Merge pull request #39 from edisile/patch-1

Fix Oklab inverse transform and update matrices
treeform · Feb 2, 2023 · 64eab23 · 64eab23
2 parents 149d62b + f5b64a8
commit 64eab23
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diff --git a/src/chroma/transformations.nim b/src/chroma/transformations.nim
@@ -530,25 +530,28 @@ proc color*(c: ColorPolarLUV): Color {.inline.} =
 proc oklab*(c: Color): ColorOklab {.inline.} =
   ## convert Color to ColorOklab
   let
-    l = cbrt(0.4121656120f * c.r + 0.5362752080f * c.g + 0.0514575653f * c.b)
-    m = cbrt(0.2118591070f * c.r + 0.6807189584f * c.g + 0.1074065790f * c.b)
-    s = cbrt(0.0883097947f * c.r + 0.2818474174f * c.g + 0.6302613616f * c.b)
-  result.L = 0.2104542553f*l + 0.7936177850f*m - 0.0040720468f*s
-  result.a = 1.9779984951f*l - 2.4285922050f*m + 0.4505937099f*s
-  result.b = 0.0259040371f*l + 0.7827717662f*m - 0.8086757660f*s
+    r = ftrans(c.r, 2.4)
+    g = ftrans(c.g, 2.4)
+    b = ftrans(c.b, 2.4)
+    l = cbrt(0.4122214708f * r + 0.5363325363f * g + 0.0514459929f * b)
+    m = cbrt(0.2119034982f * r + 0.6806995451f * g + 0.1073969566f * b)
+    s = cbrt(0.0883024619f * r + 0.2817188376f * g + 0.6299787005f * b)
+  result.L = 0.2104542553f * l + 0.7936177850f * m - 0.0040720468f * s
+  result.a = 1.9779984951f * l - 2.4285922050f * m + 0.4505937099f * s
+  result.b = 0.0259040371f * l + 0.7827717662f * m - 0.8086757660f * s
 
 proc color*(c: ColorOklab): Color {.inline.} =
   ## convert ColorOklab to Color
   let
     l = c.L + 0.3963377774f * c.a + 0.2158037573f * c.b
     m = c.L - 0.1055613458f * c.a - 0.0638541728f * c.b
     s = c.L - 0.0894841775f * c.a - 1.2914855480f * c.b
-    l3 = l*l*l
-    m3 = m*m*m
-    s3 = s*s*s
-  result.r = + 4.0767245293f*l - 3.3072168827f*m + 0.2307590544f*s
-  result.g = - 1.2681437731f*l + 2.6093323231f*m - 0.3411344290f*s
-  result.b = - 0.0041119885f*l - 0.7034763098f*m + 1.7068625689f*s
+    l3 = l * l * l
+    m3 = m * m * m
+    s3 = s * s * s
+  result.r = gtrans(+4.0767416621f * l3 - 3.3077115913f * m3 + 0.2309699292f * s3)
+  result.g = gtrans(-1.2684380046f * l3 + 2.6097574011f * m3 - 0.3413193965f * s3)
+  result.b = gtrans(-0.0041960863f * l3 - 0.7034186147f * m3 + 1.7076147010f * s3)
   result.a = 1.0
 
 proc oklab*(c: ColorPolarOklab): ColorOklab {.inline.} =

diff --git a/tests/test_colors.nim b/tests/test_colors.nim
@@ -216,32 +216,32 @@ suite "spaces":
 
     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)
+      oklab(0.40672997, -0.02695328, -0.17169085),
+      oklab(0.56404305,  0.00549200, -0.09741843),
+      oklab(0.70085692,  0.00688213, -0.05724370),
+      oklab(0.81447536,  0.00402534, -0.02647555),
+      oklab(0.89487135,  0.00047883, -0.00551909),
+      oklab(0.89565080,  0.00560808,  0.00032860),
+      oklab(0.81843138,  0.02985227,  0.00379938),
+      oklab(0.70829993,  0.06616995,  0.00769448),
+      oklab(0.57255679,  0.11003068,  0.01315761),
+      oklab(0.41695607,  0.16161427,  0.02273411)
     ]
     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)
+      polarOklab(0.40672997, 0.17379364, 261.07812500),
+      polarOklab(0.56404305, 0.09757311, 273.22665405),
+      polarOklab(0.70085692, 0.05765592, 276.85546875),
+      polarOklab(0.81447536, 0.02677981, 278.64501953),
+      polarOklab(0.89487135, 0.00553983, 274.95852661),
+      polarOklab(0.89565080, 0.00561770,   3.35335946),
+      polarOklab(0.81843138, 0.03009308,   7.25319290),
+      polarOklab(0.70829993, 0.06661581,   6.63277388),
+      polarOklab(0.57255679, 0.11081459,   6.81911993),
+      polarOklab(0.41695607, 0.16320543,   8.00719738)
     ]
     for i in 0 ..< colors.len:
       check cPolarOklab[i].almostEq(expPolarOklab[i])