Wavelength-sampled chromatic aberration for Nuke—radial, linear, or spin CA from dispersion curves, not RGB channel scale.
Spectral Aberration builds chromatic aberration by sampling wavelengths across a range and reconstructing RGB with CIE-based weights. It is not a simple RGB channel scale or offset.
Use it to match plate lens CA or add controlled fringing. Mode covers radial (lateral CA), linear (prism smear), spin (Helios-style swirl), and radial then spin. Dispersion options are linear wavelength, BK7 Cauchy, and flint SF10. Amount sets strength; protect and falloff keep the center clean. Focus wavelength, lambda min/max, samples, fringe saturation, aspect, invert, and center shape the fringe.
Alpha can stay on the source or dilate to the fringe. Overscan, preserve bbox, mask, and mix fit standard comp use. The effect runs on BlinkScript and needs commercial Nuke; bind knobs after a kernel recompile if controls do not drive.
set cut_paste_input [stack 0]
version 17.0 v3
push $cut_paste_input
Group {
name spectralAberration
help "spectralAberration v1.2\n\nWavelength-sampled CA. Not RGB channel scale.\n\nIf the Viewer looks unchanged:\n1. Ctrl+Enter into this Group\n2. Select SpectralCA_kernel\n3. BlinkScript tab → factory Recompile\n4. Click Bind knobs on this Group\n5. Set amount to 0.05 and protect to 0. Look at the corners.\n\nBlinkScript requires commercial Nuke.\nderekvfx.ca"
onCreate "n = nuke.thisNode()\nk = n.node('SpectralCA_kernel')\nif k is not None:\n try:\n src = k\['kernelSource'].value()\n k\['kernelSource'].setValue(src)\n except Exception:\n pass\n try:\n if 'rebuild' in k.knobs():\n k\['rebuild'].setValue('')\n except Exception:\n pass\n pairs = \[\n ('SpectralCA_amount', 'parent.amount'),\n ('SpectralCA_samples', 'parent.samples'),\n ('SpectralCA_focusNm', 'parent.focusNm'),\n ('SpectralCA_lambdaMin', 'parent.lambdaMin'),\n ('SpectralCA_lambdaMax', 'parent.lambdaMax'),\n ('SpectralCA_mode', 'parent.mode'),\n ('SpectralCA_curve', 'parent.curve'),\n ('SpectralCA_invert', 'parent.invert'),\n ('SpectralCA_alphaMode', 'parent.alphaMode'),\n ('SpectralCA_aspect', 'parent.aspect'),\n ('SpectralCA_protect', 'parent.protect'),\n ('SpectralCA_falloff', 'parent.falloff'),\n ('SpectralCA_angleDeg', 'parent.angleDeg'),\n ('SpectralCA_spinDeg', 'parent.spinDeg'),\n ('SpectralCA_fringeSat', 'parent.fringeSat'),\n ]\n for knob, expr in pairs:\n if k.knob(knob):\n try:\n k\[knob].setExpression(expr)\n except Exception:\n pass\n if k.knob('SpectralCA_center'):\n try:\n k\['SpectralCA_center'].setExpression('parent.center.x', 0)\n k\['SpectralCA_center'].setExpression('parent.center.y', 1)\n except Exception:\n pass\n if k.knob('SpectralCA_formatSize'):\n try:\n k\['SpectralCA_formatSize'].setExpression('width', 0)\n k\['SpectralCA_formatSize'].setExpression('height', 1)\n except Exception:\n pass\n"
