title: Evaluation of a digital food photography atlas used as portion size measurement aid in dietary surveys in Greece.
abstract: To evaluate how well respondents perceive digital images of food portions commonly consumed in Greece.
  
  
  
  The picture series was defined on the basis of usual dietary intakes assessed in earlier large-scale studies in Greece. The evaluation included 2218 pre-weighed actual portions shown to participants, who were subsequently asked to link each portion to a food picture. Mean differences between picture numbers selected and portions actually shown were compared using the Wilcoxon paired signed-rank test. The effect of personal characteristics on participants' selections was evaluated through unpaired t tests (sex and school years) or through Tukey-Kramer pairwise comparisons (age and food groups).
  
  
  
  Testing of participants' perception of digital food images used in the Greek national nutrition survey.
  
  
  
  Individuals (n 103, 61 % females) aged 12 years and over, selected on the basis of the target population of the Greek nutrition survey using convenience sampling.
  
  
  
  Individuals selected the correct or adjacent image in about 90 % of the assessments and tended to overestimate small and underestimate large quantities. Photographs of Greek traditional pies and meat-based pastry dishes led participants to perceive the amounts in the photos larger than they actually were. Adolescents were more prone to underestimating food quantities through the pictures.
  
  
  
  The digital food atlas appears generally suitable to be used for the estimation of average food intakes in large-scale dietary surveys in Greece. However, individuals who consistently consume only small or only large food portions may have biased perceptions in relation to others.
authors.affiliation: 1Department of Hygiene,Epidemiology and Medical Statistics,School of Medicine,National and Kapodistrian University of Athens,Athens,Greece.
authors.forename: Androniki
authors.initials: A
authors.lastname: Naska
authors.affiliation: 2Hellenic Health Foundation,Kaisareias 13 & Alexandroupoleos,GR-115 27 Athens,Greece.
authors.forename: Elisavet
authors.initials: E
authors.lastname: Valanou
authors.affiliation: 2Hellenic Health Foundation,Kaisareias 13 & Alexandroupoleos,GR-115 27 Athens,Greece.
authors.forename: Eleni
authors.initials: E
authors.lastname: Peppa
authors.affiliation: 2Hellenic Health Foundation,Kaisareias 13 & Alexandroupoleos,GR-115 27 Athens,Greece.
authors.forename: Michail
authors.initials: M
authors.lastname: Katsoulis
authors.affiliation: 3Department of Public and Administrative Health,National School of Public Health,Athens,Greece.
authors.forename: Anastasia
authors.initials: A
authors.lastname: Barbouni
authors.affiliation: 2Hellenic Health Foundation,Kaisareias 13 & Alexandroupoleos,GR-115 27 Athens,Greece.
authors.forename: Antonia
authors.initials: A
authors.lastname: Trichopoulou
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D004034:Diet Surveys; D005260:Female; D005502:Food; D006115:Greece; D006801:Humans; D008297:Male; D008875:Middle Aged; D010781:Photography; D064787:Portion Size; D012858:Size Perception; D011795:Surveys and Questionnaires; D055815:Young Adult
keywords: Digital photo database; HYDRIA; Portion size estimation