STEALTHMARK · HEAD TO HEAD

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Claude Sonnet 5.5 vs GPT 5.6 Luna

Claude Sonnet 5.5 scores 14.0 points higher overall (62.7 vs 48.7). Claude Sonnet 5.5 scores higher on Newton's Mirror, with its largest category advantage in reflections.

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Overall StealthMark

62.7/100
48.7/100

General Intelligence

45.2/100
24.0/100

Visual Intelligence

76.1/100
67.1/100

Newton's Mirror

Same prompt

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

Claude Sonnet 5.540.8/100

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

The near-field silhouettes, broad perspective and paint contact order are recognizable. Missing outer chains, truncated repetitions and absent ordered imagery within the main and reflected spheres substantially limit the reflection system. Sparse spherical highlights leave much of the curved room and emitter mapping unsupported, despite some plausible planar light sequences.

Prompt withheld

This prompt is held back to prevent benchmaxxing.

GPT 5.6 Luna18.1/100

GPT 5.6 Luna: Newton's Mirror SVG benchmark
Researcher observations

The room enclosure has coherent symmetric perspective, with the overhead panel, sphere and black aligned centrally. The sphere and airborne black occupy substantially lower positions than the reference framing, inconsistent with the prescribed camera aim. The diagonal crimson streak does not establish the required surface transport. Faint wall sphere images provide limited mirrored correspondence, but the shallow floor image, missing receding chains, absent nested sphere imagery and sparse emitter mapping leave most reflection structure unsupported.

Prompt withheld

This prompt is held back to prevent benchmaxxing.

Compare category scores
CategoryClaude Sonnet 5.5GPT 5.6 Luna
State at 600 ms25.0/2515.0/25
Camera and placement15.0/154.0/15
Reflections23.5/1203.5/120
Materials and scale10.0/1010.0/10
Floor-damage reward0.0/100.0/10

Selfie

Different prompts

Claude Sonnet 5.579.0/100

Claude Sonnet 5.5: Selfie SVG benchmark
Researcher observations

The centered coral squid has a friendly, composed expression and a balanced flower-like silhouette. Eight thick arms and two slender tentacles remain visibly connected, with no inverted parts. The mantle is elongated rather than compact, and the arm spacing is uneven. Soft shading gives volume, but dense stippling weakens the requested smooth matte finish; the broad background halo makes depth less precise.

Prompt withheld

This prompt is held back to prevent benchmaxxing.

GPT 5.6 Luna61.8/100

GPT 5.6 Luna: Selfie SVG benchmark
Researcher observations

Six pale, outward-facing heads and six rounded lobes make the knot recognizable. The central hexagonal opening remains clear. However, broad gray crossing panels flatten the weave, several inner joins resemble capped strips, and sparse oversized scale marks leave the bodies looking more like decorated ribbons than living snakes.

Prompt withheld

This prompt is held back to prevent benchmaxxing.

Compare category scores
CategoryClaude Sonnet 5.5GPT 5.6 Luna
Prompt & likeness8.0/107.5/10
Anatomy & construction8.0/106.0/10
Space & placement8.0/106.5/10
Light & reflections7.5/105.0/10
Purposeful detail7.5/105.5/10
Artistry & character8.0/106.5/10
Materials & effects7.0/105.0/10
Visual integrity8.5/106.0/10

Beach

Same prompt

Claude Sonnet 5.582.3/100

Claude Sonnet 5.5: Beach SVG benchmark
Researcher observations

A richly designed beach illustration combines radiant sunset bands, intricate palm fans and playful silhouettes within a cohesive purple, coral and turquoise palette. Carefully varied accessories reward close inspection, while overlapping foreground forms and shoreline layers organize the abundant activity. Dense palm strokes compete with focal subjects; animal anatomy, relative scales and reflected silhouettes remain simplified.

Exact prompt

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

GPT 5.6 Luna67.8/100

GPT 5.6 Luna: Beach SVG benchmark
Researcher observations

The warm sunset, palm silhouette and varied beach activities create an appealing, readable composition. Animals, birds and a broad sun reflection satisfy the brief. Drawing remains elementary: angular airborne sea animals lack splash or convincing motion, the crab's claws are awkwardly constructed, and repeated reflection bands suggest a stepped platform. Clean outlines and pleasant colors exceed the anatomical and spatial sophistication.

