[Experiment] Comparing 6 Lighting Types — How Do Effects Change Between Beach and Indoor Bar?

Conclusions First

• neon lighting produces stable effects in 3 out of 3 in both beach and bar scenes. Magenta/cyan color cast and neon sign appearance are characteristic
• golden hour is scene-dependent. Only 1 out of 3 in the beach scene, but 3 out of 3 in the bar produced warm color temperature. The darker the environment, the more likely effects appear
• hard direct sunlight is also scene-dependent. No effect on the beach (already a direct sunlight environment), but brightness increase was confirmed in 3 out of 3 in the bar. However, hard shadows did not appear
• backlit and rim lighting have low reproducibility in both beach and bar. Controlling light direction with lighting keywords alone is difficult
• The effectiveness of lighting specifications is determined by the difference from the scene’s default lighting — darker environments tend to show effects more easily

Experiment Design

Only the lighting specification is changed as a single variable, observing its effect on a beach bikini portrait.

Model & Parameters

Base Prompt

The {LIGHTING} section is swapped per condition. For control, {LIGHTING} is removed, leaving no lighting specification.

Condition List

Evaluation Criteria

• Light direction and intensity
• Changes in skin highlights and shadows
• Changes in overall color tone and atmosphere
• Effects on background

Results for Each Condition

A00: Control (No Lighting Specification)

Seed 42	Seed 123	Seed 789

Observation

All 3 show midday natural light with flat, slightly overhead frontal lighting. Skin highlights are evenly distributed on the chest, shoulders, and forehead, with short shadows falling at the subject’s feet. Sky is clear blue. Sand is bright beige. Overall color temperature is neutral to slightly cool. Bikini color (light blue, blue, pink) and background composition (palm trees, etc.) differ by seed, but lighting quality is consistent across all 3.

A01: Backlit

Seed 42	Seed 123	Seed 789

Observation

Almost no visible difference from control was confirmed in all 3. Light direction remains frontal to slightly overhead; backlit effects (highlights along hair and shoulder contours, stronger facial shadows from behind) were confirmed in 0 out of 3. Skin highlight distribution, shadow direction, and background brightness are all equivalent to control. Seed 123 shows a striped bikini and rocky scene background — composition changed — but the quality of light is indistinguishable from control.

A02: Rim Lighting

Seed 42	Seed 123	Seed 789

Observation

No clear difference from control was confirmed. The narrow rim highlight line along the subject’s contour — a characteristic of rim lighting — was observed in 0 out of 3. Light direction remains frontal to slightly overhead, same as control. Seed 789 shows a white bikini with slightly stronger highlights around the shoulders, but comparison with control’s seed 789 shows minimal difference — not determinable as a rim lighting-specific effect.

A03: Golden Hour

Seed 42	Seed 123	Seed 789

Observation

Warm color temperature typical of evening was confirmed in 1 out of 3 (seed 123). Seed 123 shows the sky shifting toward orange/gold tones, with warm color cast on the sand and skin. However, seeds 42 and 789 remain at the same neutral color temperature as control, with blue sky unchanged. The long shadows typical of golden hour’s low sun angle were not confirmed in any of the 3. Effect appeared in only 1 out of 3 — low reproducibility.

A04: Neon Lighting

Seed 42	Seed 123	Seed 789

Observation

The most visually significant change of all 6 conditions. The following common changes were confirmed in 3 out of 3:

• Background change: Sky shifts to overcast/dusk dark tone, clearly different from control’s bright blue sky
• Skin color cast: Seed 42 shows asymmetric magenta/cyan light hitting the skin from both sides. Seed 123 has the bikini changed to fluorescent stripes, with strong purple/pink reflected light visible on skin
• Overall brightness decrease: All 3 are darker toned, greatly departing from control’s bright outdoor daytime brightness
• Bikini color change: Seed 789 shows a fluorescent pink bikini — neon-colored clothing may have been induced

Despite being an outdoor beach environment, neon lighting was confirmed to forcibly shift the lighting conditions to night/dusk.

A05: Hard Light

Seed 42	Seed 123	Seed 789

Observation

No clear difference from control was confirmed. The characteristics of hard light — sharply defined dense shadows, strong contrast, near-blown highlights — were observed in 0 out of 3. Shadow density, direction, and length are all equivalent to control, and skin highlights remain soft. Since the beach scene already implicitly applies outdoor direct sunlight through the base prompt alone, adding hard direct sunlight may have produced no change.

Deep Dive: Re-testing Lighting in an Indoor Bar

In the first phase (beach), 4 out of 5 conditions were absorbed by the default natural light and no effects were confirmed. To determine whether this was specific to the bright outdoor beach scene, the same 6 conditions were retested in a dark indoor bar.

Base Prompt

The {LIGHTING} section is swapped per condition. For control, {LIGHTING} is removed. Seeds 42, 123, 789 are the same as Phase 1.

Condition List

D00: Control (No Lighting Specification)

Seed 42	Seed 123	Seed 789

Observation

All 3 show the subject standing in front of a bar counter, with shelves lined with bottles in the background. Lighting is primarily warm-tone pendant lights from the ceiling, with overall dark ambient. Skin highlights are concentrated on the face and front of the arms, with soft shadows. The backlit shelves illuminate the bottles. Compared to the beach control, overall brightness is significantly lower — the dark indoor bar environment is reproduced.

