STEALTHMARK · HEAD TO HEAD

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Claude Opus 5.5 vs Union Alpha

Claude Opus 5.5 scores 6.0 points higher overall (66.0 vs 60.0). Claude Opus 5.5 scores higher on Newton's Mirror, with its largest category advantage in reflections. Union Alpha’s overall score includes one estimated scene.

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Overall StealthMark

66.0/100
60.0/100Estimated · 1 missing scene

General Intelligence

55.3/100
40.9/100Partial coverage

Visual Intelligence

74.5/100
73.2/100Partial coverage

Newton's Mirror

Same prompt

Physics, perspective and recursive reflections, tested together. Explore the test ↗

Claude Opus 5.552.5/100

Claude Opus 5.5: Newton's Mirror SVG benchmark
Researcher observations

Open lateral sightlines, first reflected silhouettes and near-field planar panel placement are convincing. Missing outer chains, truncated repetitions and absent nested spherical room and emitter imagery remain the main weaknesses.

Prompt withheld

This prompt is held back to prevent benchmaxxing.

Union Alpha38.3/100

Union Alpha: Newton's Mirror SVG benchmark
Researcher observations

Recognizable near-field sphere placement and bilateral convergence provide limited optical structure. Broad gray regions interrupt lateral sightlines and truncate side-floor images. Missing outer chains, absent nested sphere imagery and incomplete planar and curved emitter mappings dominate the reflection system.

Prompt withheld

This prompt is held back to prevent benchmaxxing.

Compare category scores
CategoryClaude Opus 5.5Union Alpha
State at 600 ms25.0/2525.0/25
Camera and placement15.0/1515.0/15
Reflections46.5/12019.0/120
Materials and scale8.0/1010.0/10
Floor-damage reward0.0/100.0/10

Selfie

Claude Opus 5.578.3/100

Claude Opus 5.5: Selfie SVG benchmark
Researcher observations

The centered coral squid has a friendly, restrained expression and a balanced radial silhouette within a cream arch. Smooth curves and soft shading give it an appealing matte finish. The mantle is more elongated than compact, the upper arms are visually ambiguous, and the two hanging tentacles read somewhat like legs. Clean execution supports a strong stylized illustration.

Prompt withheld

This prompt is held back to prevent benchmaxxing.

Compare category scores
CategoryClaude Opus 5.5Union Alpha
Prompt & likeness8.0/10—
Anatomy & construction7.5/10—
Space & placement8.0/10—
Light & reflections7.5/10—
Purposeful detail7.5/10—
Artistry & character8.0/10—
Materials & effects7.5/10—
Visual integrity8.5/10—

Beach

Different prompts

Claude Opus 5.578.0/100

Claude Opus 5.5: Beach SVG benchmark
Researcher observations

A lively, well-composed beach illustration with rich sunset colors, recognizable animals and appealing accessories. The sun reflection establishes a strong central focus. Clean silhouettes and small details reward inspection, though simplified animal construction, uneven contact shadows and mostly flat materials limit depth and realism.

Exact prompt

Create an SVG of a amazing beach scene. Sunset, animals, fun, birds, reflections Make it a masterpiece, no tools allowed

Union Alpha80.0/100

A beach at sunset with a palm tree, turtle, crab, birds, and a leaping dolphin.
Researcher observations

A cohesive sunset palette, sweeping shoreline and playful animals make an appealing beach illustration. The sun’s reflection establishes a clear focal axis, balanced by the palm and umbrella. Clean silhouettes and small decorative features reward inspection, though simplified anatomy, repetitive reflection bars and generic oval shadows limit volume and naturalism.

Exact prompt

Create an SVG of a amazing beach scene. Sunset, animals, fun, birds, reflections

Compare category scores
CategoryClaude Opus 5.5Union Alpha
Prompt & likeness8.5/109.0/10
Anatomy & construction7.5/107.5/10
Space & placement7.0/108.0/10
Light & reflections8.0/107.5/10
Purposeful detail8.0/108.0/10
Artistry & character8.0/108.0/10
Materials & effects6.5/107.0/10
Visual integrity8.5/108.5/10

Mona Lisa

Different prompts

Claude Opus 5.564.8/100

Claude Opus 5.5: Mona Lisa SVG benchmark
Researcher observations

The portrait preserves the recognizable composition, dark veil, folded hands and distant landscape. Replication is limited by the elongated face and neck, conspicuous eyes and simplified smile. Hands remain connected but their rounded fingers and wrists lack convincing anatomy. Restrained colors create cohesion; shallow modeling and pervasive mottling weaken volume and painterly subtlety.