tile_color 0x421010ff
label "spectral CA"
selected true
xpos 507
ypos 971
addUserKnob {20 User l spectralAberration}
addUserKnob {22 bindBtn l "Bind knobs" t "Wire Group knobs to the inner Blink kernel. Does not call execute() on PythonKnobs. If it says 0 knobs bound, use the factory Recompile inside SpectralCA_kernel first." -STARTLINE T "n = nuke.thisNode()\nk = n.node('SpectralCA_kernel')\nif k is None:\n nuke.message('SpectralCA_kernel not found. Ctrl+Enter into the Group and check.')\nelse:\n try:\n src = k\['kernelSource'].value()\n k\['kernelSource'].setValue(src)\n except Exception:\n pass\n try:\n if 'rebuild' in k.knobs():\n k\['rebuild'].setValue('')\n except Exception:\n pass\n try:\n if 'recompileCount' in k.knobs():\n k\['recompileCount'].setValue(int(k\['recompileCount'].value()) + 1)\n except Exception:\n pass\n pairs = \[\n ('SpectralCA_amount', 'parent.amount'),\n ('SpectralCA_samples', 'parent.samples'),\n ('SpectralCA_focusNm', 'parent.focusNm'),\n ('SpectralCA_lambdaMin', 'parent.lambdaMin'),\n ('SpectralCA_lambdaMax', 'parent.lambdaMax'),\n ('SpectralCA_mode', 'parent.mode'),\n ('SpectralCA_curve', 'parent.curve'),\n ('SpectralCA_invert', 'parent.invert'),\n ('SpectralCA_alphaMode', 'parent.alphaMode'),\n ('SpectralCA_aspect', 'parent.aspect'),\n ('SpectralCA_protect', 'parent.protect'),\n ('SpectralCA_falloff', 'parent.falloff'),\n ('SpectralCA_angleDeg', 'parent.angleDeg'),\n ('SpectralCA_spinDeg', 'parent.spinDeg'),\n ('SpectralCA_fringeSat', 'parent.fringeSat'),\n ]\n bound = 0\n missing = \[]\n for knob, expr in pairs:\n if k.knob(knob):\n try:\n k\[knob].setExpression(expr)\n bound += 1\n except Exception:\n missing.append(knob)\n else:\n missing.append(knob)\n if k.knob('SpectralCA_center'):\n try:\n k\['SpectralCA_center'].setExpression('parent.center.x', 0)\n k\['SpectralCA_center'].setExpression('parent.center.y', 1)\n bound += 1\n except Exception:\n missing.append('SpectralCA_center')\n else:\n missing.append('SpectralCA_center')\n if k.knob('SpectralCA_formatSize'):\n try:\n k\['SpectralCA_formatSize'].setExpression('width', 0)\n k\['SpectralCA_formatSize'].setExpression('height', 1)\n bound += 1\n except Exception:\n missing.append('SpectralCA_formatSize')\n else:\n missing.append('SpectralCA_formatSize')\n if bound == 0:\n nuke.message('Kernel params are not built yet.\\n\\nCtrl+Enter into the Group, select SpectralCA_kernel, open the BlinkScript tab, click the factory Recompile button, then click Bind knobs again.\\n\\nOr just drive amount on the Kernel Parameters tab (try 0.05, protect 0).')\n else:\n nuke.message('Bound %d kernel knobs.\\nSet amount to 0.05 and protect to 0, then look at the frame corners.' % bound)\n"}