D01: Backlit

Seed 42	Seed 123	Seed 789

Observation

Seed 789 shows the shelf lighting in the background glowing strongly like a surface light source, with the subject’s silhouette falling darker — a backlit-style rendering was confirmed. The subject’s front is dark, with a large brightness contrast against the background. Seeds 42 and 123 show minimal difference from control, though seed 42 shows slightly suppressed frontal lighting on the subject. While 0 out of 3 showed backlit effects in the beach, the bar showed a clear effect in 1 out of 3.

D02: Rim Lighting

Seed 42	Seed 123	Seed 789

Observation

Seed 789 shows the shelf lighting changed to linear indirect lighting, with light streaks along the shelf edges visible. Direct rim lighting effects on the subject (highlights along hair and shoulder contours) are not clear in any of the 3, but the background lighting arrangement is more indirect than in control. Seeds 42 and 123 show minimal difference from control — rim lighting effects on the subject remain poorly reproducible, as in the beach scene.

D03: Golden Hour

Seed 42	Seed 123	Seed 789

Observation

Warm color temperature changes were confirmed in 3 out of 3. Seed 42 shows the bar counter wall shifting to gold/amber tones, with the ceiling pendant lights emitting more orange light. Seed 123 also has wall and shelf tones unified in gold tones. Seed 789 shows warm evening light streaming in through a lattice window, with orange highlights visible on the subject’s hair and shoulders. The effect that appeared in 1 out of 3 in the beach now appeared in 3 out of 3 in the bar — a significant improvement in reproducibility.

D04: Neon Lighting

Seed 42	Seed 123	Seed 789

Observation

Clear neon lighting effects were confirmed in 3 out of 3. Seed 42 shows magenta/cyan neon light visible in the bar background, with color light reflection on the subject. Seed 123 shows a cyan neon sign appearing in the background, with a faint color reflection on the subject’s skin. Seed 789 shows pink/cyan neon signs reflected in windows, with neon color cast across the entire interior. While 3 out of 3 were effective in the beach too, in the bar scene neon signs naturally integrate as props, showing better scene coherence than the beach.

D05: Hard Light

Seed 42	Seed 123	Seed 789

Observation

All 3 out of 3 show overall brightness increased compared to control, with the scene changing to depict daytime light streaming into the interior. Seed 42 has the dress silhouette changed to a pleated skirt, with an overall cafe-like bright atmosphere. Seed 123 shows brighter interior lighting — a daytime operation impression rather than the dark bar of control. Seed 789 also shows strong light from above with more highlights on skin and hair. In the beach scene, hard direct sunlight added no change because outdoor direct sunlight was already the default; in the bar, bringing direct sunlight into a dark interior produced a clear brightness change. However, “hard shadow” characteristics (sharp shadow boundaries, strong contrast) were confirmed in 0 out of 3.

Cross-Comparison (Same Seed)

Condition	Seed 42	Seed 123	Seed 789
Control
Backlit
Rim Lighting
Golden Hour
Neon Lighting
Hard Light

Deep Dive Summary

The bar re-test confirmed changes in many of the conditions that showed no effect in the beach.

Of the 4 conditions that were “absorbed by beach natural light” in Phase 1, golden hour and hard direct sunlight clearly appeared in the bar scene. golden hour brings out warm color temperature changes in dark environments, and hard direct sunlight was confirmed through brightness changes contrasting with interior darkness. Meanwhile, backlit and rim lighting remained poorly reproducible even in the bar — confirming that controlling light direction is difficult regardless of scene change.

The effectiveness of lighting specifications is determined by the difference from the scene’s default lighting. In already-bright outdoor environments, many conditions are absorbed; but in dark interiors, lighting additions and color temperature changes are more visually apparent.

Note: golden hour reached 3/3 in the bar but only 1/3 on the beach, suggesting the color temperature shift stands out more in a darker environment. hard direct sunlight also showed a brightness-increasing change indoors. Meanwhile, backlit and rim lighting remained poorly reproducible even in the bar, indicating that controlling light direction is still difficult.

Summary

Comparing 6 lighting specifications across two scenes — beach (outdoor daytime) and bar (dark indoor).

The effectiveness of lighting specifications is determined by the difference from the scene’s default lighting. In already-bright outdoor environments, most conditions are absorbed by default natural light; but in dark interiors, lighting additions and color temperature changes are more visually apparent.

In practical use, the following distinctions are considered effective:

• When changing color temperature: golden hour (use in dark environments) or neon lighting (effective regardless of environment)
• When changing overall scene atmosphere: neon lighting is most stable
• When controlling light direction: Both backlit and rim lighting have low reproducibility — currently limited practical value

Cross-Comparison: Beach (Same Seed)

Condition	Seed 42	Seed 123	Seed 789
Control
Backlit
Rim Lighting
Golden Hour
Neon Lighting
Hard Light

Note: The key takeaway from this experiment is that the effectiveness of lighting specifications is determined by the difference from the scene’s default lighting. On the beach, natural light is strong and absorbs most conditions, while in a dark environment like a bar, golden hour and hard direct sunlight produced visible changes. neon lighting was stable at 3/3 in both scenes. backlit and rim lighting remained ineffective regardless of scene, suggesting that controlling light direction requires more specific wording.

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