Skin Reflectance Research Articles

Novel multi-spectral short-wave infrared imaging for assessment of human burn wound depth.

Burn depth determination is critical for patient care but is currently lacking accuracy. Recent animal studies showed that Short Wave Infrared (SWIR) imaging can distinguish between superficial and deep burns. This is a first human study correlating reflectance of multiple SWIR bands using a SWIR assessment tool (SWAT) with burn depth classifications by surgeons and histology. Burns and adjacent normal skin in 11 patients with thermal injuries were imaged with visual and narrow bands centred at 1200, 1650, 1940 and 2250 nm and biopsies were taken from select areas. Reflectance intensities for each band in 273 regions of interest (ROI) were divided by the normal skin reflectance and combined into three Reflectance Indices (RIs). In addition, burns in ROIs and biopsies were classified by five surgeons and three pathologists, respectively, as superficial partial, deep partial, or full thickness. Results show that for burn depth increase classified by the surgeons, reflectance increased at 1200 and 2250, decreased at 1940, and didn't change at 1650 nm. In contrast, all three RIs increase with burn depth and predict the deep and full depths ROIs representing operable regions (Area Under Curve >0.6507, p < 0.0001). Pathologists' classification matched surgeons' classification of burn category only in eight of 21 biopsies (38.1%), but reflectance at all bands and one RI for all deep partial and full thickness biopsies were larger than in non-biopsy normal and superficial partial thickness ROIs (p < 0.0118). In conclusion, multi-spectral imaging with a new SWAT is a promising approach for evaluation of burn wound depth.

An Accurate Non-contact Photoplethysmography via Active Cancellation of Reflective Interference.

Imaging Photoplethysmography (IPPG) is an emerging and efficient optical method for non-contact measurement of pulse waves using an image sensor. While the contactless way brings convenience, the inevitable distance between the sensor and the subject results in massive specular reflection interference on the skin surface, which leads to a low Signal to Interference plus Noise Ratio (SINR) of IPPG. To ease this challenge, this work proposes a novel modulation illumination approach to measure the accurate arterial pulse wave via surface reflection interference isolation from IPPG. Based on the proposed skin reflection model, a specific modulation illumination is designed to separate the surface reflections and obtain the subcutaneous diffuse reflections containing the pulse wave information. Compared with the results under ambient illumination and constant supplemental illumination, the SINR of the proposed method is improved by 4.56 and 3.74 dB, respectively.

A feasible way to explore real blood vessels thermal responses to laser irradiation by combing optical clearing and the reflectance spectra measurements: animal experiment study.

Laser therapy has been widely used to treat port-wine stains (PWS) and other cutaneous vascular lesions via selective photothermolysis. Animal models are a valuable tool for investigating thermal responses beneath the skin. However, in previous animal experiments, such as the dorsal skin chamber model, one side of the skin was removed, resulting in the loss of mechanical support for the target blood vessel. In this study, the optical clearing technique was applied to the dorsal skin, allowing direct observation of real thermal responses within the tissue without removing the covering skin. The target blood vessels were irradiated with a pulsed 1064nm Nd: YAG laser. The corresponding thermal responses were recorded using a CCD camera. Additionally, variations in skin reflectance spectra were measured before and after laser irradiation. Due to the optical clearing and reflectance spectra measurement, vessel responses such as contraction, reperfusion, and full occlusion were correlated with specific variation patterns in reflectance spectral signals.

Quantitative skin surface hydration measurement by visible optical image processing: A pilot study.

Skin barrier function is significantly impacted by skin moisture. Most non-invasive evaluation techniques to measure skin surface hydration relying on its electrical properties, which are limited in scope and have unstable operations. Applying image processing for skin hydration assessment is uncommon, with an emphasis on skin-capacitive pictures and near-infrared images in general, which demand a certain spectrum. As a result, there is an increasing need for wide-area skin hydration evaluation and mapping. Thestudy aimsto propose a quantitative evaluation algorithmforskin surface hydrationfrom visible-light images. Threedeviceswere applied tomeasureskin hydration:skin image capturedevice and tworecognizedcommercialskindevices.A digital image processing system creates a new index, called GVR, to symbolize skin surface moisture. TheCLAHE algorithmwas appliedto enhance the contrast of skin image, andafter calculating it with the monochrome image,the skin reflectance imagewas segmented.The GVR was estimated using the values of the individual sites and the entire skin. The correlation coefficient between the three methods was examined using statistical analysis to assess the performance of GVR. Skin hydrationestimated from visible-light imagesis influenced by the entire facial structure in addition to specific areas.The electrical and visible image evaluations showed a strong association with a significant difference. It was discovered that reflecting measures from visible images provide a quick and efficient way to quantify the moisture of the skin's surface.

