Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

Make MSC & find_maximum_chroma robust to implementations of conversions #492

Merged
merged 1 commit into from
Jun 20, 2021
Merged

Make MSC & find_maximum_chroma robust to implementations of conversions #492

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
70 changes: 32 additions & 38 deletions src/algorithms.jl
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -151,6 +151,12 @@ tritanopic(c::Color) = tritanopic(c, 1.0)
# MSC - Most Saturated Colorant for given hue h
# ---------------------

const LUV_HUE_R = hue(convert(Luv, RGB(1.0, 0.0, 0.0)))
const LUV_HUE_Y = hue(convert(Luv, RGB(1.0, 1.0, 0.0)))
const LUV_HUE_G = hue(convert(Luv, RGB(0.0, 1.0, 0.0)))
const LUV_HUE_C = hue(convert(Luv, RGB(0.0, 1.0, 1.0)))
const LUV_HUE_B = hue(convert(Luv, RGB(0.0, 0.0, 1.0)))
const LUV_HUE_M = hue(convert(Luv, RGB(1.0, 0.0, 1.0)))
"""
MSC(h)
MSC(h, l; linear=false)
Expand Down Expand Up @@ -183,55 +189,42 @@ function MSC(h)
# p #variable
# o #min
# t #max
if h < 12.173988685914473 #convert(LCHuv,RGB(1,0,0)).h
p=3; t=1
elseif h < 85.872748860776770 #convert(LCHuv,RGB(1,1,0)).h
p=2; t=1
elseif h < 127.72355046632740 #convert(LCHuv,RGB(0,1,0)).h
p=1; t=2
elseif h < 192.17397321802082 #convert(LCHuv,RGB(0,1,1)).h
p=3; t=2
elseif h < 265.87273498040290 #convert(LCHuv,RGB(0,0,1)).h
p=2; t=3
elseif h < 307.72354567594960 #convert(LCHuv,RGB(1,0,1)).h
p=1; t=3
else
p=3; t=1
function pt(h)
h < LUV_HUE_R && return (3, 1)
h < LUV_HUE_Y && return (2, 1)
h < LUV_HUE_G && return (1, 2)
h < LUV_HUE_C && return (3, 2)
h < LUV_HUE_B && return (2, 3)
h < LUV_HUE_M && return (1, 3)
return (3, 1)
end
p, t = pt(h)

alpha=-sind(h)
beta=cosd(h)

#un &vn are calculated based on reference white (D65)
#X=0.95047; Y=1.0000; Z=1.08883
un = 0.19783982482140777 #4.0X/(X+15.0Y+3.0Z)
vn = 0.46833630293240970 #9.0Y/(X+15.0Y+3.0Z)
# un & vn are calculated based on reference white (D65)
un, vn = xyz_to_uv(WP_DEFAULT)

#sRGB matrix
M = [0.4124564 0.3575761 0.1804375;
0.2126729 0.7151522 0.0721750;
0.0193339 0.1191920 0.9503041]'
0.0193339 0.1191920 0.9503041]

m_tx=M[t,1]
m_ty=M[t,2]
m_tz=M[t,3]
m_px=M[p,1]
m_py=M[p,2]
m_pz=M[p,3]
m_tx, m_ty, m_tz = @view M[:, t]
m_px, m_py, m_pz = @view M[:, p]

f1 = 4alpha*m_px+9beta*m_py
a1 = 4alpha*m_tx+9beta*m_ty
f2 = m_px+15m_py+3m_pz
a2 = m_tx+15m_ty+3m_tz

cp=((alpha*un+beta*vn)*a2-a1)/(f1-(alpha*un+beta*vn)*f2)
cpc = clamp01(srgb_compand(cp))

col = zeros(3)
col[p] = clamp01(srgb_compand(cp))
# col[o] = 0.0
col[t] = 1.0
col = ntuple(i -> i == p ? cpc : Float64(i == t), Val(3))

return convert(LCHuv, RGB(col[1],col[2],col[3]))
return convert(LCHuv, RGB(col...))
end


Expand Down Expand Up @@ -262,16 +255,18 @@ function find_maximum_chroma(c::C,
mid = convert(T, (l + h) / 2)
min(mid - l, h - mid) == zero(T) && return l
lchm = C(c.l, mid, c.h)
rgbm = convert(RGB{T}, lchm)
rgbm = xyz_to_linear_rgb(convert(XYZ{T}, lchm))
clamped = max(red(rgbm), green(rgbm), blue(rgbm)) > 1-err ||
min(red(rgbm), green(rgbm), blue(rgbm)) < err
min(red(rgbm), green(rgbm), blue(rgbm)) <= 0
if clamped
return find_maximum_chroma(c, l, mid)::T
else
return find_maximum_chroma(c, mid, h)::T
end
end

const LAB_HUE_Y = hue(convert(Lab, RGB(1.0, 1.0, 0.0)))

function find_maximum_chroma(c::LCHab{T}) where T
maxc = find_maximum_chroma(c, 0, 135)

Expand All @@ -280,16 +275,15 @@ function find_maximum_chroma(c::LCHab{T}) where T
# should be modified on other conditions.
if 97 < c.h < 108 && c.l > 92
err = convert(T, 1e-6)
len = 10000
len = 100000
dh = convert(T, (100 - maxc) / len)
h_yellow = 102.85124420310268 # convert(LCHab,RGB{Float64}(1,1,0)).h
chroma = maxc
for i = 1:len
chroma += dh
rgb = convert(RGB, LCHab(c.l, chroma, c.h))
blue(rgb) < err && continue
y = c.h < h_yellow ? red(rgb) : green(rgb)
if y < 1-err
rgb = xyz_to_linear_rgb(convert(XYZ, LCHab(c.l, chroma, c.h)))
blue(rgb) < -err && continue
y = c.h < LAB_HUE_Y ? red(rgb) : green(rgb)
if y < 1+err
maxc = chroma
end
end
Expand Down
12 changes: 8 additions & 4 deletions src/conversions.jl
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -168,13 +168,17 @@ function cnvt(::Type{CV}, c::HSI) where {T, CV<:AbstractRGB{T}}
T <: FixedPoint && typemax(T) >= 1 ? CV(r % T, g % T, b % T) : CV(r, g, b)
end

function cnvt(::Type{CV}, c::XYZ) where CV<:AbstractRGB
function xyz_to_linear_rgb(c::XYZ)
r = 3.2404542*c.x - 1.5371385*c.y - 0.4985314*c.z
g = -0.9692660*c.x + 1.8760108*c.y + 0.0415560*c.z
b = 0.0556434*c.x - 0.2040259*c.y + 1.0572252*c.z
CV(clamp01(srgb_compand(r)),
clamp01(srgb_compand(g)),
clamp01(srgb_compand(b)))
RGB(r, g, b)
end
function cnvt(::Type{CV}, c::XYZ) where CV<:AbstractRGB
rgb = xyz_to_linear_rgb(c)
CV(clamp01(srgb_compand(rgb.r)),
clamp01(srgb_compand(rgb.g)),
clamp01(srgb_compand(rgb.b)))
end

function cnvt(::Type{CV}, c::YIQ) where CV<:AbstractRGB
Expand Down