Document Detail

Brightness, contrast, and color balance of digital versus film retinal images in the age-related eye disease study 2.
MedLine Citation:
PMID:  18421079     Owner:  NLM     Status:  MEDLINE    
PURPOSE: To analyze brightness, contrast, and color balance of digital versus film retinal images in a multicenter clinical trial, to propose a model image from exemplars, and to optimize both image types for evaluation of age-related macular degeneration (AMD). METHODS: The Age-Related Eye Disease Study 2 (AREDS2) is enrolling subjects from 90 clinics, with three quarters of them using digital and one quarter using film cameras. Image brightness (B), contrast (C), and color balance (CB) were measured with three-color luminance histograms. First, the exemplars (film and digital) from expert groups were analyzed, and an AMD-oriented model was constructed. Second, the impact of B/C/CB on the appearance of typical AMD abnormalities was analyzed. Third, B/C/CB in AREDS2 images were compared between film (156 eyes) and digital (605 eyes), and against the model. Fourth, suboptimal images were enhanced by adjusting B/C/CB to bring them into accord with model parameters. RESULTS: Exemplar images had similar brightness, contrast, and color balance, supporting an image model. Varying a specimen image through a wide range of B/C/CB revealed greatest contrast of drusen and pigment abnormalities against normal retinal pigment epithelium with the model parameters. AREDS2 digital images were more variable than film, with lower correspondence to our model. Ten percent of digital were too dim and 19% too bright (oversaturated), versus 1% and 4% of film, respectively. On average, digital had lower green channel contrast (giving less retinal detail) than film. Overly red color balance (weaker green) was observed in 23% of digital versus 8% of film. About half of digital (but fewer film) images required enhancement before AMD grading. After optimization of both image types, AREDS2 image quality was judged as good as that in AREDS (all film). CONCLUSIONS: A histogram-based model, derived from exemplars, provides a pragmatic guide for image analysis and enhancement. In AREDS2, the best digital images matched the best film. Overall, however, digital provided lower contrast of retinal detail. Digital images taken with higher G-to-R ratio showed better brightness and contrast management. Optimization of images in the multicenter study helps standardize documentation of AMD ( NCT00345176).
Larry D Hubbard; Ronald P Danis; Michael W Neider; Dennis W Thayer; Hugh D Wabers; James K White; Anthony J Pugliese; Michael F Pugliese;
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Publication Detail:
Type:  Clinical Trial; Comparative Study; Journal Article; Multicenter Study; Research Support, N.I.H., Extramural     Date:  2008-04-17
Journal Detail:
Title:  Investigative ophthalmology & visual science     Volume:  49     ISSN:  1552-5783     ISO Abbreviation:  Invest. Ophthalmol. Vis. Sci.     Publication Date:  2008 Aug 
Date Detail:
Created Date:  2008-07-28     Completed Date:  2008-08-12     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  7703701     Medline TA:  Invest Ophthalmol Vis Sci     Country:  United States    
Other Details:
Languages:  eng     Pagination:  3269-82     Citation Subset:  IM    
Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, Madison, Wisconsin 53711-1068, USA.
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MeSH Terms
Aged, 80 and over
Macular Degeneration / diagnosis*
Middle Aged
Photography / methods,  standards*
Retina / pathology*
Signal Processing, Computer-Assisted*
Grant Support
HHSN 260-2006-00003C//PHS HHS

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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