Seasonal and altitudinal variation in dorsal skin reflectance and thermic rates in a high-altitude montane lizard.

Temperature is one of the most important factors in the life histories of ectotherms, as body temperature has an undeniable effect on growth, activity, and reproduction. Lizards have a wide variety of strategies to acquire and maintain body temperature in an optimal range. The "Thermal Melanism Hypothesis" proposes that individuals with lower skin reflectance can heat up faster as a result of absorbing more solar radiation compared to lighter conspecifics. Therefore, having a darker coloration might be advantageous in cold habitats. Dorsal skin reflectance has been found to change rapidly with body temperature in several lizard species, and it can also vary over longer, seasonal time scales. These variations may be important in thermoregulation, especially in lizards that inhabit areas with a large temperature variation during the year. Here, we study how dorsal reflectance fluctuates with body temperature and varies among seasons. We compared dorsal skin reflectance at three body temperature treatments, and measured thermal rates (i.e., heat and cool rate, thermic lapse, and net heat gain) by elevation (2500-4100m) and seasons (spring, summer, and autumn) in the mesquite lizard, Sceloporus grammicus. Our results show that lizards were darker at high elevations and during the months with the lowest environmental temperatures. The rate of obtaining and retaining heat also varied during the year and was highest during the reproductive season. Our results indicate that the variation of dorsal skin reflectance and thermal rates follows a complex pattern in lizard populations and is affected by both elevation and season.

Short-term skin carotenoid changes following consumption of a typical Australian diet versus a healthy Australian diet: findings from a randomised crossover feeding trial

Carotenoids, a group of phytochemicals found in plant-based foods with yellow, red, or orange pigments, have been shown to be stored in the skin upon consumption of carotenoid-rich foods(1). Skin carotenoid levels can be measured using skin reflectance spectroscopy, which assesses skin lightness (L*), redness (a*), and yellowness (b*)(2). Previous research has demonstrated significant increases in skin yellowness (b*) after a 4-week high-carotenoid diet(2). The aim was to examine shorter-term changes (two weeks) in skin yellowness following the consumption of a Healthy Australian Diet rich in carotenoids compared to a Typical Australian Diet with low carotenoid content. The study analysed data from an eight-week randomised, cross-over feeding trial involving 34 adults (53% female, aged 38.44 ± 18.05 years). Participants were randomly assigned to each diet for two weeks, separated by a two-week washout period. The Healthy Australian Diet adhered to the Australian Dietary Guidelines(3), emphasising the consumption of carotenoid-rich fruits and vegetables such as carrots, pumpkin, tomatoes, red capsicum, and sweet potatoes. In contrast, the Typical Australian Diet was formulated based on apparent consumption patterns in Australia(4) and emphasised the intake of fruits and vegetables low in beta-carotene, such as white potatoes, onions, cauliflower, and pears. Skin carotenoids were measured using skin reflectance spectroscopy at three sites (palm, inner and outer arm), and each measurement was taken thrice. Overall skin yellowness (b*) was calculated as the average of all three measurements at all three sites. Measurements were conducted at four key visits: week 0 (end of run-in; baseline 1), week 2 (post-feeding phase 1), week 4 (end of washout; baseline 2), and week 8 (post-feeding phase 2). Differential changes in skin carotenoid levels between intervention groups were assessed using linear mixed-effect models, adjusting for diet sequence, feeding phase, body fat percentage, total fat intake, and subject ID as a random variable to account for potential autocorrelation. Post-hoc pairwise comparisons were conducted to evaluate the relative effects of each diet. Although there was a trend towards higher skin yellowness (0.215 ± 0.517; p = 0.41) following consumption of the Healthy Australian diet relative to baseline, and an inverse trend following the Typical Australian Diet (−0.118 ± 0.539, p = 0.56), the difference in change between the two diets was not statistically significant (p = 0.32). Notably, baseline values within this participant cohort were higher than previously reported at b* = 16.7(1) (baseline 1 b*: 17.57 ± 2.23, baseline 2 b*: 17.71 ± 2.26), which may influence the magnitude of observable change. The findings suggest that the two-week intervention duration may be insufficient to achieve statistically significant changes in skin carotenoid levels. Future investigations into whether plasma carotenoids increase first, with skin changes occurring later, could offer valuable insights into the potential utility of this as a biomarker validation of change in fruit and vegetable intake.

