Conclusions First
- Length-based prompts (short hair / long hair / medium hair) are reliably controllable. All 3 seeds reproduce the specified length consistently with minimal side effects. The most dependable foundation for hair control.
- Arrangement prompts like ponytail / bun / braid are also high-precision. Ponytail, bun, and braid appear clearly in 3 out of 3 images. However,
bun may trigger a Japanese clothing change. - Cut-based prompts like bob cut / pixie cut are also stable. Bob cut in particular reproduces a chin-line bob consistently across all 3 seeds. Pixie cut also reliably produces short hair with exposed ears.
- Wolf cut has a serious side effect where wolf illustrations appear. The model doesn’t recognize it as a hairstyle and literally draws wolves in the background. Not recommended.
- State-based prompts (disheveled / bedhead) are strong for wet/messy hair expression. However, they tend to change the outfit toward tank tops and camisoles.
Recommended Prompt Rankings
| Rank | Prompt | Accuracy | Stability | Side Effects | Rating |
|---|
| 1 | ponytail | ○ | 3/3 | None | ★★★ |
| 2 | short hair | ○ | 3/3 | None | ★★★ |
| 3 | long hair | ○ | 3/3 | None | ★★★ |
| 4 | bob cut | ○ | 3/3 | None | ★★★ |
| 5 | twin braids | ○ | 3/3 | None | ★★★ |
| 6 | pixie cut | ○ | 3/3 | None | ★★★ |
| 7 | curly hair | ○ | 3/3 | None | ★★★ |
| 8 | high ponytail | ○ | 3/3 | None | ★★★ |
| 9 | braid | ○ | 3/3 (count unstable) | None | ★★ |
| 10 | twintails | ○ | 3/3 | Minor | ★★ |
Experiment Design
| Item | Value |
|---|
| Model | z-image-turbo (6B, photorealistic distillation) |
| Steps | 8 |
| CFG | 1.0 |
| Resolution | 1024×1024 |
| Conditions | 31 (including control) |
| Seeds | 3 (fixed for all conditions) |
| Total images | 93 |
| Changed variable | Hair style prompt only (1 variable) |
Base Prompt
1girl, 32yo japanese actress, {HAIR_STYLE}, standing, facing camera, upper body, simple white background, soft studio lighting
The {HAIR_STYLE} part is replaced with each condition’s prompt. The control (A00) has no hair style specified.
Evaluation Criteria
- Accuracy — How closely the output matches the specified style (○: clear match / △: partial match / ×: no match)
- Stability — Number of matching seeds out of 3 (3/3, 2/3, 1/3, 0/3)
- Side effects — Unintended changes to non-hair elements (outfit, background, composition, etc.)
- Rating — Overall evaluation (★★★ / ★★ / ★ / −)
A. Length-Based (5 conditions)
A00: Control (no hair style specified)
1girl, 32yo japanese actress, standing, facing camera, upper body, simple white background, soft studio lighting
Observation: All 3 images show medium-length hair around the shoulder/collarbone area with a light wave. Bangs are around eye level. The default hair in control is natural medium-length hair.
A01: long hair
1girl, 32yo japanese actress, long hair, standing, facing camera, upper body, simple white background, soft studio lighting
Observation: 3 out of 3 images reproduce long hair reaching below the chest or to the waist. Clearly longer than the control. Seed 3 shows an umbrella-like object in the background, but the hair itself is stable. Minor side effects.
A02: short hair
1girl, 32yo japanese actress, short hair, standing, facing camera, upper body, simple white background, soft studio lighting
Observation: 3 out of 3 images show short hair with ears visible, at or above jaw-line. Clearly shorter than the control’s medium hair. Outfit changes (seed 3 has a patterned top) but the hair is unaffected.
A03: medium hair
1girl, 32yo japanese actress, medium hair, standing, facing camera, upper body, simple white background, soft studio lighting
Observation: 3 out of 3 show medium-length hair around shoulder/collarbone, essentially the same as control. Since the default is already medium, explicit specification doesn’t add much difference. Seed 3 has a decorative umbrella object covering much of the frame as a side effect.
A04: short bob cut
1girl, 32yo japanese actress, short bob cut, standing, facing camera, upper body, simple white background, soft studio lighting
Observation: 3 out of 3 show a neatly trimmed bob shorter than the jaw-line. The ends curl inward and it’s clearly identifiable as a short bob. A significant change from control in hair length and silhouette. High control precision.
