Split Scalp Comparison: myhairline.ai's Signature Before-After Feature
Split-scalp comparison removes the 15 to 20% of apparent change in standard before-after comparisons that is due to angle variation, giving you the most accurate visual representation of your actual density improvement. This feature uses facial landmark anchoring to align two photos from different tracking sessions on the same anatomical reference points.
This guide covers how the split-scalp comparison works, how to take photos that produce the best comparisons, and how to use the results with your dermatologist and for personal motivation.
Why Standard Before-After Photos Are Misleading
Standard before-after photos of hair loss treatment are notoriously unreliable. Even a small change in camera angle, lighting direction, or head tilt can make identical hair density appear dramatically different.
Sources of Error in Standard Photos
| Variable | Effect on Appearance | Magnitude of Distortion |
|---|---|---|
| Camera angle (5-degree tilt) | Can expose or hide scalp | 10-15% apparent density change |
| Lighting direction | Overhead = thinner look; side = fuller | 15-20% apparent density change |
| Hair wetness | Wet hair clumps and exposes scalp | 20-30% apparent density change |
| Hair styling | Blow-dried volume vs flat | 15-25% apparent density change |
| Camera distance | Closer = more scalp detail visible | 10-15% apparent density change |
A patient with zero actual density change could create a "before-after" pair that shows either dramatic improvement or dramatic worsening simply by adjusting these variables. This is why social media before-after photos are so misleading, and why clinical density measurement matters more than visual impressions.
How Split-Scalp Comparison Works
The myhairline.ai split-scalp comparison addresses these variables through a multi-step alignment process.
Step 1: Facial Landmark Detection
When you upload a photo, the AI identifies stable facial landmarks: the position of the eyes, the bridge of the nose, the ears, and the forehead hairline anchor points. These landmarks do not change between sessions, making them reliable reference points for alignment.
Step 2: Geometric Normalization
Using the detected landmarks, the system normalizes both photos to the same geometric orientation. If your head was tilted slightly left in the "before" photo and slightly right in the "after" photo, the system corrects for this difference before generating the comparison.
Step 3: Region Mapping
The scalp is divided into clinical regions (frontal, mid-scalp, vertex, temporal) using the normalized landmark positions. Each region in the "before" photo maps to the identical region in the "after" photo.
Step 4: Split Overlay Generation
The system generates the comparison in one of two formats:
Slider comparison: Both photos overlaid, with a draggable slider that reveals one or the other. This format is best for seeing density changes in specific areas.
Side-by-side split: The "before" photo shows the left half, the "after" photo shows the right half, aligned at the midline. This format provides an instant visual comparison.
How to Take Photos for Optimal Split Comparisons
The alignment system corrects for moderate angle variation, but better input photos produce sharper comparisons. Follow these guidelines for the best results.
Lighting
Use consistent lighting between sessions. The best option is indirect natural daylight from a window, positioned to your side (not overhead). Overhead lighting exaggerates thinning. Direct flash creates harsh shadows.
If natural light is not available, use the same artificial light source in the same position each time. Bathroom lighting works if you always use the same bathroom.
Head Position
Face the camera directly with your chin level. For vertex (crown) photos, tilt your head forward to a consistent angle. Using a reference point (like looking at a specific spot on the floor) helps maintain the same tilt each session.
Hair Preparation
Clean, towel-dried hair with no products is the standard. Apply no styling products, hair fibers, dry shampoo, or concealers. Part your hair the same way each time, or do not part it at all.
Camera Distance
Maintain a consistent distance from the camera. Arm's length for a selfie or a fixed position (like a shelf or tripod) for front-facing photos. The closer the camera, the more scalp detail is visible, so consistency matters more than the specific distance.
Checklist for Each Session
| Item | Standard |
|---|---|
| Hair state | Clean, towel-dried, no products |
| Lighting | Same source and position as previous sessions |
| Head angle | Same tilt and facing direction |
| Camera distance | Same distance (arm's length or fixed position) |
| Hair part | Same part or no part |
| Time of day | Consistent (lighting varies by time) |
Using Split Comparisons with Your Dermatologist
Split-scalp comparisons are valuable additions to dermatology appointments because they provide visually aligned evidence that supplements your density score data.
Bring both data types. Show your dermatologist the density score trend (numerical) and the split-scalp comparison (visual). The numbers tell the clinical story. The visual comparison makes it immediately intuitive.
Highlight specific regions. If your split comparison shows improvement in the frontal zone but not the vertex, this regional data helps your dermatologist adjust your treatment protocol. Some treatments like finasteride (80 to 90% halt loss, 65% regrowth) and minoxidil (40 to 60% regrowth) may produce different regional responses.
Track post-transplant recovery. After FUE surgery (7 to 10 day recovery, 90 to 95% graft survival rate), split comparisons at 3, 6, 9, and 12 months provide a clear visual record of graft maturation. This is especially valuable given the shedding phase at months 1 to 3 that can be visually disconcerting without aligned comparison data.
Interpreting Your Split Comparison Results
When reviewing your split comparison, focus on these indicators:
Scalp visibility reduction. Less visible scalp in the "after" half indicates increased density or improved hair shaft thickness.
Hairline definition. Sharpening of the hairline boundary suggests effective treatment in the frontal zone.
Vertex coverage. Increased coverage at the crown is one of the most visible improvements in split comparisons.
Temporal density. Changes at the temples are subtle but visible in aligned comparisons, particularly for patients at Norwood stages 2 to 3 (requiring 800 to 2,200 grafts if pursuing transplant).
What to Expect at Different Timeframes
| Comparison Interval | What to Look For |
|---|---|
| 3 months | Stabilization; minimal visual change is normal |
| 6 months | First visible density improvements in responders |
| 9 months | Clear improvement visible in split comparison |
| 12 months | Full treatment effect visible; ideal for documentation |
For guidance on taking the best possible tracking photos, see our guide on taking consistent hair loss progress photos. To see examples of effective tracking documentation, visit the before-after tracking gallery.
Create Your First Split Comparison
You need two tracking sessions to generate a split comparison. Start with your first upload today, then track again in 4 to 6 weeks. After your second session, the split comparison feature shows you exactly what has changed, aligned to the same anatomical reference points.
Upload your first photo at myhairline.ai/analyze to begin building your comparison history.
Medical disclaimer: This article is for informational purposes only and does not constitute medical advice. Visual comparisons supplement but do not replace clinical assessment by a board-certified dermatologist. Individual results vary.