addUserKnob {26 ""}
addUserKnob {4 mode t "radial = lateral CA.\nlinear = prism smear.\nspin = Helios swirl.\nradial+spin = radial then swirl." M {radial linear spin radial+spin}}
addUserKnob {4 curve l dispersion t "linear λ = even hues.\nBK7 Cauchy = crown glass.\nflint SF10 = heavier blue." M {"linear λ" "BK7 Cauchy" "flint SF10"}}
curve "flint SF10"
addUserKnob {7 amount t "0.05 is obvious. 0.008-0.02 matches plates. 0 is identity." R -0.2 0.2}
amount 0.022
addUserKnob {3 samples}
samples 22
addUserKnob {6 invert t "Flip red/blue sides." -STARTLINE}
addUserKnob {26 ""}
addUserKnob {7 focusNm l "focus (nm)" R 400 700}
focusNm 550
addUserKnob {7 lambdaMin l "λ min" R 380 500}
lambdaMin 400
addUserKnob {7 lambdaMax l "λ max" R 600 780}
lambdaMax 700
addUserKnob {7 fringeSat l "fringe sat" R 0 2}
fringeSat 1
addUserKnob {26 ""}
addUserKnob {12 center}
center {{width/2} {height/2}}
addUserKnob {22 snapCenter l "snap / lock center" -STARTLINE T "n = nuke.thisNode()\nn\['center'].clearAnimated()\nn\['center'].setExpression('width/2', 0)\nn\['center'].setExpression('height/2', 1)\n"}
addUserKnob {22 unlockCenter l unlock -STARTLINE T "n = nuke.thisNode()\ntry:\n x = n.width()/2.0\n y = n.height()/2.0\nexcept:\n x = n\['center'].getValue(0)\n y = n\['center'].getValue(1)\nn\['center'].clearAnimated()\nn\['center'].setValue(\[x, y])\n"}
addUserKnob {7 aspect R 0.25 4}
aspect 1
addUserKnob {7 protect t "0 = aberration everywhere. 0.2 = clean center."}
addUserKnob {7 falloff l "protect gamma" R 0.1 4}
falloff 1
addUserKnob {26 ""}
addUserKnob {7 spinDeg l swirl R -45 45}
addUserKnob {7 angleDeg l "linear angle" R -180 180}
addUserKnob {26 ""}
addUserKnob {4 alphaMode l alpha M {"source alpha" "dilate to fringe"}}
addUserKnob {7 overscan R 0 200}
overscan 32
addUserKnob {6 preserveBBox l "preserve bbox" +STARTLINE}
preserveBBox true
addUserKnob {26 ""}
addUserKnob {41 maskChannelMask l mask T MergeOut.maskChannelMask}
addUserKnob {41 invert_mask l invert T MergeOut.invert_mask}
addUserKnob {41 mix T MergeOut.mix}
addUserKnob {26 ""}
addUserKnob {26 lbl l "" +STARTLINE T "spectralAberration v1.2"}
addUserKnob {22 btn l DerekVFX.ca T "nuke.tcl('start', 'https://derekvfx.ca')" +STARTLINE}
}
Input {
inputs 0
name Input
xpos 0
ypos -400
}
set Nd44d4f00 [stack 0]
Input {
inputs 0
name mask
xpos 280
ypos -400
number 1
}
AddChannels {
channels rgba
name AddChannels1
xpos 280
ypos -376
}
push $Nd44d4f00
push $Nd44d4f00
AdjBBox {
numpixels {{parent.overscan}}
name AdjBBox1
xpos 0
ypos -300
}
BlinkScript {
recompileCount 2
ProgramGroup 1
