Intaglio
Your clip as a copper engraving, for Resolume
What it does
An FFGL effect for Resolume Arena and Avenue. An engraving has no greys. The plate has lines, and tone comes from how close together they are and how fat each one is: a line swells where the tone darkens and tapers where it lightens. Intaglio is built entirely on that. Each point's darkness becomes a coverage, and the line's width is that coverage times the pitch, so a mid-grey prints lines exactly as wide as the paper between them. At the dark end the line is as wide as the pitch and the plate goes solid, and at the light end it tapers away to nothing.
The shading of an engraving, detail that survives in the darks as line weight instead of mud, and the moiré where two hatch sets cross all come from that model. None of them is drawn separately. When one set of lines runs out of range, a second and then a third come in at other angles, gradually and below a threshold, so the cross-hatching arrives with the shadows. However many sets are in, their union is worked out so the plate still prints the tone it was asked for.
The lines follow the picture because they follow a flow field built from the structure tensor of the tone. It's the same field nib draws its strokes along, copied across rather than worked out a second time. Where the two plugins differ is a flat grey area: nib draws nothing there, because there's no edge, and Intaglio fills it with evenly spaced lines at the pitch and weight that grey needs. Turn Coherence to zero and the flow is ignored, leaving a plain hatch at one angle across the whole frame. That's the effect with the idea taken out, one slider away.
The plate behaves like a real one: ink and paper colours, the veil of ink a wiped plate keeps, an uneven bite, and the burr a drypoint needle throws up beside its furrow, which holds extra ink on one side of every line. Invert makes a white-line engraving, where the burin cuts the highlights instead of the shadows, which gives you a different drawing from just swapping the two colours.
Every length is a fraction of the frame height, never a number of pixels, so the same settings give the same drawing at 720p and at 4K. The tests check that too: every measurement runs at two rasters and fails if they disagree.
- Tone carried by line weight: solid at black, bare paper at white, measured at both ends
- A ruling that follows the picture, on the structure-tensor flow field copied from nib
- Coherence at zero falls back to a plain global hatch, so the comparison is one slider
- One to three hatch sets, each engaging with the shadows, with the union kept exact
- Line Pitch in lines across the frame, a weight curve, and floor and ceiling weights
- Detect on luminance, a single channel or saturation, whichever carries the picture
- Ink and paper colours, plate tone, bite and drypoint burr
- Invert for a white-line engraving, not a colour swap
- Universal macOS bundle and a Windows x64 DLL
Where it stands
v0.1.0, and early days. It hasn't been loaded into Resolume on macOS yet. On Windows it has: a build loads, registers and renders in Resolume Arena 7.27.1 on software rendering (no GPU), passing all nine of the fleet's host checks with every parameter as declared and every control moving the picture. The central claims are measured by an offline harness driving the real plugin, with every check run at two rasters and failing if they disagree: black prints full coverage and white none, for one, two and three sets; coverage follows the weight curve to within 0.0005 at five tones; the line count across a window comes out right; lines come out perpendicular to a known gradient and a 62° cross-hatch measures 62.00°; and the flow field sits 0.49° from the test rings' true tangent at its best setting. It catches five models that are wrong on purpose, and all 25 controls change the picture. It costs 0.59 ms a frame at 720p, 1.19 at 1080p and 4.57 at 4K on Apple Silicon. Where the flow turns sharply the ruling is an approximation, and lines converge, shear and split, because an evenly spaced family of curves following an arbitrary field doesn't exist. Three hatch sets at exactly 60° over-cover by about 2.5%, and the finest rulings on a 4K frame alias. There's a user guide and a browser demo, which is a port rather than the plugin, but no OpenFX port and no factory presets. Try it in your own rig before you trust it in a show.
Watch it running
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