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Speed up LMS<->XYZ conversions by a factor of 20 #48

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Speed up LMS<->XYZ conversions by a factor of 20 #48

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40 changes: 26 additions & 14 deletions src/conversions.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -14,6 +14,8 @@ function convert{T,U}(::Type{AlphaColorValue{T}}, c::AlphaColorValue{U})
AlphaColorValue{T}(convert(T, c.c), c.alpha)
end

# Temporary buffers to avoid allocations when using matrix multiplication
const tmp1, tmp2 = Array(Float64, 3), Array(Float64, 3)

# Everything to RGB
# -----------------
Expand Down Expand Up @@ -77,12 +79,12 @@ function srgb_compand(v::Float64)
v <= 0.0031308 ? 12.92v : 1.055v^(1/2.4) - 0.055
end


function convert(::Type{RGB}, c::XYZ)
ans = M_XYZ_RGB * [c.x, c.y, c.z]
correct_gamut(RGB(srgb_compand(ans[1]),
srgb_compand(ans[2]),
srgb_compand(ans[3])))
tmp1[1], tmp1[2], tmp1[3] = c.x, c.y, c.z
gemv3!(tmp2, M_XYZ_RGB, tmp1)
correct_gamut(RGB(srgb_compand(tmp2[1]),
srgb_compand(tmp2[2]),
srgb_compand(tmp2[3])))
end

convert(::Type{RGB}, c::xyY) = convert(RGB, convert(XYZ, c))
Expand Down Expand Up @@ -180,11 +182,11 @@ const M_RGB_XYZ =


function convert(::Type{XYZ}, c::RGB)
v = [invert_rgb_compand(c.r),
invert_rgb_compand(c.g),
invert_rgb_compand(c.b)]
ans = M_RGB_XYZ * v
XYZ(ans[1], ans[2], ans[3])
tmp1[1] = invert_rgb_compand(c.r)
tmp1[2] = invert_rgb_compand(c.g)
tmp1[3] = invert_rgb_compand(c.b)
gemv3!(tmp2, M_RGB_XYZ, tmp1)
XYZ(tmp2[1], tmp2[2], tmp2[3])
end


Expand Down Expand Up @@ -284,8 +286,9 @@ end


function convert(::Type{XYZ}, c::LMS)
ans = CAT02_INV * [c.l, c.m, c.s]
XYZ(ans[1], ans[2], ans[3])
tmp1[1], tmp1[2], tmp1[3] = c.l, c.m, c.s
gemv3!(tmp2, CAT02_INV, tmp1)
XYZ(tmp2[1], tmp2[2], tmp2[3])
end

# Everything to xyY
Expand Down Expand Up @@ -628,8 +631,9 @@ const CAT02_INV = inv(CAT02)


function convert(::Type{LMS}, c::XYZ)
ans = CAT02 * [c.x, c.y, c.z]
LMS(ans[1], ans[2], ans[3])
tmp1[1], tmp1[2], tmp1[3] = c.x, c.y, c.z
gemv3!(tmp2, CAT02, tmp1)
LMS(tmp2[1], tmp2[2], tmp2[3])
end


Expand All @@ -654,3 +658,11 @@ convert(::Type{Uint32}, c::RGB24) = c.color

convert(::Type{Uint32}, ac::RGBA32) = convert(Uint32, ac.c) | iround(Uint32, 255*ac.alpha)<<24

# Fast fixed-size matrix multiplication
# Copied from AffineTransforms.jl
function gemv3!(res, A, x)
@inbounds res[1] = A[1]*x[1] + A[4]*x[2] + A[7]*x[3]
@inbounds res[2] = A[2]*x[1] + A[5]*x[2] + A[8]*x[3]
@inbounds res[3] = A[3]*x[1] + A[6]*x[2] + A[9]*x[3]
res
end