KernelDescription "3 \"SpectralCA\" iterate pixelWise b3cabcc9dea6241db8efaa5ebee73a76791c436fdfcf30f63f6d4d77719a322d 2 \"src\" Read Random \"dst\" Write Point 17 \"amount\" Float 1 CtcjPQ== \"samples\" Int 1 CwAAAA== \"focusNm\" Float 1 AIAJRA== \"lambdaMin\" Float 1 AADIQw== \"lambdaMax\" Float 1 AAAvRA== \"mode\" Int 1 AAAAAA== \"curve\" Int 1 AQAAAA== \"invert\" Int 1 AAAAAA== \"alphaMode\" Int 1 AAAAAA== \"center\" Float 2 AABwRAAAB0Q= \"formatSize\" Float 2 AADwRAAAh0Q= \"aspect\" Float 1 AACAPw== \"protect\" Float 1 zcxMPg== \"falloff\" Float 1 AACAPw== \"angleDeg\" Float 1 AAAAAA== \"spinDeg\" Float 1 AAAAAA== \"fringeSat\" Float 1 AACAPw== 17 \"amount\" 1 1 Default \"samples\" 1 1 Default \"focusNm\" 1 1 Default \"lambdaMin\" 1 1 Default \"lambdaMax\" 1 1 Default \"mode\" 1 1 Default \"curve\" 1 1 Default \"invert\" 1 1 Default \"alphaMode\" 1 1 Default \"center\" 2 1 Default \"formatSize\" 2 1 Default \"aspect\" 1 1 Default \"protect\" 1 1 Default \"falloff\" 1 1 Default \"angleDeg\" 1 1 Default \"spinDeg\" 1 1 Default \"fringeSat\" 1 1 Default 4 \"wRGB\" Float 3 32 AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA= \"disp\" Float 1 32 AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA= \"n\" Int 1 1 AAAAAA== \"maxRadius\" Float 1 1 AAAAAA=="
kernelSource "kernel SpectralCA : ImageComputationKernel<ePixelWise>\n\{\n Image<eRead, eAccessRandom, eEdgeClamped> src;\n Image<eWrite> dst;\n\n param:\n float amount;\n int samples;\n float focusNm;\n float lambdaMin;\n float lambdaMax;\n int mode;\n int curve;\n int invert;\n int alphaMode;\n float2 center;\n float2 formatSize;\n float aspect;\n float protect;\n float falloff;\n float angleDeg;\n float spinDeg;\n float fringeSat;\n\n local:\n float3 wRGB\[32];\n float disp\[32];\n int n;\n float maxRadius;\n\n void define() \{\n defineParam(amount, \"amount\", 0.04f);\n defineParam(samples, \"samples\", 11);\n defineParam(focusNm, \"focusNm\", 550.0f);\n defineParam(lambdaMin, \"lambdaMin\", 400.0f);\n defineParam(lambdaMax, \"lambdaMax\", 700.0f);\n defineParam(mode, \"mode\", 0);\n defineParam(curve, \"curve\", 1);\n defineParam(invert, \"invert\", 0);\n defineParam(alphaMode, \"alphaMode\", 0);\n defineParam(center, \"center\", float2(960.0f, 540.0f));\n defineParam(formatSize, \"formatSize\", float2(1920.0f, 1080.0f));\n defineParam(aspect, \"aspect\", 1.0f);\n defineParam(protect, \"protect\", 0.2f);\n defineParam(falloff, \"falloff\", 1.0f);\n defineParam(angleDeg, \"angleDeg\", 0.0f);\n defineParam(spinDeg, \"spinDeg\", 0.0f);\n defineParam(fringeSat, \"fringeSat\", 1.0f);\n \}\n\n float cmfX(float lam) \{\n float t1 = (lam - 442.0f) * ((lam < 442.0f) ? 0.0624f : 0.0374f);\n float t2 = (lam - 599.8f) * ((lam < 599.8f) ? 0.0264f : 0.0323f);\n float t3 = (lam - 501.1f) * ((lam < 501.1f) ? 0.0490f : 0.0382f);\n return 0.362f * exp(-0.5f * t1 * t1)\n + 1.056f * exp(-0.5f * t2 * t2)\n - 0.065f * exp(-0.5f * t3 * t3);\n \}\n\n float cmfY(float lam) \{\n float t1 = (lam - 568.8f) * ((lam < 568.8f) ? 