Exact prompt

Replicate mona-lisa as SVG Make it a masterpiece, no tools allowed

Union Alpha64.0/100

An SVG interpretation of the Mona Lisa, with folded hands and a landscape background.
Researcher observations

The centered portrait, folded hands, dark clothing and hazy landscape clearly evoke the Mona Lisa. Muted colors and soft facial shading create a coherent illustration, but replication remains schematic: the face is broad, eyes outlined, smile simplified and overlapping fingers poorly resolved. Angular landscape shapes and flat fabric limit depth and painterly richness.

Exact prompt

Replicate mona-lisa as SVG

Compare category scores
CategoryClaude Opus 5.5Union Alpha
Prompt & likeness7.0/107.0/10
Anatomy & construction6.0/106.0/10
Space & placement6.5/106.5/10
Light & reflections6.0/106.5/10
Purposeful detail6.5/105.5/10
Artistry & character6.5/106.5/10
Materials & effects6.5/105.0/10
Visual integrity7.0/107.5/10

Raccoon

Different prompts

Claude Opus 5.575.0/100

Claude Opus 5.5: Raccoon SVG benchmark
Researcher observations

The masked raccoon clearly rides the dog's back, and the dog's forward paw reaches the steering grip. Expressive faces, vivid colors and sweeping wakes create an appealing illustration. Connected limbs remain schematic, as does the small steering assembly. The broad hull and flat foam weaken water contact; the glowing sun lacks a corresponding reflection or convincing cast shadows.

Exact prompt

Generate an SVG: A raccoon sits on a dog's back while the dog steers a jet ski Make it a masterpiece, no tools allowed

Union Alpha72.0/100

A raccoon rides on a dog as the dog steers a red jet ski.
Researcher observations

Expressive animals, a readable riding arrangement and sweeping spray create an appealing cartoon. The raccoon sits convincingly on the dog's back, but the dog's paw does not clearly grip the handlebar, whose connection to the hull is unresolved. Flat lighting provides little volume or reflection. A dark rectangular strip interrupts the upper-right background.

Exact prompt

A raccoon sits on a dog's back while the dog steers a jet ski

Compare category scores
CategoryClaude Opus 5.5Union Alpha
Prompt & likeness8.5/108.0/10
Anatomy & construction7.0/106.5/10
Space & placement7.5/107.5/10
Light & reflections6.0/105.5/10
Purposeful detail7.5/107.5/10
Artistry & character8.0/108.0/10
Materials & effects7.0/107.5/10
Visual integrity8.0/107.0/10

Pelican

Benchmax control

Outside General and Visual Intelligence.

Claude Opus 5.572.5/100

Claude Opus 5.5: Pelican SVG benchmark
Researcher observations

The recognizable pelican, orderly bicycle wheels and harmonious sunset create an appealing illustration. Both legs connect to the body and reach pedals; no clear detached or inverted parts appear. Steering contact and seating support are less convincing, while the drivetrain remains schematic. Crisp outlines give a clean finish, but limited shading and flat surfaces leave the scene with modest depth.

Exact prompt

Generate an SVG of a pelican riding a bicycle Make it a masterpiece, no tools allowed

Union Alpha73.8/100

A pelican riding a teal bicycle beneath a sunny blue sky.
Researcher observations

The pelican is immediately recognizable, with an expressive face, convincing bill silhouette and appealing pastel composition. Both legs connect to feet, and the wing reaches the handlebar. Bicycle construction is less resolved: the far pedal lacks a clear crank connection and no chain is visible. Clean contours and orderly spokes support the illustration, while flat lighting and simplified surfaces limit depth.

Exact prompt

Generate an SVG of a pelican riding a bicycle

Compare category scores
CategoryClaude Opus 5.5Union Alpha
Prompt & likeness8.5/108.5/10
Anatomy & construction6.5/106.5/10
Space & placement7.0/107.5/10
Light & reflections6.0/106.0/10
Purposeful detail7.5/107.0/10
Artistry & character7.5/108.0/10
Materials & effects6.0/106.5/10
Visual integrity8.5/108.5/10