Intra- and inter-rater reliability of digital image analysis for skin color measurement

Marilyn Sommers, Barbara Beacham, Rachel Baker, Jamison Fargo

Research output: Contribution to journalArticlepeer-review

21 Scopus citations


Background: We determined the intra- and inter-rater reliability of data from digital image color analysis between an expert and novice analyst. Methods: Following training, the expert and novice independently analyzed 210 randomly ordered images. Both analysts used Adobe® Photoshop lasso or color sampler tools based on the type of image file. After color correction with Pictocolor® in camera software, they recorded L*a*b* (L*=light/dark; a*=red/green; b*=yellow/blue) color values for all skin sites. We computed intra-rater and inter-rater agreement within anatomical region, color value (L*, a*, b*), and technique (lasso, color sampler) using a series of one-way intra-class correlation coefficients (ICCs). Results: Results of ICCs for intra-rater agreement showed high levels of internal consistency reliability within each rater for the lasso technique (ICC ≥ 0.99) and somewhat lower, yet acceptable, level of agreement for the color sampler technique (ICC = 0.91 for expert, ICC = 0.81 for novice). Skin L*, skin b*, and labia L* values reached the highest level of agreement (ICC ≥ 0.92) and skin a*, labia b*, and vaginal wall b* were the lowest (ICC ≥ 0.64). Conclusion: Data from novice analysts can achieve high levels of agreement with data from expert analysts with training and the use of a detailed, standard protocol.

Original languageEnglish (US)
Pages (from-to)484-491
Number of pages8
JournalSkin Research and Technology
Issue number4
StatePublished - Nov 2013


  • Digital image analysis
  • Image analysis
  • Inter-rater reliability
  • Protocols
  • Skin color
  • Skin imaging


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