A robust non-contact heart rate estimation from facial video based on a non-parametric signal extraction model

Remote photoplethysmography (rPPG) is a non-contact method to extract heart rate (HR) pulse signals from facial videos. However, challenges persist due to head motion disturbances and ambient illumination variations. To address these issues, a novel non-parametric signal extraction model is proposed for HR estimation using the webcam camera. We first select the better-quality RGB signal from the divided face regions through the ranking of signal-to-noise ratio (SNR). Then, we use blind source separation and skin reflection modeling to eliminate the effect of ambient illumination. Finally, we employ a non-parametric signal extraction model named circulant singular spectrum analysis (CiSSA), with frequency-based decomposition and energy-driven reconstruction, to extract the HR-related pulse signal effectively. To evaluate the performance of our method, we conducted the validation experiments on three datasets, including two public datasets (UBFC and PURE dataset) and one self-collected dataset (ILVA dataset). Our method outperformed significantly on all three datasets, achieving Mean Absolute Deviation (MAD) of 2.42, 1.36, and 2.84 bpm, Root Mean Square Error (RMSE) of 1.89, 2.24, and 3.58 bpm, and Pearson Correlation Coefficients (PCC) of 0.98, 0.98, and 0.93, respectively. The experimental results demonstrate that our method achieves comparable performance, particularly in scenarios involving severe head motion disturbances and variations in ambient illumination.

Dynamic model for the strain-modulated spectral reflectance of the human skin in vivo.

Hyperspectral imaging (HSI) offers a wealth of information regarding human skin. In this study, we established a dynamic skin spectral reflectance model (DSSR) relating the reflectance to skin surface strain, considering multi physiological and physical parameters of the skin. Experimentally, by HSI, we measured the reflectance variance of the forearm skin in vivo caused by the surface strain, and assessed these key parameters. For the human skin in vivo, within the strain range covered in this paper, stretching increases spectral reflectance, while compression decreases it. Our proposed model provides a possibility for non-contact strain measurement and health monitoring on the skin in vivo based on HSI.

Analysis of Skin Color Variation using CIELAB Index: An Empirical Study from Delhi, India

Skin color is a conspicuous trait regulated by complex metabolic processes and its significant diversity among Indian populations is quite remarkable making it an ideal choice for dermatological investigation. To elucidate skin pigment variation with respect to age, we studied 714 healthy individuals (aged 20-70 years) using CIELAB system. Skin reflectance was measured from the volar surface of upper arm using DSM II ColorMeter (Cortex Technology, Hadsund, Denmark) among population of Delhi, India to provide CIELAB color space values, L* (light/dark), a* (red/green), and b* (yellow/blue) followed by statistical analysis to examine the correlation between age and gender on skin on constitutive skin pigmentation. The studied parameters were observed to vary widely {L* (Range: 24.98-51.62, M=38.66, SD=4.41), a* (Range: 4.61-17.16, M=10.18, SD=2.03), and b* (Range: 20.16-34.83, M=28.93, SD=2.30)} across all age groups. ANOVA results suggest a statistically significant effect of age on skin lightness {F(4,709)=124.1332, p&lt;0.001}, redness {F(4,709)=20.0594, p&lt;0.001} and yellowness {F(4,709)=95.1434, p&lt;0.001}. Positive correlation was observed between age and both hue (ho) {r(712)=0.9027, p&lt;0.001} and chroma (C) {r(712)=0.9224, p&lt;0.001}. Significant effects of gender were noticed on skin lightness among all age groups, along with skin redness below the age of 40 years (p&lt;0.001). Notable color differences (∆Ε∗ab) were witnessed among males and females across all age groups in the studied population. The age group 21-30 years was found to have the highest ∆Ε∗ab value (3.5987), followed by 51-60 years (2.98), 31-40 years (2.5579), 61-70 years (2.1837), and 41-50 years (1.6639). We would like to highlight that skin lightness, redness, and yellowness differs significantly with age. Females were observed to be lighter in color as compared to males across all age groups. The findings of the current study would provide better understanding of skin color variation among Indian population.

