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|
if not modules then modules = { } end modules ['colo-icc'] = {
version = 1.000,
comment = "companion to colo-ini.mkiv",
author = "Hans Hagen, PRAGMA-ADE, Hasselt NL",
copyright = "PRAGMA ADE / ConTeXt Development Team",
license = "see context related readme files"
}
local char, byte, gsub, match, format, strip = string.char, string.byte, string.gsub, string.match, string.format, string.strip
local readstring, readnumber = io.readstring, io.readnumber
local band = bit32.band
local next = next
local colors = attributes and attributes.colors or { } -- when used in mtxrun
local report_colors = logs.reporter("colors","icc")
local R, Cs, lpegmatch = lpeg.R, lpeg.Cs, lpeg.match
local invalid = R(char(0)..char(31))
local cleaned = invalid^0 * Cs((1-invalid)^0)
function colors.iccprofile(filename,verbose)
local fullname = resolvers.findfile(filename,"icc") or ""
if fullname == "" then
local locate = resolvers.finders.byscheme -- not in mtxrun
if locate then
fullname = locate("loc",filename)
end
end
if fullname == "" then
report_colors("profile %a cannot be found",filename)
return nil, false
end
local f = io.open(fullname,"rb")
if not f then
report_colors("profile %a cannot be loaded",fullname)
return nil, false
end
local header = {
size = readnumber(f,4),
cmmtype = readnumber(f,4),
version = readnumber(f,4),
deviceclass = strip(readstring(f,4)),
colorspace = strip(readstring(f,4)),
connectionspace = strip(readstring(f,4)),
datetime = {
year = readnumber(f,2),
month = readnumber(f,2),
day = readnumber(f,2),
hour = readnumber(f,2),
minutes = readnumber(f,2),
seconds = readnumber(f,2),
},
filesignature = strip(readstring(f,4)),
platformsignature = strip(readstring(f,4)),
options = readnumber(f,4),
devicemanufacturer = strip(readstring(f,4)),
devicemodel = strip(readstring(f,4)),
deviceattributes = readnumber(f,4),
renderingintent = readnumber(f,4),
illuminantxyz = {
x = readnumber(f,4),
y = readnumber(f,4),
z = readnumber(f,4),
},
profilecreator = readnumber(f,4),
id = strip(readstring(f,16)),
}
local tags = { }
for i=1,readnumber(f,128,4) do
tags[readstring(f,4)] = {
offset = readnumber(f,4),
length = readnumber(f,4),
}
end
local o = header.options
header.options =
o == 0 and "embedded" or
o == 1 and "dependent" or "unknown"
local d = header.deviceattributes
header.deviceattributes = {
[band(d,1) ~= 0 and "transparency" or "reflective"] = true,
[band(d,2) ~= 0 and "mate" or "glossy" ] = true,
[band(d,3) ~= 0 and "negative" or "positive" ] = true,
[band(d,4) ~= 0 and "bw" or "color" ] = true,
}
local r = header.renderingintent
header.renderingintent =
r == 0 and "perceptual" or
r == 1 and "relative" or
r == 2 and "saturation" or
r == 3 and "absolute" or "unknown"
for tag, spec in next, tags do
if tag then
local offset, length = spec.offset, spec.length
local variant = readstring(f,offset,4)
if variant == "text" or variant == "desc" then
local str = readstring(f,length-4)
tags[tag] = {
data = str,
cleaned = lpegmatch(cleaned,str),
}
else
if verbose then
report_colors("ignoring tag %a or type %a in profile %a",tag,variant,fullname)
end
tags[tag] = nil
end
end
end
f:close()
local profile = {
filename = filename,
fullname = fullname,
header = header,
tags = tags,
}
report_colors("profile %a loaded",fullname)
return profile, true
end
-- This is just some fun stuff I decided to check out when I was making sure that
-- the 2020 metafun manual could be processed with lmtx 2021. Color conversion has
-- been part of ConTeXt from the start but it has been extended to the less commonly
-- used color spaces. We already do some CIE but didn't have lab converters to play
-- with (although I had some MetaPost done for a friend long ago). So, when we moved
-- to lmtx it made sense to also move some into the core. When searching for info
-- I ran into some formulas for lab/xyz: http://www.easyrgb.com/en/math.php and
-- http://www.brucelindbloom.com/ are useful resources. I didn't touch existing
-- code (as it works ok).