Exact prompt

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

Compare category scores
CategoryClaude Sonnet 5.5GPT 5.6 Luna
Prompt & likeness9.0/108.0/10
Anatomy & construction7.0/106.0/10
Space & placement8.5/106.5/10
Light & reflections7.5/106.5/10
Purposeful detail9.0/106.5/10
Artistry & character9.5/107.0/10
Materials & effects7.5/106.0/10
Visual integrity7.5/107.5/10

Mona Lisa

Different prompts

Claude Sonnet 5.563.8/100

Claude Sonnet 5.5: Mona Lisa SVG benchmark
Researcher observations

The crossed hands, dark dress, restrained smile and winding landscape clearly recall the Mona Lisa. Replication is limited by the frontal symmetry, wide eyes, elongated neck and flattened fingers. Soft facial shading provides volume, but heavy darkness and pervasive crackle obscure forms. The composition is coherent; the landscape and fabric remain visibly schematic.

Exact prompt

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

GPT 5.6 Luna63.0/100

GPT 5.6 Luna: Mona Lisa SVG benchmark
Researcher observations

The central portrait, dark clothing, crossed hands and muted landscape clearly evoke Mona Lisa. Replication is limited by the elongated face, conspicuous eyes and simplified smile. Overlapping fingers have uncertain anatomy, while broad gradients and heavy outlines flatten the portrait. The composition and restrained palette remain coherent.

Exact prompt

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

Compare category scores
CategoryClaude Sonnet 5.5GPT 5.6 Luna
Prompt & likeness7.0/106.5/10
Anatomy & construction6.0/106.0/10
Space & placement6.5/106.5/10
Light & reflections6.5/106.5/10
Purposeful detail6.0/105.5/10
Artistry & character6.5/106.5/10
Materials & effects5.5/105.5/10
Visual integrity6.5/107.0/10

Raccoon

Same prompt

Claude Sonnet 5.576.3/100

Claude Sonnet 5.5: Raccoon SVG benchmark
Researcher observations

The raccoon clearly rides on the dog's back while the dog grips the jet ski controls. Expressive faces, vivid colors and a sweeping wake make the scene appealing. Visible limbs connect coherently, but overlapping steering paws and an indistinct control mounting weaken construction. Flat character lighting and simplified water limit depth and material realism.

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

GPT 5.6 Luna70.8/100

GPT 5.6 Luna: Raccoon SVG benchmark
Researcher observations

Expressive animals, a striped tail and clean outlines make the scene appealing and readable. The raccoon sits convincingly on the dog's back, but the overlapping steering paws are ambiguous and the control stem stops above the hull. Broad wake shapes suggest motion; the glowing sun lacks a corresponding water reflection.

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

Compare category scores
CategoryClaude Sonnet 5.5GPT 5.6 Luna
Prompt & likeness8.5/107.5/10
Anatomy & construction7.0/106.5/10
Space & placement7.5/107.0/10
Light & reflections6.5/106.0/10
Purposeful detail8.0/107.5/10
Artistry & character8.0/107.5/10
Materials & effects7.5/106.5/10
Visual integrity8.0/108.0/10

Pelican

Benchmax control

Outside General and Visual Intelligence.

Claude Sonnet 5.576.8/100

Claude Sonnet 5.5: Pelican SVG benchmark
Researcher observations

The pelican is immediately recognizable, with an expressive face, generous bill and appealing cycling pose. Spokes, chain, feathers and scarf provide purposeful detail. The bicycle largely holds together, though overlapping angular legs obscure the far foot’s pedal contact. Clean outlines and balanced composition succeed; flat surfaces and limited directional lighting constrain depth.

Exact prompt

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

GPT 5.6 Luna76.0/100

GPT 5.6 Luna: Pelican SVG benchmark
Researcher observations

A recognizable pelican cyclist with an expressive profile, balanced composition and controlled outlines. Head, neck and torso connect coherently. The bicycle wheels and frame are convincing, but overlapping feet obscure pedal contact, the drivetrain lacks a clear chain, and the wing's handlebar grip is schematic. Atmospheric color succeeds more strongly than directional lighting or material depth.

Exact prompt

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

Compare category scores
CategoryClaude Sonnet 5.5GPT 5.6 Luna
Prompt & likeness9.0/108.5/10
Anatomy & construction7.5/107.0/10
Space & placement7.5/107.5/10
Light & reflections6.5/106.5/10
Purposeful detail8.0/107.5/10
Artistry & character7.5/108.0/10
Materials & effects6.5/107.0/10
Visual integrity8.0/108.5/10