title: The diversity of the human hair colour assessed by visual scales and instrumental measurements. A worldwide survey.
abstract: OBJECTIVE
  To study (i) the diversity of the natural colour of the human hair through both visual assessment of hair tone levels and colorimetric measurements of hair strands collected from 2057 human male and female volunteers, from 23 regions of the world and (ii) the correlation between visual assessments and colorimetric measurements.
  
  
  METHODS
  Hair strands were analysed by a spectrocolorimeter under the L*, a*, b* referential system and scored in vivo by experts before sampling, through standardized visual reference scales based on a 1-10 range.
  
  
  RESULTS
  Results show that from a typological aspect, black or dark brown hairs largely predominate among studied ethnic groups, whereas Caucasian or derived populations exhibit the widest palette of medium to fair shades, partly explaining some past interbreeding among populations. Instrumental measurements clearly confirm that a given colour of a pigmented hair, at the exclusion of red hairs, is mostly governed by two components, L* and b*, from the L*, a*, b* reference system.
  
  
  CONCLUSIONS
  The comparisons between visual assessments and instrumental data show that these appear closely linked. Darker hairs show close or subtle variations in L*, a*, b* parameters, making their individual colour differentiation calling for technical improvements in colorimetric measurements. The latter are likely governed by other physical factors such as shape, diameter and shine.
authors: L'Oréal Research & Innovation, 11-13 rue Dora Maar 93400, Saint Ouen, France.
authors: I
authors: I
authors: Lozano
authors: L'Oréal Research & Innovation, 11-13 rue Dora Maar 93400, Saint Ouen, France.
authors: J B
authors: JB
authors: Saunier
authors: L'Oréal Research & Innovation, 11-13 rue Dora Maar 93400, Saint Ouen, France.
authors: S
authors: S
authors: Panhard
authors: L'Oréal Research & Innovation, 11-13 rue Dora Maar 93400, Saint Ouen, France.
authors: G
authors: G
authors: Loussouarn
mesh_terms: D003124:Colorimetry; D005260:Female; D006200:Hair Color; D006801:Humans; D008297:Male; D011795:Surveys and Questionnaires
keywords: hair colour; spectrocolorimetry; worldwide