Homogenous and multilayer electromagnetics models for estimating skin reflectance

&lt;span&gt;Reflectance measurements of human skin are widely limited over the millimeter wave (MMW) band in literature. This is due to the cost and technical difficulties of the experimental setup. This paper proposes homogenous and multilayer skin models for estimating the reflectance of the forearm and palm of the hand skin over the MMW band 30-100 GHz. The simulation results demonstrate that the differences in reflectance between the homogenous and multilayer models of forearm skin are limited to 0.014, indicating that the thin stratum corneum (SC) layer in the multilayer skin models has a minimal impact on the interaction with MMW of the forearm skin. However, in the palm of hand skin, there is a substantial difference in reflectance calculations between the homogenous and the multilayer skin models in the range of 0.099 to 0.143. These differences are attributed to the presence of a thick SC layer in the palm of the hand. Thus, the simulation results suggested that two-layer should be used for the palm of hand skin as it better captures the reflectance characteristics of this region. The importance of having those models are in calculating the skin reflectance that can be used for the non-invasive diagnosis of skin conditions.&lt;/span&gt;

Assessment of Skin Maturity by LED Light at Birth and Its Association With Lung Maturity: Clinical Trial Secondary Outcomes

Background Clinicians face barriers when assessing lung maturity at birth due to global inequalities. Still, strategies for testing based solely on gestational age to predict the likelihood of respiratory distress syndrome (RDS) do not offer a comprehensive approach to addressing the challenge of uncertain outcomes. We hypothesize that a noninvasive assessment of skin maturity may indicate lung maturity. Objective This study aimed to assess the association between a newborn’s skin maturity and RDS occurrence. Methods We conducted a case-control nested in a prospective cohort study, a secondary endpoint of a multicenter clinical trial. The study was carried out in 5 Brazilian urban reference centers for highly complex perinatal care. Of 781 newborns from the cohort study, 640 were selected for the case-control analysis. Newborns with RDS formed the case group and newborns without RDS were the controls. All newborns with other diseases exhibiting respiratory manifestations were excluded. Skin maturity was assessed from the newborn's skin over the sole by an optical device that acquired a reflection signal through an LED sensor. The device, previously validated, measured and recorded skin reflectance. Clinical data related to respiratory outcomes were gathered from medical records during the 72-hour follow-up of the newborn, or until discharge or death, whichever occurred first. The main outcome measure was the association between skin reflectance and RDS using univariate and multivariate binary logistic regression. Additionally, we assessed the connection between skin reflectance and factors such as neonatal intensive care unit (NICU) admission and the need for ventilatory support. Results Out of 604 newborns, 470 (73.4%) were from the RDS group and 170 (26.6%) were from the control group. According to comparisons between the groups, newborns with RDS had a younger gestational age (31.6 vs 39.1 weeks, P&lt;.001) and birth weight (1491 vs 3121 grams, P&lt;.001) than controls. Skin reflectance was associated with RDS (odds ratio [OR] 0.982, 95% CI 0.979-0.985, R2=0.632, P&lt;.001). This relationship remained significant when adjusted by the cofactors antenatal corticosteroid and birth weight (OR 0.994, 95% CI 0.990-0.998, R2=0.843, P&lt;.001). Secondary outcomes also showed differences in skin reflectance. The mean difference was 0.219 (95% CI 0.200-0.238) between newborns that required ventilatory support versus those that did not and 0.223 (95% CI 0.205-0.241) between newborns that required NICU admission versus those that did not. Skin reflectance was associated with ventilatory support (OR 0.996, 95% CI 0.992-0.999, R2=0.814, P=.01) and with NICU admission (OR 0.994, 95% CI 0.990-0.998, R2=0.867, P=.004). Conclusions Our findings present a potential marker of lung immaturity at birth using the indirect method of skin assessment. Using the RDS clinical condition and a medical device, this study demonstrated the synchrony between lung and skin maturity. Trial Registration Registro Brasileiro de Ensaios Clínicos (ReBEC) RBR-3f5bm5; https://tinyurl.com/9fb7zrdb International Registered Report Identifier (IRRID) RR2-10.1136/bmjopen-2018-027442

Effects of skin tone on photoacoustic imaging and oximetry.

