Two-photon fluorescence (TPF) and second harmonic generation (SHG) microscopy provide direct visualization of the skin dermal fibers in vivo. A typical method for analyzing TPF/SHG images involves averaging the image intensity and therefore disregarding the spatial distribution information. The goal of this study is to develop an algorithm to document age-related effects of the dermal matrix. TPF and SHG images were acquired from the upper inner arm, volar forearm, and cheek of female volunteers of two age groups: 20 to 30 and 60 to 80 years of age. The acquired images were analyzed for parameters relating to collagen and elastin fiber features, such as orientation and density. Both collagen and elastin fibers showed higher anisotropy in fiber orientation for the older group. The greatest difference in elastin fiber anisotropy between the two groups was found for the upper inner arm site. Elastin fiber density increased with age, whereas collagen fiber density decreased with age. The proposed analysis considers the spatial information inherent to the TPF and SHG images and provides additional insights into how the dermal fiber structure is affected by the aging process.
It is known that effectiveness of acne treatment increases when the lesions are detected earlier, before they could progress into mature wound-like lesions, which lead to scarring and discoloration. However, little is known about the evolution of acne from early signs until after the lesion heals. In this work we computationally characterize the evolution of inflammatory acne lesions, based on analyzing cross-polarized images that document acne-prone facial skin over time. Taking skin images over time, and being able to follow skin features in these images present serious challenges,
due to change in the appearance of skin, difficulty in repositioning the subject, involuntary movement such as breathing.
A computational technique for automatic detection of lesions by separating the background normal skin from the acne lesions, based on fitting Gaussian distributions to the intensity histograms, is presented. In order to track and quantify the evolution of lesions, in terms of the degree of progress or regress, we designed a study to capture facial skin images from an acne-prone young individual, followed over the course of 3 different time points. Based on the behavior of the lesions between two consecutive time points, the automatically detected lesions are classified in four categories: new lesions, resolved lesions (i.e. lesions that disappear completely), lesions that are progressing, and lesions that are regressing (i.e. lesions in the process of healing). The classification our methods achieve correlates well with visual inspection of a trained human grader.
The activity of certain bacteria in skin is known to correlate to the presence of porphyrins. In particular
the presence of coproporphyrin produced by P.acnes inside plugged pores has been correlated to acne vulgaris.
Another porphyrin encountered in skin is protoporphyrin IX, which is produced by the body in the pathway for
production of heme.
In the present work, a fluorescence spectroscopy system was developed to measure the characteristic spectrum
and quantify the two types of porphyrins commonly present in human facial skin. The system is comprised of
a Xe lamp both for fluorescence excitation and broadband light source for diffuse reflectance measurements. A
computer-controlled filter wheel enables acquisition of sequential spectra, first excited by blue light at 405 nm
then followed by the broadband light source, at the same location. The diffuse reflectance spectrum was used
to correct the fluorescence spectrum due to the presence of skin chromophores, such as blood and melanin. The
resulting fluorescence spectra were employed for the quantification of porphyrin concentration in a population of
healthy subjects. The results show great variability on the concentration of these porphyrins and further studies
are being conducted to correlate them with skin conditions such as inflammation and acne vulgaris.
Nowadays, documenting the face appearance through imaging is prevalent in skin research, therefore detection
and quantitative assessment of the degree of facial wrinkling is a useful tool for establishing an objective baseline
and for communicating benefits to facial appearance due to cosmetic procedures or product applications. In this
work, an algorithm for automatic detection of facial wrinkles is developed, based on estimating the orientation and
the frequency of elongated features apparent on faces. By over-filtering the skin texture image with finely tuned
oriented Gabor filters, an enhanced skin image is created. The wrinkles are detected by adaptively thresholding
the enhanced image, and the degree of wrinkling is estimated based on the magnitude of the filter responses.
The algorithm is tested against a clinically scored set of images of periorbital lines of different severity and we
find that the proposed computational assessment correlates well with the corresponding clinical scores.
KEYWORDS: 3D image processing, Databases, Detection and tracking algorithms, Principal component analysis, Object recognition, Image segmentation, Monte Carlo methods, Machine vision, 3D vision, Computer vision technology
Texture as a surface representation is the subject of a wide body of computer vision and computer graphics literature. While texture is always associated with a form of repetition in the image, the repeating quantity may vary. The texture may be a color or albedo variation as in a checkerboard, a paisley print or zebra stripes. Very often in real-world scenes, texture is instead due to a surface height variation, e.g. pebbles, gravel, foliage and any rough surface. Such surfaces are referred to here as 3D textured surfaces. Standard texture recognition algorithms are not appropriate for 3D textured surfaces because the appearance of these surfaces changes in a complex manner with viewing direction and illumination direction. Recent methods have been developed for recognition of 3D textured surfaces using a database of surfaces observed under varied imaging parameters. One of these methods is based on 3D textons obtained using K-means clustering of multiscale feature vectors. Another method uses eigen-analysis originally developed for appearance-based object recognition. In this work we develop a hybrid approach that employs both feature grouping and dimensionality reduction. The method is tested using the Columbia-Utrecht texture database and provides excellent recognition rates. The method is compared with existing recognition methods for 3D textured surfaces. A direct comparison is facilitated by empirical recognition rates from the same texture data set. The current method has key advantages over existing methods including requiring less prior information on both the training and novel images.
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