Head hair

Scalp hair morphology: color, texture, pattern, density, hairline shape, and balding patterns. Expands the existing 3-field analysis schema (color/texture/pattern) into a comprehensive trichology-grounded vocabulary. The Andre Walker texture classification (1A-4C) is the de-facto reference for hair texture across populations; the Hamilton-Norwood (male) and Ludwig (female) scales are the canonical balding-pattern references.

Dimensions

• Hair color

  photo-observable

  categorical · hair_color_qualitative

  Predominant natural hair color, where determinable. Visibly dyed hair should be flagged via grooming-state metadata.

  Aligned with trichology and pigment-genetics literature (MC1R / TYR / OCA polymorphism studies).

  Valid values (12)

  • blackBlack— Very dark hair appearing black under normal lighting; high eumelanin.
  • dark_brownDark brown— Distinctly brown but darker than medium-brown.
  • medium_brownMedium brown— Standard brown hair.
  • light_brownLight brown— Light-brown to caramel range.
  • blonde_darkDark blonde— Dark blonde / dirty blonde.
  • blonde_mediumMedium blonde— Standard blonde.
  • blonde_platinumPlatinum / very light blonde— Very light blonde, often near-white. Often dyed in adults.
  • red_auburnRed / auburn— Red, auburn, or copper. High pheomelanin; correlated with MC1R variants.
  • grayGray— Visibly graying hair, mixed pigmented and unpigmented.
  • whiteWhite— Predominantly unpigmented hair.
  • mixed_uniqueMixed / unique— Multiple distinct natural colors (e.g. natural ombre with sun-lightened tips).
  • dyed_visibleDyed (native color uncertain)— Visible dye job; native color cannot be reliably inferred.

• Hair texture (Andre Walker)

  photo-observable

  categorical · andre_walker_1990s

  Andre Walker hair-texture classification covering the spectrum from straight (Type 1) to coily (Type 4), with subdivisions A-C within each numbered type.

  The Andre Walker hair-typing system (developed in the 1990s for Oprah Winfrey's stylist and subsequently adopted broadly in trichology and beauty-industry literature).

  Valid values (13)

  • 1A_straight_fine1A — straight, fine— Stick-straight, very fine; minimal body.
  • 1B_straight_medium1B — straight, medium— Straight with medium body.
  • 1C_straight_coarse1C — straight, coarse— Straight, thick, coarse strands.
  • 2A_wavy_fine2A — wavy, fine— Loose S-waves; fine texture.
  • 2B_wavy_medium2B — wavy, medium— Defined S-waves; medium texture.
  • 2C_wavy_coarse2C — wavy, coarse— Strong S-waves transitioning to ringlets; coarse.
  • 3A_curly_loose3A — curly, loose ringlets— Loose, soft ringlets; well-defined curl.
  • 3B_curly_springy3B — curly, springy— Tighter, springy curls; corkscrew shape.
  • 3C_curly_tight3C — curly, tight corkscrew— Tight corkscrew curls; densely packed.
  • 4A_coily_S4A — coily, S-pattern— Defined small S-pattern coils.
  • 4B_coily_Z4B — coily, Z-pattern— Sharp angular Z-pattern coils.
  • 4C_coily_tight4C — coily, tightly packed— Tightly packed coils with little visible pattern definition; high shrinkage.
  • covered_unclearCovered / unclear— Hair covered by head covering or styling that prevents texture assessment.

• Hair density

  photo-observable

  ordinal · hair_density_qualitative

  Density of native scalp hair when ungroomed.

  Aligned with trichology descriptors of follicular density (typical 200-300 follicles/cm² scalp).

  Valid values (5)

  • sparseSparse— Visible scalp through hair throughout most of the head.
  • thinThin— Some visible scalp; reduced density.
  • averageAverage— Standard density; minimal visible scalp.
  • thickThick— Above-average density.
  • very_thickVery thick— Pronounced density; voluminous appearance.

