Front-facing cameras have lower resolution than rear-facing cameras on virtually every smartphone made since 2020. That single hardware difference means the technique you use to photograph your scalp directly affects the quality of data you feed into any AI density analysis tool, including myhairline.ai.
This guide compares the selfie (front-facing) and mirror (rear-facing reflected) techniques zone by zone, so you can pick the method that produces the most reliable density data for each area of your head.
Why Camera Choice Matters for Density Tracking
The rear camera on a modern smartphone typically captures at 48MP or higher. The front-facing selfie camera usually tops out at 12MP. That 4x resolution difference means the rear camera resolves individual hair shafts more clearly, giving AI algorithms more data to work with when calculating density.
Resolution is not the only factor. Lens distortion, autofocus speed, and dynamic range also differ between the two cameras. Here is how they compare for hair tracking specifically:
| Factor | Front Camera (Selfie) | Rear Camera (Mirror) |
|---|---|---|
| Resolution | 12MP typical | 48-200MP typical |
| Lens distortion | Higher (wide angle) | Lower (standard angle) |
| Autofocus for close-up | Slower, less precise | Faster, more precise |
| Angle control (crown) | Poor, awkward arm position | Good, natural position |
| Angle control (hairline) | Good, direct aim | Moderate, requires mirror alignment |
| Consistency across sessions | Moderate | High (with floor markings) |
Zone-by-Zone Technique Recommendations
Hairline and Temples
Best method: Rear camera with timer or voice trigger.
You can see your hairline directly, so a mirror is not necessary. Set your phone on a stable surface at forehead height, activate a 3-second timer, and position your hairline in the frame. The rear camera captures the recession line with enough detail for accurate Norwood staging.
If you prefer the front camera for convenience, it works acceptably for the hairline because the target area is close to the lens. Just be aware that wide-angle distortion on the front camera can exaggerate temple recession slightly.
Crown and Vertex
Best method: Rear camera aimed at a bathroom mirror.
This is where the mirror technique wins decisively. Trying to selfie your own crown requires bending your arm over your head at an awkward angle, which produces inconsistent framing and distance every time you shoot.
Instead, stand with your back to the mirror. Hold your phone over your head with the rear camera pointing at the mirror. You can see the screen to frame your crown accurately, and the rear camera captures the higher resolution image.
Using this method produces roughly 40% more consistent angle control compared to a front-facing crown selfie, based on test comparisons across multiple phone models.
Mid-Scalp (Between Hairline and Crown)
Best method: Rear camera with mirror, top-down angle.
The mid-scalp is the hardest zone to photograph consistently because it requires a steep overhead angle. The mirror technique lets you hold the phone above your head while checking framing in the reflection. Mark your standing position with tape for repeatability.
Side Profiles
Best method: Mirror technique or second person.
Side profiles show temporal recession and donor area density. A mirror lets you capture the rear camera image of your profile while checking framing live. If someone else can take the photo for you, that produces even more consistent results.
Setting Up a Repeatable Mirror Station
Consistency is the most important factor in tracking data quality. A 5-minute setup creates a permanent photo station:
Step 1: Choose Your Mirror
Use a wall-mounted bathroom mirror. Medicine cabinet mirrors work well because they are at a fixed height. Avoid handheld mirrors since they introduce position variability.
Step 2: Mark Your Floor Position
Place a small piece of tape on the floor where your feet go. This fixes your distance from the mirror across every session. Typical distance is 50-70 cm from the mirror surface.
Step 3: Mark Your Phone Position
Put a small piece of tape on the mirror frame at the height where your phone appears in the reflection when held correctly. This gives you a vertical reference point.
Step 4: Standardize Lighting
Use the same light source every time. Overhead bathroom lighting is the most common and most consistent option. Avoid photographing with a window behind you, as changing daylight creates exposure variation.
For more on photo consistency, see our full guide on consistent hair loss progress photos.
Common Mistakes with Each Technique
Selfie Mistakes
- Holding the phone too close. Front cameras have minimum focus distances. Below about 20 cm, the image blurs and density calculation accuracy drops.
- Using portrait mode. Portrait mode applies artificial background blur that destroys hair detail at the edges of the frame. Always shoot in standard photo mode.
- Inconsistent arm extension. Your arm length stays the same, but wrist angle and shoulder height change. This shifts framing between sessions.
Mirror Mistakes
- Dirty mirror surface. Smudges and water spots reduce contrast, making it harder for AI to distinguish individual hairs. Clean the mirror before each session.
- Mirror reflection of flash. Never use flash with a mirror technique. The flash bounces back and blows out the image. Use ambient room lighting only.
- Changing zoom level. Lock your camera to 1x zoom. Pinch-to-zoom uses digital zoom, which degrades resolution rather than improving it.
Matching Your Technique to myhairline.ai
myhairline.ai's analysis works with both selfie and mirror-based photos. The key requirement is sufficient resolution and consistent framing. For hairline analysis specifically, a direct front-facing view (either selfie or rear camera with timer) provides the facial landmark references the Norwood staging algorithm needs.
For crown density tracking, the mirror technique with the rear camera provides the best data quality. The higher resolution captures more hair shaft detail, which improves the reliability of density change measurements between sessions.
For camera-specific settings that optimize tracking accuracy, see our guide on optimal camera settings for tracking.
Start Tracking with the Right Technique
Set up your mirror station, take your first set of zone-specific photos, and upload them to myhairline.ai/analyze for a free baseline analysis. Consistent technique from day one means every future data point will be comparable to your first.
Medical disclaimer: This article is for informational purposes only and does not constitute medical advice. Hair loss tracking tools provide objective measurements but do not diagnose medical conditions. Consult a dermatologist for clinical evaluation.