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Virtual Journal for Biomedical Optics

Virtual Journal for Biomedical Optics


  • Editor: Gregory W. Faris
  • Vol. 2, Iss. 1 — Jan. 19, 2007

A new image calibration system in digital colposcopy

Wenjing Li, Marcelo Soto-Thompson, and Ulf Gustafsson  »View Author Affiliations

Optics Express, Vol. 14, Issue 26, pp. 12887-12901 (2006)

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Colposcopy is a primary diagnostic method used to detect cancer and precancerous lesions of the uterine cervix. During the examination, the metaplastic and abnormal tissues exhibit different degrees of whiteness (acetowhitening effect) after applying a 3%–5% acetic acid solution. Colposcopists evaluate the color and density of the acetowhite tissue to assess the severity of lesions for the purpose of diagnosis, telemedicine, and annotation. However, the color and illumination of the colposcopic images vary with the light sources, the instruments and camera settings, as well as the clinical environments. This makes assessment of the color information very challenging even for an expert. In terms of developing a Computer-Aided Diagnosis (CAD) system for colposcopy, these variations affect the performance of the feature extraction algorithm for the acetowhite color. Non-uniform illumination from the light source is also an obstacle for detecting acetowhite regions, lesion margins, and anatomic features. There fore, in digital colposcopy, it is critical to map the color appearance of the images taken with different colposcopes into one standard color space with normalized illumination. This paper presents a novel image calibration technique for colposcopic images. First, a specially designed calibration unit is mounted on the colposcope to acquire daily calibration data prior to performing subject examinations. The calibration routine is fast, automated, accurate and reliable. We then use our illumination correction algorithm and a color calibration algorithm to calibrate the exam data. In this paper we describe these techniques and demonstrate their applications in clinical studies.

© 2006 Optical Society of America

OCIS Codes
(100.0100) Image processing : Image processing
(110.0110) Imaging systems : Imaging systems
(150.0150) Machine vision : Machine vision
(170.0170) Medical optics and biotechnology : Medical optics and biotechnology
(330.0330) Vision, color, and visual optics : Vision, color, and visual optics

ToC Category:
Medical Optics and Biotechnology

Original Manuscript: September 1, 2006
Revised Manuscript: November 27, 2006
Manuscript Accepted: November 29, 2006
Published: December 22, 2006

Virtual Issues
Vol. 2, Iss. 1 Virtual Journal for Biomedical Optics

Wenjing Li, Marcelo Soto-Thompson, and Ulf Gustafsson, "A new image calibration system in digital colposcopy," Opt. Express 14, 12887-12901 (2006)

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