue(a.h, b.h)
end
ml, mc, mh = (a.l + b.l) / 2, (a.c + b.c) / 2, mean_hue(a, b)

# Correction terms for a variety of nonlinearities in CIELAB.
g = sqrt(mc^4/(mc^4 + 14000))

t = 0.627 + 0.055*cosd(mh - 245) - 0.04*cosd(2*mh - 136) + 0.07*cosd(3*mh - 32) + 0.049*cosd(4*mh + 114) - 0.015*cosd(5*mh + 103)
t = 0.627 + 0.055 * cosd( mh - 245) -
0.040 * cosd(2mh - 136) +
0.070 * cosd(3mh - 32) +
0.049 * cosd(4mh + 114) -
0.015 * cosd(5mh + 103)

rc = sqrt(mc^6/(mc^6 + 7e7))

rh = -0.26cosd(mh-308) - 0.379cosd(2*mh-160) - 0.636*cosd(3*mh - 254) + 0.226cosd(4*mh + 140) - 0.194*cosd(5*mh + 280)
rh = -0.260 * cosd( mh - 308) -
0.379 * cosd(2mh - 160) -
0.636 * cosd(3mh - 254) +
0.226 * cosd(4mh + 140) -
0.194 * cosd(5mh + 280)

dcc = 0.035*mc/(1+0.00365*mc) + 0.521
dhh = dcc*(g*t+1-g)
Expand Down
47 changes: 47 additions & 0 deletions src/utilities.jl
View file
Original file line number Diff line number Diff line change
Expand Up @@ -26,6 +26,8 @@ pow5_12(x) = pow3_4(x) / cbrt(x) # 5/12 == 1/2 + 1/4 - 1/3 == 3/4 - 1/3
# x^y ≈ exp(y*log(x)) ≈ exp2(y*log2(y)); the middle form is faster
@noinline pow12_5(x) = x^2 * exp(0.4 * log(x)) # 12/5 == 2.4 == 2 + 0.4

pow7(x) = (y = x*x*x; y*y*x)
pow7(x::Integer) = pow7(Float64(x)) # avoid overflow

# Linear interpolation in [a, b] where x is in [0,1],
# or coerced to be if not.
Expand Down Expand Up @@ -195,6 +197,51 @@ normalize_hue(c::C) where C <: Union{LCHab, LCHuv} = C(c.l, c.c, normalize_hue(c
normalize_hue(c::C) where {Cb <: Union{LCHab, LCHuv}, C <: Union{AlphaColor{Cb}, ColorAlpha{Cb}}} =
C(c.l, c.c, normalize_hue(c.h), c.alpha)

"""
mean_hue(h1::Real, h2::Real)
mean_hue(a::C, b::C) where {C <: Colorant}
Compute the mean of two hue angles in degrees.
If the inputs are HSV-like or Lab-like color objects, this will also return a
hue, not a color. If one of the colors is achromatic, i.e. has zero saturation
or chroma, the hue of the other color is returned instead of the mean.
"""
function mean_hue(h1::T, h2::T) where {T <: Real}
@fastmath hmin, hmax = minmax(h1, h2)
d = 180 - normalize_hue(hmin - hmax - 180)
F = typeof(zero(T) / 2)
mh = muladd(F(0.5), d, hmin)
return mh < 0 ? mh + 360 : mh
end

function mean_hue(a::C, b::C) where {Cb <: Union{Lab, LCHab, Luv, LCHuv},
C <: Union{Cb, AlphaColor{Cb}, ColorAlpha{Cb}}}
h1 = chroma(a) == 0 ? hue(b) : hue(a)
h2 = chroma(b) == 0 ? hue(a) : hue(b)
mean_hue(h1, h2)
end
function mean_hue(a::C, b::C) where {Cb <: Union{HSV, HSL, HSI},
C <: Union{Cb, AlphaColor{Cb}, ColorAlpha{Cb}}}
mean_hue(a.s == 0 ? b.h : a.h, b.s == 0 ? a.h : b.h)
end
mean_hue(a, b) = mean_hue(promote(a, b)...)

function delta_h(a::C, b::C) where {Cb <: Union{Lab, Luv},
C <: Union{Cb, AlphaColor{Cb}, ColorAlpha{Cb}}}
da, db, dc = comp2(a) - comp2(b), comp3(a) - comp3(b), chroma(a) - chroma(b)
d = comp3(a) * comp2(b) - comp2(a) * comp3(b)
dh = @fastmath sqrt(max(muladd(dc, -dc, muladd(da, da, db^2)), 0))
return copysign(dh, d)
end
function delta_h(a::C, b::C) where {Cb <: Union{LCHab, LCHuv},
C <: Union{Cb, AlphaColor{Cb}, ColorAlpha{Cb}}}
sh = @fastmath (hue(a) - hue(b) + 180) / 360
d = @fastmath sh - floor(sh) - oftype(sh, 0.5)
2 * sqrt(chroma(a) * chroma(b)) * sinpi(d)
end
delta_h(a, b) = delta_h(promote(a, b)...)

"""
weighted_color_mean(w1, c1, c2)
Expand Down
23 changes: 23 additions & 0 deletions test/utilities.jl
View file
Original file line number Diff line number Diff line change
Expand Up @@ -160,6 +160,29 @@ using InteractiveUtils # for `subtypes`
@test normalize_hue(LCHuvA{Float64}(30, 40, -0.5, 0.6)) === LCHuvA{Float64}(30, 40, 359.5, 0.6)
end

@testset "mean_hue" begin
@test @inferred(mean_hue(0.0, 90.0)) === 45.0
@test @inferred(mean_hue(90.0f0, 270.0f0)) === 180.0f0
@test @inferred(mean_hue(90, 271)) === 0.5

@test @inferred(mean_hue(HSV(50, 1, 1), HSV(100, 1, 0.5))) === 75.0
@test @inferred(mean_hue(HSL(50, 1, 1), HSL(100, 0, 0.5))) === 50.0
@test @inferred(mean_hue(Lab(50, 0, 10), Lab(50, 10, -10))) === 22.5f0
@test @inferred(mean_hue(ALuv(50, 0, 0), ALuv(50, 0, 10))) === 90.0f0

@test_throws Exception mean_hue(RGB(0.1, 0.2, 0.3), RGB(0.4, 0.5, 0.6))
@test_throws Exception mean_hue(LChab(10, 20, 30), LCHuv(10, 20, 30))
end

@testset "delta_h" begin
@test @inferred(Colors.delta_h(LCHab(50, 60, 70), LCHab(90, 80, 70))) === 0.0f0
@test @inferred(Colors.delta_h(LCHuv(50, 60, 80), LCHuv(90, 0, 70))) === 0.0f0
@test @inferred(Colors.delta_h(LCHab(50, 60, 70), LCHab(90, 80, 190))) ≈ -120.0f0
@test @inferred(Colors.delta_h(LCHab(90, 80, 70), LCHab(50, 60, 310.0))) ≈ 120.0
@test @inferred(Colors.delta_h(Lab(50, -10, 10), Lab(50, 10, -10))) ≈ 28.284271f0
@test @inferred(Colors.delta_h(ALuv(50, 0, 0), ALuv(50, 0, 10))) === 0.0f0
end

# test utility function weighted_color_mean
parametric2 = [GrayA,AGray32,AGray]
parametric3 = ColorTypes.parametric3
Expand Down

0 comments on commit 81aaf1e

Please sign in to comment.