0.0213f : 0.0247f);\n float t2 = (lam - 530.9f) * ((lam < 530.9f) ? 0.0613f : 0.0322f);\n return 0.821f * exp(-0.5f * t1 * t1)\n + 0.286f * exp(-0.5f * t2 * t2);\n \}\n\n float cmfZ(float lam) \{\n float t1 = (lam - 437.0f) * ((lam < 437.0f) ? 0.0845f : 0.0278f);\n float t2 = (lam - 459.0f) * ((lam < 459.0f) ? 0.0385f : 0.0725f);\n return 1.217f * exp(-0.5f * t1 * t1)\n + 0.681f * exp(-0.5f * t2 * t2);\n \}\n\n float3 xyzToRec709(float3 xyz) \{\n return float3(\n 3.2404542f * xyz.x - 1.5371385f * xyz.y - 0.4985314f * xyz.z,\n -0.9692660f * xyz.x + 1.8760108f * xyz.y + 0.0415560f * xyz.z,\n 0.0556434f * xyz.x - 0.2040259f * xyz.y + 1.0572252f * xyz.z\n );\n \}\n\n float iorDelta(float lamNm, float focus) \{\n if (curve == 0) \{\n return (focus - lamNm) / max(lambdaMax - lambdaMin, 1.0f);\n \}\n float u = lamNm * 0.001f;\n float uf = focus * 0.001f;\n float B = (curve == 2) ? 0.01342f : 0.00420f;\n return (B / max(u * u, 1.0e-8f)) - (B / max(uf * uf, 1.0e-8f));\n \}\n\n float smstep(float e0, float e1, float x) \{\n float t = clamp((x - e0) / max(e1 - e0, 1.0e-8f), 0.0f, 1.0f);\n return t * t * (3.0f - 2.0f * t);\n \}\n\n void init() \{\n n = samples;\n if (n < 3) n = 3;\n if (n > 32) n = 32;\n\n float l0 = min(lambdaMin, lambdaMax);\n float l1 = max(lambdaMin, lambdaMax);\n if (l1 - l0 < 1.0f) l1 = l0 + 1.0f;\n float focus = clamp(focusNm, l0, l1);\n\n float sign = (invert != 0) ? -1.0f : 1.0f;\n float maxAbs = 1.0e-4f;\n int i;\n for (i = 0; i < 32; i++) \{\n wRGB\[i] = float3(0.0f, 0.0f, 0.0f);\n disp\[i] = 0.0f;\n if (i < n) \{\n float t = (n > 1) ? float(i) / float(n - 1) : 0.5f;\n float lam = l0 + t * (l1 - l0);\n float d = iorDelta(lam, focus);\n disp\[i] = d;\n float ad = fabs(d);\n if (ad > maxAbs) maxAbs = ad;\n \}\n \}\n\n float3 sumW = float3(0.0f, 0.0f, 0.0f);\n for (i = 0; i < 32; i++) \{\n if (i < n) \{\n float t = (n > 1) ? float(i) / float(n - 1) : 0.5f;\n float lam = l0 + t * (l1 - l0);\n disp\[i] = (disp\[i] / maxAbs) * sign;\n\n float3 xyz = float3(cmfX(lam), cmfY(lam), cmfZ(lam));\n float3 rgb = xyzToRec709(xyz);\n rgb = float3(max(rgb.x, 0.0f), max(rgb.y, 0.0f), max(rgb.z, 0.0f));\n float lum = (rgb.x + rgb.y + rgb.z) * 0.33333334f;\n float sat = clamp(fringeSat, 0.0f, 2.0f);\n rgb = float3(\n lum + (rgb.x - lum) * sat,\n lum + (rgb.y - lum) * sat,\n lum + (rgb.z - lum) * sat\n );\n wRGB\[i] = rgb;\n sumW += rgb;\n \}\n \}\n\n sumW = float3(max(sumW.x, 1.0e-8f), max(sumW.y, 1.0e-8f), max(sumW.z, 1.0e-8f));\n for (i = 0; i < 32; i++) \{\n if (i < n) \{\n wRGB\[i] = float3(wRGB\[i].x / sumW.x, wRGB\[i].y / sumW.y, wRGB\[i].z / sumW.z);\n \}\n \}\n\n float2 fs = formatSize;\n if (fs.x < 1.0f) fs.x = 1.0f;\n if (fs.y < 1.0f) fs.y = 1.0f;\n float asp = (aspect <= 0.0f) ? 