title: Direct curvature correction for noncontact imaging modalities applied to multispectral imaging.
abstract: Noncontact optical imaging of curved objects can result in strong artifacts due to the object's shape, leading to curvature biased intensity distributions. This artifact can mask variations due to the object's optical properties, and makes reconstruction of optical/physiological properties difficult. In this work we demonstrate a curvature correction method that removes this artifact and recovers the underlying data, without the necessity of measuring the object's shape. This method is applicable to many optical imaging modalities that suffer from shape-based intensity biases. By separating the spatially varying data (e.g., physiological changes) from the background signal (dc component), we show that the curvature can be extracted by either averaging or fitting the rows and columns of the images. Numerical simulations show that our method is equivalent to directly removing the curvature, when the object's shape is known, and accurately recovers the underlying data. Experiments on phantoms validate the numerical results and show that for a given image with 16.5% error due to curvature, the method reduces that error to 1.2%. Finally, diffuse multispectral images are acquired on forearms in vivo. We demonstrate the enhancement in image quality on intensity images, and consequently on reconstruction results of blood volume and oxygenation distributions.
authors.affiliation: National Institutes of Health, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Section on Analytical and Functional Biophotonics (PPITS/SAFB), Bethesda, Maryland 20892, USA. kainersj@mail.nih.gov
authors.forename: Jana M
authors.initials: JM
authors.lastname: Kainerstorfer
authors.forename: Franck
authors.initials: F
authors.lastname: Amyot
authors.forename: Martin
authors.initials: M
authors.lastname: Ehler
authors.forename: Moinuddin
authors.initials: M
authors.lastname: Hassan
authors.forename: Stavros G
authors.initials: SG
authors.lastname: Demos
authors.forename: Victor
authors.initials: V
authors.lastname: Chernomordik
authors.forename: Christoph K
authors.initials: CK
authors.lastname: Hitzenberger
authors.forename: Amir H
authors.initials: AH
authors.lastname: Gandjbakhche
authors.forename: Jason D
authors.initials: JD
authors.lastname: Riley
mesh_terms: D000465:Algorithms; D005542:Forearm / Q000033:anatomy & histology*; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013057:Spectrum Analysis / Q000379:methods*
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