Group A Summary
| Condition | Prompt | Accuracy | Stability (out of 3) | Side Effects | Rating |
|---|
| A00 | (none) | — | — | — | — |
| A01 | long hair | ○ | 3/3 | None | ★★★ |
| A02 | short hair | ○ | 3/3 | None | ★★★ |
| A03 | medium hair | ○ | 3/3 | None | ★★ |
| A04 | short bob cut | ○ | 3/3 | None | ★★★ |
B. Arrangement-Based (10 conditions)
B01: ponytail
1girl, 32yo japanese actress, ponytail, standing, facing camera, upper body, simple white background, soft studio lighting
Observation: 3 out of 3 clearly reproduce a single tied ponytail at the back of the head. Hair gathered back while leaving front bangs, visible from side and rear angles. No side effects on outfit or background.
B02: high ponytail
1girl, 32yo japanese actress, high ponytail, standing, facing camera, upper body, simple white background, soft studio lighting
Observation: 3 out of 3 reproduce a ponytail tied near the top of the head. The tie position is clearly higher than B01’s ponytail. Seed 3 changes outfit to a ribbon-trimmed dress, but the hair itself is stably high-positioned.
B03: side ponytail
1girl, 32yo japanese actress, side ponytail, standing, facing camera, upper body, simple white background, soft studio lighting
Observation: 3 out of 3 reproduce a side ponytail with hair gathered to one side. The shape of hair swept to either shoulder is clearly confirmed. Seed 3 has an umbrella object, but hair reproduction is accurate.
B04: bun
1girl, 32yo japanese actress, bun, standing, facing camera, upper body, simple white background, soft studio lighting
Observation: 3 out of 3 reproduce a hair bun at the crown or back of the head. However, seed 1 and 3 show outfit changes to Japanese clothing (kimono/yukata). bun tends to be associated with traditional Japanese attire. Hair style reproduction itself is accurate.
B05: messy bun
1girl, 32yo japanese actress, messy bun, standing, facing camera, upper body, simple white background, soft studio lighting
Observation: 3 out of 3 reproduce a loose, relaxed bun. Compared to B04’s bun, more loose strands and a less tidy gathering. Seed 3 changes to a knitwear top. The looseness of the hairstyle is consistent across seeds.
B06: updo
1girl, 32yo japanese actress, updo, standing, facing camera, upper body, simple white background, soft studio lighting
Observation: 3 out of 3 reproduce an updo with hair gathered up. Seeds 1-2 show chignon-style, seed 3 shows hair gathered at a slightly higher position. Compared to bun, the styling is more formal with fewer loose strands. Minor side effects.
B07: braid
1girl, 32yo japanese actress, braid, standing, facing camera, upper body, simple white background, soft studio lighting
Observation: 3 out of 3 reproduce a braid, but seed 1 has a single braid while seeds 2 and 3 have two braids. The number of braids is unstable with braid alone. The braiding structure itself is clearly visible with high accuracy.
B08: french braid
1girl, 32yo japanese actress, french braid, standing, facing camera, upper body, simple white background, soft studio lighting
Observation: 2 out of 3 show a French braid starting from near the crown. The difference from B07’s braid is that the braid starts near the top of the head. Seed 3 has a large fabric/umbrella object covering much of the frame. Slightly lower precision than basic braid.
B09: twin braids
1girl, 32yo japanese actress, twin braids, hair divided into two braids resting on shoulders, standing, facing camera, upper body, simple white background, soft studio lighting
Observation: 3 out of 3 reproduce two braids split left and right hanging on the shoulders. The braiding pattern is clearly visible and consistently recognized. Seed 3 has the background shift slightly gray and outfit change to casual sweatshirt. Hair accuracy is high.
B10: twintails
1girl, 32yo japanese actress, twintails, standing, facing camera, upper body, simple white background, soft studio lighting
Observation: 3 out of 3 reproduce two-section twintails split left and right. Unlike twin braids, the hair is not woven and hangs straight. Seed 3 tends to look younger and the outfit changes to a frilly blouse — likely influenced by the “youthful” image associated with twintails.