--
-- local illuminants = { -- 2=CIE 1931 10=CIE 1964
-- A = { [2] = { 109.850, 100, 35.585 }, [10] = { 111.144, 100, 35.200 } }, -- incandescent/tungsten
-- B = { [2] = { 99.093, 100, 85.313 }, [10] = { 99.178, 100, 84.349 } }, -- old direct sunlight at noon
-- C = { [2] = { 98.074, 100, 118.232 }, [10] = { 97.285, 100, 116.145 } }, -- old daylight
-- D50 = { [2] = { 96.422, 100, 82.521 }, [10] = { 96.720, 100, 81.427 } }, -- icc profile pcs
-- D55 = { [2] = { 95.682, 100, 92.149 }, [10] = { 95.799, 100, 90.926 } }, -- mid-morning daylight
-- D65 = { [2] = { 95.047, 100, 108.883 }, [10] = { 94.811, 100, 107.304 } }, -- daylight, srgb, adobe-rgb
-- D75 = { [2] = { 94.972, 100, 122.638 }, [10] = { 94.416, 100, 120.641 } }, -- north sky daylight
-- E = { [2] = { 100.000, 100, 100.000 }, [10] = { 100.000, 100, 100.000 } }, -- equal energy
-- F1 = { [2] = { 92.834, 100, 103.665 }, [10] = { 94.791, 100, 103.191 } }, -- daylight fluorescent
-- F2 = { [2] = { 99.187, 100, 67.395 }, [10] = { 103.280, 100, 69.026 } }, -- cool fluorescent
-- F3 = { [2] = { 103.754, 100, 49.861 }, [10] = { 108.968, 100, 51.965 } }, -- white fluorescent
-- F4 = { [2] = { 109.147, 100, 38.813 }, [10] = { 114.961, 100, 40.963 } }, -- warm white fluorescent
-- F5 = { [2] = { 90.872, 100, 98.723 }, [10] = { 93.369, 100, 98.636 } }, -- daylight fluorescent
-- F6 = { [2] = { 97.309, 100, 60.191 }, [10] = { 102.148, 100, 62.074 } }, -- lite white fluorescent
-- F7 = { [2] = { 95.044, 100, 108.755 }, [10] = { 95.792, 100, 107.687 } }, -- daylight fluorescent, d65 simulator
-- F8 = { [2] = { 96.413, 100, 82.333 }, [10] = { 97.115, 100, 81.135 } }, -- sylvania f40, d50 simulator
-- F9 = { [2] = { 100.365, 100, 67.868 }, [10] = { 102.116, 100, 67.826 } }, -- cool white fluorescent
-- F10 = { [2] = { 96.174, 100, 81.712 }, [10] = { 99.001, 100, 83.134 } }, -- ultralume 50, philips tl85
-- F11 = { [2] = { 100.966, 100, 64.370 }, [10] = { 103.866, 100, 65.627 } }, -- ultralume 40, philips tl84
-- F12 = { [2] = { 108.046, 100, 39.228 }, [10] = { 111.428, 100, 40.353 } }, -- ultralume 30, philips tl83
-- }
--
-- local D65 = illuminants.D65
-- local D652 = { 95.047, 100, 108.883 }
--
-- local function labref(illuminate,observer)
-- local r = illuminants[illuminant or "D65"] or D65
-- return r[observer or 2] or r[2] or D652
-- end
--
-- This is hardly useful but nice for metafun demos:
local D652 = { 95.047, 100, 108.883 }
local function xyztolab(x,y,z,mapping)
if not mapping then
mapping = D652
end
x = x / mapping[1]
y = y / mapping[2]
z = z / mapping[3]
x = (x > 0.008856) and x^(1/3) or (7.787 * x) + (16/116)
y = (y > 0.008856) and y^(1/3) or (7.787 * y) + (16/116)
z = (z > 0.008856) and z^(1/3) or (7.787 * z) + (16/116)
return
116 * y - 16,
500 * (x - y),
200 * (y - z)
end
local function labtoxyz(l,a,b,mapping)
if not mapping then
mapping = D652
end
local y = (l + 16) / 116
local x = a / 500 + y
local z = y - b / 200
return
mapping[1] * ((x^3 > 0.008856) and x^3 or (x - 16/116) / 7.787),
mapping[2] * ((y^3 > 0.008856) and y^3 or (y - 16/116) / 7.787),
mapping[3] * ((z^3 > 0.008856) and z^3 or (z - 16/116) / 7.787)
end
local function xyztorgb(x,y,z) -- D65/2°
local r = (x * 3.2404542 + y * -1.5371385 + z * -0.4985314) / 100
local g = (x * -0.9692660 + y * 1.8760108 + z * 0.0415560) / 100
local b = (x * 0.0556434 + y * -0.2040259 + z * 1.0572252) / 100
r = (r > 0.0031308) and (1.055 * r^(1/2.4) - 0.055) or (12.92 * r)
g = (g > 0.0031308) and (1.055 * g^(1/2.4) - 0.055) or (12.92 * g)
b = (b > 0.0031308) and (1.055 * b^(1/2.4) - 0.055) or (12.92 * b)
if r < 0 then r = 0 elseif r > 1 then r = 1 end
if g < 0 then g = 0 elseif g > 1 then g = 1 end
if b < 0 then b = 0 elseif b > 1 then b = 1 end
return r, g, b
end
local function rgbtoxyz(r,g,b)
r = 100 * ((r > 0.04045) and ((r + 0.055)/1.055)^2.4 or (r / 12.92))
g = 100 * ((g > 0.04045) and ((g + 0.055)/1.055)^2.4 or (g / 12.92))
b = 100 * ((b > 0.04045) and ((b + 0.055)/1.055)^2.4 or (b / 12.92))
return
r * 0.4124 + g * 0.3576 + b * 0.1805,
r * 0.2126 + g * 0.7152 + b * 0.0722,
r * 0.0193 + g * 0.1192 + b * 0.9505
end
local function labtorgb(l,a,b,mapping)
return xyztorgb(labtoxyz(l,a,b,mapping))
end
colors.xyztolab = xyztolab
colors.labtoxyz = labtoxyz
colors.xyztorgb = xyztorgb
colors.rgbtoxyz = rgbtoxyz
colors.labtorgb = labtorgb
|
