The Filter Gallery's effects, six missing classics, and five more Neural Filters

[IAmJSD]

Fifty-eight filters: 57 → 115, across fourteen categories. This closes the three gaps from the last message's inventory.

Stacks on #66 — that commit is in this branch, and the README paragraph it fixed is rewritten again here, so merging this makes #66 redundant.

The Filter Gallery — 46 effects

The Gallery was a stacker with nothing of its own to stack: it listed the filters already in the menu. These are what people open it for.

group	effects
Artistic (15)	Colored Pencil, Cutout, Dry Brush, Film Grain, Fresco, Neon Glow, Paint Daubs, Palette Knife, Plastic Wrap, Poster Edges, Rough Pastels, Smudge Stick, Sponge, Underpainting, Watercolor
Brush Strokes (8)	Accented Edges, Angled Strokes, Crosshatch, Dark Strokes, Ink Outlines, Spatter, Sprayed Strokes, Sumi-e
Sketch (14)	Bas Relief, Chalk & Charcoal, Charcoal, Chrome, Conté Crayon, Graphic Pen, Halftone Pattern, Note Paper, Photocopy, Plaster, Reticulation, Stamp, Torn Edges, Water Paper
Texture (6)	Craquelure, Grain (all ten grain types), Mosaic Tiles, Patchwork, Stained Glass, Texturizer
Distort (3)	Diffuse Glow, Glass, Ocean Ripple

They are registered as ordinary filters, so each appears in its own menu group as well — which is what Photoshop does with Show all Filter Gallery groups and names on — and can be stacked in the Gallery as before.

None of these are anyone's source. They are written from what each effect does to an image, and they share four ideas that now live in util.rs: flatten a picture into regions a brush could have painted, smear a plane along a line (that one is the Brush Strokes group), light a plane as though it were a surface (Bas Relief, Chrome, Note Paper, Plaster, Texturizer), and generate the canvas/sandstone/burlap/brick surfaces rather than ship texture files that could go missing.

One deliberate deviation: Photoshop's Sketch group draws in the foreground and background colours, and a filter here never sees the toolbox, so they draw black on white — which is what those swatches are set to by default and what every one of these effects is pictured with.

Six classics

Blur, Blur More, Sharpen More (fixed radius, no dialog, as they have been since 1990), Custom (the 5×5 kernel editor, opening at the identity — so it joins Offset and Camera Raw on the list of filters that legitimately do nothing at their defaults), HSB/HSL (channels as hue/saturation/brightness, both directions) and Lighting Effects (Phong shading, with the image's own luminance as the bump map, which is what makes it look embossed rather than merely brightened).

The filter dialog scrolls now, because Custom declares twenty-seven parameters.

Five Neural Filters — nine of twelve now run a network

Harmonization, Landscape Mixer, Photo Restoration, Photo to Sketch, Face to Caricature.

Three of these need a second picture, which a filter has never been able to be handed. FilterPlugin::wants_backdrop() is the answer: the host composites what is under the layer — hiding the layer and everything above it, compositing, putting the visibility back — and passes it to apply_over. So:

• Harmonization matches a cut-out to its background, which is what Photoshop's asks you to pick a layer for.
• Landscape Mixer transfers a palette band by band through the depth model, because a landscape's colours are stratified by distance and a single global match turns the grass the colour of the sky.
• Color Transfer finally has a reference image instead of a hue slider — the gap Say what Colour Transfer is actually short of #66 admitted to. It still falls back to the hue when there is nothing underneath.

Photo Restoration composes what this build already ships: a median that only fires where a pixel disagrees with its neighbours (a scratch, not an edge), an edge-preserving denoise, the deblocking and detail models, then a tone stretch. Face to Caricature warps from the detector's box plus the proportions a face has when it is looking at the camera — it does not find your features, and the docs say so.

Harmonization, Landscape Mixer and Face to Caricature do nothing without a layer underneath or a face in the picture, and are on the test's expected-no-op list for exactly that reason.

Checked

• The property tests run against all 115: registered, finite and in range, no panic at degenerate sizes, deterministic, and doing something at their defaults unless listed. A new test asserts the three backdrop filters actually move the image towards the backdrop.
• Whole workspace suite green, clippy and rustfmt clean.
• Every new effect eyeballed on a photograph, which is how Cutout stopped posterising each channel separately (it was banding a smooth sky into unrelated hues), Torn Edges stopped speckling and started tearing, and Sumi-e stopped being a threshold.
• Driven headlessly in the app: the Filter menu shows the fourteen groups, Neural Filters lists all twelve, and Custom's twenty-seven sliders scroll.

🤖 Generated with Claude Code