Document Detail


Effect of image quality, color, and format on the measurement of retinal vascular fractal dimension.
MedLine Citation:
PMID:  20554610     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
PURPOSE: Fractal dimension of retinal vasculature is a global summary measure of retinal vascular network pattern and geometry. This study was conducted to examine the effect of variations in image color, brightness, focus, contrast, and format on the measurement of retinal vascular fractal dimension.
METHODS: A set of 30 retinal images from the Blue Mountains Eye Study was used for a series of experiments by varying brightness, focus (blur), contrast, and color (color versus monochrome). The original and the modified images were graded for fractal dimension (D(f)) using dedicated retinal imaging software (IRIS-Fractal). A further set of 20 grayscale images was used to compare image format (.jpg versus .tif) with regard to the resultant D(f) and processing time.
RESULTS: The mean D(f) of original images in this sample was 1.454. Compared with the original set of images, variations in brightness, focus, contrast, and color affected the measurements to a small to moderate degree (Pearson correlation coefficient, r, ranged from 0.47 to 0.97). Very dark or blurry images resulted in a substantially lower estimate of D(f). Monochrome images were also consistently associated with lower D(f) compared with that obtained from color images. Using .jpg or .tif image formats did not affect the measurement or the time needed to process and measure D(f).
CONCLUSIONS: Variations in image brightness, focus, and contrast can significantly affect the measurement of retinal vascular fractals. Standardization of image parameters and consistent use of either monochrome or color images would reduce measurement noise and enhance the comparability of the results.
Authors:
Alan Wainwright; Gerald Liew; George Burlutsky; Elena Rochtchina; Yong Ping Zhang; Wynne Hsu; Janice MongLi Lee; Tien Yin Wong; Paul Mitchell; Jie Jin Wang
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2010-06-16
Journal Detail:
Title:  Investigative ophthalmology & visual science     Volume:  51     ISSN:  1552-5783     ISO Abbreviation:  Invest. Ophthalmol. Vis. Sci.     Publication Date:  2010 Nov 
Date Detail:
Created Date:  2010-10-28     Completed Date:  2010-12-07     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  7703701     Medline TA:  Invest Ophthalmol Vis Sci     Country:  United States    
Other Details:
Languages:  eng     Pagination:  5525-9     Citation Subset:  IM    
Affiliation:
Department of Ophthalmology, Centre for Vision Research, Westmead Millennium Institute, University of Sydney, Sydney, Australia;
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MeSH Terms
Descriptor/Qualifier:
Color
Fractals*
Humans
Image Enhancement*
Image Processing, Computer-Assisted / standards*
Photography*
Reproducibility of Results
Retinal Vessels / anatomy & histology*

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


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