Photoacoustic imaging (PAI) provides contrast based on the concentration of optical absorbers in tissue, enabling the assessment of functional physiological parameters such as blood oxygen saturation (). Recent evidence suggests that variation in melanin levels in the epidermis leads to measurement biases in optical technologies, which could potentially limit the application of these biomarkers in diverse populations. To examine the effects of skin melanin pigmentation on PAI and oximetry. We evaluated the effects of skin tone in PAI using a computational skin model, two-layer melanin-containing tissue-mimicking phantoms, and mice of a consistent genetic background with varying pigmentations. The computational skin model was validated by simulating the diffuse reflectance spectrum using the adding-doubling method, allowing us to assign our simulation parameters to approximate Fitzpatrick skin types. Monte Carlo simulations and acoustic simulations were run to obtain idealized photoacoustic images of our skin model. Photoacoustic images of the phantoms and mice were acquired using a commercial instrument. Reconstructed images were processed with linear spectral unmixing to estimate blood oxygenation. Linear unmixing results were compared with a learned unmixing approach based on gradient-boosted regression. Our computational skin model was consistent with representative literature for in vivo skin reflectance measurements. We observed consistent spectral coloring effects across all model systems, with an overestimation of and more image artifacts observed with increasing melanin concentration. The learned unmixing approach reduced the measurement bias, but predictions made at lower blood still suffered from a skin tone-dependent effect. PAI demonstrates measurement bias, including an overestimation of blood , in higher Fitzpatrick skin types. Future research should aim to characterize this effect in humans to ensure equitable application of the technology.

Can Bergmann’s Rule and the Thermal Melanism Hypothesis explain the variation in colour and size observed in the wild bee Eoanthidium insulare (Apoidea: Megachilidae) across its Palaearctic range?

To analyse geographic variation patterns and assess the applicability of biogeographical rules in insects, the West Palaearctic anthidiine bee Eoanthidium insulare serves as an excellent model. This species showcases a highly variable black-and-yellow colour pattern, with a distribution spanning over 4400 km from the Adriatic Sea to the Pamir Mountains and extending over 1660 km in a south-north direction. We examined 214 specimens from all geographic regions of its distribution and identified a significant increase in both body size and the proportion of black in the integument from south to north. This phenomenon may be attributed to a more efficient exploitation of solar energy through a larger integument surface area (Bergmann’s Rule) and enhanced heat retention due to lower skin reflectance (Thermal Melanism Hypothesis). These two processes, therefore, complement each other. However, despite the cooler climates at higher altitudes, we found no correlations between body size and altitude. Furthermore, while we observed an increase in the proportion of black in the integument from east to west, there was no significant increase in body size. Notably, no correlation between body size and body colouration was identified, suggesting that size and colour adaptation are independent processes. Given that the various colour and size patterns were identified as clinal rather than discontinuous, and the intraspecific genetic distance across the distribution area was remarkably low (0.00138), featuring only four distinct haplotypes of the mitochondrial COI region DNA sequence, we suggest that the subspecies E. i. persicolum and E. i. lemesium be regarded as synonymous with the nominate subspecies (syn. nov.). These findings suggest that, although Bergmann’s Rule and the Thermal Melanism Hypothesis can account for certain aspects of geographic variation in the body size and colouration of E. insulare, their effects may be influenced or superimposed by factors such as genetic constitution.