Group B Summary
| Condition | Prompt | Accuracy | Stability (out of 3) | Side Effects | Rating |
|---|
| B01 | ponytail | ○ | 3/3 | None | ★★★ |
| B02 | high ponytail | ○ | 3/3 | None | ★★★ |
| B03 | side ponytail | ○ | 3/3 | Minor (object appearance) | ★★ |
| B04 | bun | ○ | 3/3 | Moderate (Japanese clothing) | ★★ |
| B05 | messy bun | ○ | 3/3 | Minor | ★★ |
| B06 | updo | ○ | 3/3 | None | ★★★ |
| B07 | braid | ○ | 3/3 (count unstable) | None | ★★ |
| B08 | french braid | △ | 2/3 | Moderate (object appearance) | ★ |
| B09 | twin braids | ○ | 3/3 | None | ★★★ |
| B10 | twintails | ○ | 3/3 | Minor (younger appearance, outfit change) | ★★ |
C. Cut & Texture-Based (8 conditions)
C01: bob cut
1girl, 32yo japanese actress, bob cut, standing, facing camera, upper body, simple white background, soft studio lighting
Observation: 3 out of 3 show a neatly trimmed bob at the jaw-to-shoulder line. Slightly longer than A04’s short bob cut, with evenly trimmed ends typical of a classic bob. Consistently has front bangs. No side effects.
C02: pixie cut
1girl, 32yo japanese actress, pixie cut, standing, facing camera, upper body, simple white background, soft studio lighting
Observation: 3 out of 3 reproduce a pixie cut short enough to fully expose the ears. Even shorter than A02’s short hair, with a short neckline too. Typical pixie style with slightly longer top. Seed 3 has a veil or mesh accessory, but the hair itself is stable.
C03: hime cut
1girl, 32yo japanese actress, hime cut, standing, facing camera, upper body, simple white background, soft studio lighting
Observation: Seeds 1 and 2 look close to a bob cut and don’t reproduce the hime cut features (blunt bangs + straight side sections + long back hair). Seed 3 shows blunt bangs and long straight hair, achieving something close to a hime cut in 1 out of 3. Stability is low.
C04: wolf cut
1girl, 32yo japanese actress, wolf cut, standing, facing camera, upper body, simple white background, soft studio lighting
Observation: 1 out of 3 shows something resembling a layered wolf-cut style, but seed 3 has a severe side effect with large wolf illustrations appearing in the background — the model interpreted “wolf” as an animal rather than a hairstyle. Seeds 1-2 show some layers but don’t look like a typical wolf cut. Not recommended.
C05: layered hair
1girl, 32yo japanese actress, layered hair, standing, facing camera, upper body, simple white background, soft studio lighting
Observation: 3 out of 3 show medium-length hair around the shoulder with some layering. Compared to control there’s slightly more movement at the ends, but the difference is small. Seed 3 has a butterfly illustration side effect. Visual difference from control is hard to distinguish.
C06: undercut
1girl, 32yo japanese actress, undercut, standing, facing camera, upper body, simple white background, soft studio lighting
Observation: 0 out of 3 reproduce an undercut (shaved sides/nape). Seed 1 is a short bob, seed 2 is a chin-length bob, seed 3 is also a bob cut. The shaved section is not confirmed anywhere — processed simply as short hair.
C07: straight hair
1girl, 32yo japanese actress, straight hair, standing, facing camera, upper body, simple white background, soft studio lighting
Observation: 3 out of 3 reproduce straight, sleek hair. Compared to the control’s wavy state, the hair is linear to the ends and neatly smooth. Seed 3 has an umbrella object in the background. Hair control itself is stable.
C08: outward flip medium hair
1girl, 32yo japanese actress, outward flip medium hair, ends flipped outward at shoulder length, standing, facing camera, upper body, simple white background, soft studio lighting
Observation: 2 out of 3 show medium-length hair at shoulder level with ends flipping outward. However, the flip is subtle and not always a definitive outward flip. Seed 3 shows a wall full of posters and flyers as a background side effect.