• Hairline shape

  photo-observable

  categorical · hairline_shape_qualitative

  Shape of the anterior hairline.

  Aligned with hair-transplant-surgery descriptors of hairline morphology.

  Valid values (5)

  • straightStraight— Approximately horizontal hairline across the forehead.
  • roundedRounded— Smooth curve hairline; no peaks.
  • widows_peakWidow's peak— V-shaped point at the midline of the hairline.
  • m_shape_temporal_recessionM-shape (temporal recession)— Bilateral temporal recession creating an M-shape; common male-pattern feature.
  • uneven_asymmetricUneven / asymmetric— Notable left-right asymmetry.

• Hairline position (anterior)

  photo-observable

  ordinal · hairline_position_qualitative

  Vertical position of the anterior hairline.

  Aligned with hair-transplant-surgery descriptors of hairline-height assessment.

  Valid values (4)

  • lowLow— Hairline sits low on the forehead; reduced visible forehead.
  • averageAverage— Standard hairline position.
  • highHigh— Hairline sits high; tall visible forehead.
  • recededReceded— Recession beyond high-normal; balding-pattern signs visible.

• Balding pattern (Hamilton-Norwood, male)

  photo-observable

  ordinal · hamilton_norwood

  Hamilton-Norwood classification of male-pattern hair loss. Applies primarily to subjects with apparent male physiognomy.

  Hamilton JB (1951). Patterned loss of hair in man: types and incidence. Annals of the New York Academy of Sciences, 53. Norwood OT (1975). Male pattern baldness: classification and incidence. Southern Medical Journal, 68(11).

  Valid values (9)

  • type_I_no_lossType I — no recession— No hair loss visible.
  • type_II_minimal_temporalType II — minimal temporal recession
  • type_III_moderate_temporalType III — moderate temporal recession— Earliest stage commonly classified as balding.
  • type_III_vertexType III vertex — vertex thinning
  • type_IV_advanced_temporal_vertexType IV — advanced temporal recession + vertex thinning
  • type_V_loss_meetingType V — frontal and vertex loss approaching
  • type_VI_loss_mergedType VI — frontal and vertex loss merged
  • type_VII_advancedType VII — most advanced— Only horseshoe band of hair remaining around sides and back.
  • not_applicable_or_femaleNot applicable— Subject not in male-pattern population, or no balding.

• Balding pattern (Ludwig, female)

  photo-observable

  ordinal · ludwig_classification

  Ludwig classification of female-pattern hair loss. Applies primarily to subjects with apparent female physiognomy.

  Ludwig E (1977). Classification of the types of androgenetic alopecia (common baldness) occurring in the female sex. British Journal of Dermatology, 97(3): 247-254.

  Valid values (5)

  • no_lossNo loss
  • ludwig_ILudwig I — perceptible thinning of the crown— Anterior hairline preserved.
  • ludwig_IILudwig II — pronounced central thinning— Crown thinning pronounced; anterior hairline preserved.
  • ludwig_IIILudwig III — full central baldness— Crown fully bald; anterior hairline preserved.
  • not_applicable_or_maleNot applicable— Subject not in female-pattern population, or no balding.

• Graying pattern

  photo-observable

  categorical · graying_pattern_qualitative

  Pattern and extent of visible gray / white hair.

  Aligned with descriptors used in trichology and pigment-aging literature.

  Valid values (7)

  • noneNone— No visible gray hairs.
  • scattered_fewScattered few— A few isolated gray hairs visible.
  • temple_concentratedTemple-concentrated— Graying concentrated at temples; common early-graying pattern.
  • salt_and_pepperSalt and pepper— Mixed gray and pigmented hair throughout; often ~50/50.
  • predominantly_grayPredominantly gray
  • fully_gray_whiteFully gray / white
  • dyed_likelyDyed (graying suggested)— Visible dye job that likely covers gray; native graying state not directly observable.