Low-Cost 3-D Millimeter-Wave Concealed Weapons Detection Using Single Transceiver Affine Synthetic Arrays

The problem of detecting concealed weapons with a low-cost 3-D imaging radar system is addressed. The concept of affine phase center translations to generate a synthetic array is proposed as an alternative to conventional synthetic aperture and multistatic imaging radars. This enables the generation of a synthetic 2-D array with a dynamic dual reflector antenna system and a single transceiver. The dual reflector antenna is composed of a 3-D printed ellipsoidal sub-reflector and a conic main reflector. The phase front of the horn feed is shown to be translated to different locations by controlling the relative positions of the two reflectors. The reflectors are fabricated using a simple protocol that keeps the cost very low but introduces significant phase aberrations. These phase aberrations are corrected by developing a novel geometrical optics based optimized calibration routine. The imaging system is tested using a 76.5–84.5 GHz stepped frequency transceiver in different concealed weapons detection scenarios. As a demonstration, a metallic handgun and a nonmetallic pipe-bomb are concealed on a mannequin which serves as a human surrogate with similar skin reflectivity. At a target distance of 2.8 m the achieved depth resolution and lateral resolution are 2 and 1.5 cm, respectively. The 3-D images constructed using back-projection are of high enough quality to successfully identify the weapons while maintaining the privacy of the individual.

Characterization and Efficacy of Essential Oil-Based Cosmetic Formulations for Acne-Prone Skin

This randomized, placebo-controlled, double-blind clinical in vivo study aimed to evaluate the clinical efficacy of a cosmetic formulation for non-inflammatory acne using essential oils. Fifty-three male participants were divided into four groups: a formulation containing a mixture of four essential oils (4EO), Melaleuca alternifolia (M.a.), nanoemulsion of M. alternifolia (Nanoem.), and a placebo group. The participants applied the formulation daily for 90 days and non-invasive skin imaging techniques were employed to assess the outcomes. Skin microrelief images and reflectance confocal microscopy images were captured in the malar region, and Raman spectroscopy was used to analyze the terpene composition of the essential oils, oil mixture, and nanoemulsion. The results indicated that the nanoemulsion, M.a. essential oil, and 4EO formulation effectively reduced the overall number of comedone and improved follicular hyperkeratinization. The nanoemulsion of M.a. demonstrated the most promising outcomes in reducing comedone areas, especially in the infundibular region. This effect could be attributed to the presence of terpinene-4-ol in the essential oil and the enhanced penetration provided by the nanoemulsion formulation. These findings suggest that cosmetic formulations containing essential oils, particularly in nanoemulsion form, have potential against mild acne. This study contributes to our understanding of the relationship between terpene composition and clinical activity, highlighting the importance of innovative delivery systems.

Respiratory distress syndrome prediction at birth by optical skin maturity assessment and machine learning models for limited-resource settings: a development and validation study.

A handheld optical device was developed to evaluate a newborn's skin maturity by assessing the photobiological properties of the tissue and processing it with other variables to predict early neonatal prognosis related to prematurity. This study assessed the device's ability to predict respiratory distress syndrome (RDS). To assess the device's utility we enrolled newborns at childbirth in six urban perinatal centers from two multicenter single-blinded clinical trials. All newborns had inpatient follow-up until 72 h of life. We trained supervised machine learning models with data from 780 newborns in a Brazilian trial and provided external validation with data from 305 low-birth-weight newborns from another trial that assessed Brazilian and Mozambican newborns. The index test measured skin optical reflection with an optical sensor and adjusted acquired values with clinical variables such as birth weight and prenatal corticoid exposition for lung maturity, maternal diabetes, and hypertensive disturbances. The performance of the models was evaluated using intrasample k-parts cross-validation and external validation in an independent sample. Models adjusting three predictors (skin reflection, birth weight, and antenatal corticoid exposure) or five predictors had a similar performance, including or not maternal diabetes and hypertensive diseases. The best global accuracy was 89.7 (95% CI: 87.4 to 91.8, with a high sensitivity of 85.6% (80.2 to 90.0) and specificity of 91.3% (95% CI: 88.7 to 93.5). The test correctly discriminated RDS newborns in external validation, with 82.3% (95% CI: 77.5 to 86.4) accuracy. Our findings demonstrate a new way to assess a newborn's lung maturity, providing potential opportunities for earlier and more effective care. RBR-3f5bm5 (online access: http://www.ensaiosclinicos.gov.br/rg/RBR-3f5bm5/), and RBR-33mjf (online access: https://ensaiosclinicos.gov.br/rg/RBR-33rnjf/).