Group C Summary
| Condition | Prompt | Accuracy | Stability (out of 3) | Side Effects | Rating |
|---|
| C01 | bob cut | ○ | 3/3 | None | ★★★ |
| C02 | pixie cut | ○ | 3/3 | Minor (accessory appearance) | ★★★ |
| C03 | hime cut | △ | 1/3 | Minor | ★ |
| C04 | wolf cut | × | 1/3 | Major (wolf illustration) | − |
| C05 | layered hair | △ | 3/3 | Minor (butterfly illustration) | ★ |
| C06 | undercut | × | 0/3 | None | − |
| C07 | straight hair | ○ | 3/3 | Minor (object appearance) | ★★ |
| C08 | outward flip medium hair | △ | 2/3 | Moderate (background change) | ★ |
D. Texture & Placement-Based (5 conditions)
D01: wavy hair
1girl, 32yo japanese actress, wavy hair, standing, facing camera, upper body, simple white background, soft studio lighting
Observation: 3 out of 3 reproduce hair with large, pronounced waves. The undulation is clearly larger and more voluminous than the control’s light wave. Minor side effects. Stable for hair control.
D02: curly hair
1girl, 32yo japanese actress, curly hair, standing, facing camera, upper body, simple white background, soft studio lighting
Observation: 3 out of 3 reproduce tight curly hair. The curl is tighter than D01’s wavy hair with significantly more volume. Seed 3 shows an outfit change (turtleneck etc.), but the curly hair itself is stable across all seeds.
D03: afro
1girl, 32yo japanese actress, afro, standing, facing camera, upper body, simple white background, soft studio lighting
Observation: 3 out of 3 reproduce a dense natural afro covering the entire head. Even larger volume than D02’s curly hair with an almost spherical silhouette. Seed 3 is particularly voluminous. Some seeds show slight skin tone changes, possibly afro influencing ethnicity perception.
D04: dreadlocks
1girl, 32yo japanese actress, dreadlocks, standing, facing camera, upper body, simple white background, soft studio lighting
Observation: 3 out of 3 reproduce rope-like dreadlocks. A gradient color (brown to gold) is visible from root to tip. Outfit tends to change to knitwear/sweater. Hair style accuracy itself is high.
D05: side-gathered hair
1girl, 32yo japanese actress, side-gathered hair, all hair swept to one side of the neck, standing, facing camera, upper body, simple white background, soft studio lighting
Observation: 2 out of 3 show hair gathered to one side. Seed 1 is close to a low ponytail, seed 2 shows hair flowing to one side. Seed 3 is more like hair naturally falling to one shoulder than being deliberately gathered. Results are intermediate between side-gathered and ponytail with slightly lower precision.
Group D Summary
| Condition | Prompt | Accuracy | Stability (out of 3) | Side Effects | Rating |
|---|
| D01 | wavy hair | ○ | 3/3 | None | ★★★ |
| D02 | curly hair | ○ | 3/3 | Minor (outfit change) | ★★★ |
| D03 | afro | ○ | 3/3 | Moderate (skin tone change) | ★★ |
| D04 | dreadlocks | ○ | 3/3 | Minor (outfit/hair color change) | ★★ |
| D05 | side-gathered hair | △ | 2/3 | Minor | ★ |
E. State-Based (3 conditions)
E01: hair down and natural
1girl, 32yo japanese actress, hair down and natural, slightly uncombed-looking, standing, facing camera, upper body, simple white background, soft studio lighting
Observation: 3 out of 3 reproduce naturally worn-down hair. Compared to control, it falls more casually without much styling. Seed 1 is medium, seed 2 is longer — some length variation. Seed 2 changes outfit to a camisole. Difference from control is small.
E02: hair slightly disheveled
1girl, 32yo japanese actress, hair slightly disheveled, like after a long rehearsal or tired afternoon, standing, facing camera, upper body, simple white background, soft studio lighting
Observation: 3 out of 3 reproduce disheveled hair. Hair falling across the face and uneven flow are visible. Seed 2 has a wet texture, seed 3 pairs with a tank top giving a “sweaty” impression. The outfit exposure increase is a noticeable side effect.
E03: tousled bedhead hair
1girl, 32yo japanese actress, tousled bedhead hair, slightly tangled and uncombed, standing, facing camera, upper body, simple white background, soft studio lighting
Observation: 3 out of 3 reproduce heavily disheveled bedhead. More disordered than E02, with the entire hair wet and tangled. All seeds 1-3 change outfits to tank tops or camisoles — a prominent context-driven outfit change tied to “just woke up.” The messy hair itself is stably reproduced.