1.0f : aspect;\n maxRadius = 0.5f * length(float2(fs.x, fs.y * asp));\n if (maxRadius < 1.0f) maxRadius = 1.0f;\n \}\n\n void process(int2 pos) \{\n float2 p = float2(float(pos.x) + 0.5f, float(pos.y) + 0.5f);\n SampleType(src) srcCol = bilinear(src, p.x, p.y);\n\n float2 c = center;\n float asp = (aspect <= 0.0f) ? 1.0f : aspect;\n float2 v = p - c;\n v.y *= asp;\n float rNorm = length(v) / maxRadius;\n\n float fade = 1.0f;\n if (protect >= 0.999f) \{\n fade = 0.0f;\n \} else if (protect > 0.0f) \{\n fade = smstep(protect, 1.0f, rNorm);\n fade = pow(max(fade, 0.0f), max(falloff, 0.01f));\n \}\n\n float amountEff = amount * fade;\n if (fabs(amountEff) < 1.0e-8f) \{\n dst() = srcCol;\n return;\n \}\n\n float ang = angleDeg * 0.017453292519943295f;\n float2 dirLin = float2(cos(ang), sin(ang));\n float spinMax = spinDeg * 0.017453292519943295f;\n\n float3 acc = float3(0.0f, 0.0f, 0.0f);\n float aMax = srcCol.w;\n\n int i;\n for (i = 0; i < 32; i++) \{\n if (i < n) \{\n float d = disp\[i] * amountEff;\n float2 dir = v;\n\n if (mode == 2 || mode == 3) \{\n float th = spinMax * disp\[i] * fade;\n float cs = cos(th);\n float sn = sin(th);\n dir = float2(dir.x * cs - dir.y * sn, dir.x * sn + dir.y * cs);\n \}\n\n float2 sPos = p;\n if (mode == 1) \{\n sPos = p - float2(dirLin.x, dirLin.y / asp) * (d * maxRadius);\n \} else if (mode == 2) \{\n dir.y /= asp;\n sPos = c + dir;\n \} else \{\n float scale = 1.0f + d;\n if (fabs(scale) < 1.0e-4f) scale = (scale < 0.0f) ? -1.0e-4f : 1.0e-4f;\n dir = dir / scale;\n dir.y /= asp;\n sPos = c + dir;\n \}\n\n SampleType(src) s = bilinear(src, sPos.x, sPos.y);\n acc.x += s.x * wRGB\[i].x;\n acc.y += s.y * wRGB\[i].y;\n acc.z += s.z * wRGB\[i].z;\n if (s.w > aMax) aMax = s.w;\n \}\n \}\n\n float4 outp;\n outp.x = acc.x;\n outp.y = acc.y;\n outp.z = acc.z;\n outp.w = (alphaMode == 1) ? aMax : srcCol.w;\n dst() = outp;\n \}\n\};\n"
rebuild ""
SpectralCA_amount {{parent.amount}}
SpectralCA_samples {{parent.samples}}
SpectralCA_focusNm {{parent.focusNm}}
SpectralCA_lambdaMin {{parent.lambdaMin}}
SpectralCA_lambdaMax {{parent.lambdaMax}}
SpectralCA_mode {{parent.mode}}
SpectralCA_curve {{parent.curve}}
SpectralCA_invert {{parent.invert}}
SpectralCA_alphaMode {{parent.alphaMode}}
SpectralCA_center {{parent.center.x} {parent.center.y}}
SpectralCA_formatSize {{width} {height}}
SpectralCA_aspect {{parent.aspect}}
SpectralCA_protect {{parent.protect}}
SpectralCA_falloff {{parent.falloff}}
SpectralCA_angleDeg {{parent.angleDeg}}
SpectralCA_spinDeg {{parent.spinDeg}}
SpectralCA_fringeSat {{parent.fringeSat}}
rebuild_finalise ""
name SpectralCA_kernel
xpos 0
ypos -200
}
Merge2 {
inputs 2+1
operation copy
name MergeOut
xpos 0
ypos -80
}
CopyBBox {
inputs 2
name CopyBBox1
xpos 0
disable {{!parent.preserveBBox}}
}
Output {
name Output1
xpos 0
ypos 80
}
end_group