Lab Director Comment: bedhead making the outfit a camisole makes sense — it’s reading the “just woke up” context. More of a feature than a bug, really.
Group E Summary
| Condition | Prompt | Accuracy | Stability (out of 3) | Side Effects | Rating |
|---|
| E01 | hair down and natural | △ | 3/3 | Minor (outfit change) | ★ |
| E02 | hair slightly disheveled | ○ | 3/3 | Moderate (outfit exposure increase) | ★★ |
| E03 | tousled bedhead hair | ○ | 3/3 | Major (outfit exposure increase) | ★ |
Summary
Full Condition Summary
| Group | Condition | Prompt | Accuracy | Stability (out of 3) | Side Effects | Rating |
|---|
| A | A00 | (none) | — | — | — | — |
| A | A01 | long hair | ○ | 3/3 | None | ★★★ |
| A | A02 | short hair | ○ | 3/3 | None | ★★★ |
| A | A03 | medium hair | ○ | 3/3 | None | ★★ |
| A | A04 | short bob cut | ○ | 3/3 | None | ★★★ |
| B | B01 | ponytail | ○ | 3/3 | None | ★★★ |
| B | B02 | high ponytail | ○ | 3/3 | None | ★★★ |
| B | B03 | side ponytail | ○ | 3/3 | Minor | ★★ |
| B | B04 | bun | ○ | 3/3 | Moderate (Japanese clothing) | ★★ |
| B | B05 | messy bun | ○ | 3/3 | Minor | ★★ |
| B | B06 | updo | ○ | 3/3 | None | ★★★ |
| B | B07 | braid | ○ | 3/3 (count unstable) | None | ★★ |
| B | B08 | french braid | △ | 2/3 | Moderate | ★ |
| B | B09 | twin braids | ○ | 3/3 | None | ★★★ |
| B | B10 | twintails | ○ | 3/3 | Minor (younger appearance) | ★★ |
| C | C01 | bob cut | ○ | 3/3 | None | ★★★ |
| C | C02 | pixie cut | ○ | 3/3 | Minor | ★★★ |
| C | C03 | hime cut | △ | 1/3 | Minor | ★ |
| C | C04 | wolf cut | × | 1/3 | Major (wolf appearance) | − |
| C | C05 | layered hair | △ | 3/3 | Minor (butterfly appearance) | ★ |
| C | C06 | undercut | × | 0/3 | None | − |
| C | C07 | straight hair | ○ | 3/3 | Minor | ★★ |
| C | C08 | outward flip medium hair | △ | 2/3 | Moderate | ★ |
| D | D01 | wavy hair | ○ | 3/3 | None | ★★★ |
| D | D02 | curly hair | ○ | 3/3 | Minor | ★★★ |
| D | D03 | afro | ○ | 3/3 | Moderate (skin tone change) | ★★ |
| D | D04 | dreadlocks | ○ | 3/3 | Minor | ★★ |
| D | D05 | side-gathered hair | △ | 2/3 | Minor | ★ |
| E | E01 | hair down and natural | △ | 3/3 | Minor | ★ |
| E | E02 | hair slightly disheveled | ○ | 3/3 | Moderate (outfit exposure increase) | ★★ |
| E | E03 | tousled bedhead hair | ○ | 3/3 | Major (outfit exposure increase) | ★ |
Recommended Prompts
Reliably usable hair style prompts (★★★):
ponytail — No side effects, 3/3 stability. The most stable arrangement promptshort hair / long hair — Basic length control. No side effectsbob cut / short bob cut — Bob styles reproduce with high accuracybraid / twin braids — Braided styles reproduce even the braid structure clearlypixie cut — Even ultra-short styles reproduce stablyhigh ponytail / updo — Tie position height is controllablewavy hair / curly hair — Stepwise control of texture is possible
Prompts requiring caution:
bun — Tends to trigger outfit changes to Japanese clothingtwintails — Subject tends to look youngerbedhead / disheveled — Outfit shifts toward more exposure
Prompts to avoid:
wolf cut — Fatal side effect of wolf illustrations appearingundercut — The shaved section isn’t reproduced (outputs as short bob instead)
Lab Director Comment: Testing 30 styles and getting 10 at ★★★ is a solid haul. ponytail taking the top spot with zero side effects makes total sense. As for wolf cut summoning actual wolves… the model’s being a bit too literal, I guess.
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