Detail-preserving arterial pulse wave measurement based Biorthogonal wavelet decomposition from remote RGB observations

Extracting arterial pulse wave from the video, also known as Imaging Photoplethysmography (IPPG), has emerged as an efficient health monitoring approach. The detail-preserving arterial pulse wave can significantly improve healthcare efficiency through the provision of physiological and pathological information. However, the accurate measurement of arterial pulse wave by IPPG is still challenged by the fact that the pulsation is weakly expressed at the skin surface and extremely vulnerable to interferences. This work proposes a novel approach to measure the detail-preserving arterial pulse wave via interference isolation from facial video. A skin reflection model is introduced to guide the design of the IPPG measurement system, where the IPPG signal is pre-filtered to obtain the variation related to the pulse wave, and a Biorthogonal wavelet is further employed to distinguish the unique pattern of arterial subtle variation from interferences. Experimental results validate the efficiency of proposed method with a correlation coefficient of 0.92.

The Use of Hemispheric Directional Reflectance Method to Verify the Usefulness of Filters Protecting the Skin Against Infrared Radiation.

Infrared radiation (IR) has a wide spectrum of both positive and harmful effects on the human body. Negative properties, manifested by increasing the level of reactive oxygen species (ROS), affect the skin ageing acceleration. Other adverse effect of infrared exposure is related to its ability to significantly penetrate deep into the skin, between its layers, up to blood vessels and other tissues and warm them up. Due to its harmful effects, protecting the skin against infrared radiation becomes an important issue. The aim of the research was verifying the usefulness of filters available on the market with protection against infrared radiation declared by the manufacturers, by examining their impact on the directional reflectance of the human skin. A group of 27 people was gathered, to obtain the results. Four products were applied on the participant's forearm skin, and then measurements of the directional reflectance of the skin were made at successive time points, using the 410-Solar reflectometer. The collected data was analyzed, and showed changes in reflectance under the influence of the applied protective products. The products used in the study showed a statistically significant effect on the directional reflectance of the human skin in near infrared radiation range and little effectiveness for higher wavelengths. The results indicate that the selected products show radiation protection against IR radiation only after several dozen minutes of application, which may suggest that they must penetrate deeper skin layers to be effective. Hemispheric directional reflectance turned out to be an effective method allows to assess the effectiveness of protective properties of cosmetics.

Effect of Narrow-Band Ultraviolet B Therapy of Psoriasis Vulgaris on Skin Directional Reflectance, Skin Density and Epidermal Thickness

Psoriasis is an inflammatory dermatosis manifested by the appearance of brown-red papules on the body, covered with silver scales. One of the most common and effective treatments for psoriasis is narrow-band UVB phototherapy. Narrow-band UVB has a wavelength of 311 nm, which results in shallow skin penetration, is absorbed only by the epidermis and the superficial layers of the dermis. The aim of the study was to assess the effect of narrow-band UVB 311 nm phototherapy on skin covered with psoriatic scales and without psoriatic lesions in patients with psoriasis vulgaris on the total directional hemispherical reflectance (DHR) of the skin, skin density and epidermis thickness. For this purpose, a 410 Solar DHR reflectometer and high-frequency ultrasonography DUB SkinScanner were used. A total of 48 volunteers were enrolled. There was a difference in the reflectance of skin without psoriatic scales and psoriatic skin. Depending on the wavelength range, the skin was characterized by different reflectance values. During the course of phototherapy, the reflectance values decreased, both in the psoriatic skin and skin without psoriatic scales. After the phototherapy, the epidermis thickness and SLEB layer decreased and skin density increased in the area with psoriatic plaque. The density of the skin without psoriasis after a series of 20 irradiations increased, while the thickness of the epidermis did not change.

Living-skin Detection using Multi-layer Skin Property Perceived by the Structured Light.

Living-skin detection has been used to prevent the attack of face fraud in a face recognition system. In this paper, we propose a new concept that exploits the multi-layer structure property of skin for living-skin detection. We observe a significant difference in the blur of the laser spot created by the structured light on the skin and non-skin due to the characteristic properties of laser photons in skin penetration and reflection. Based on this observation, we designed a new living-skin detection algorithm to differentiate skin and non-skin based on the blur detection of laser spots. The experimental results show that the proposed setup and method have a promising performance with an averaged precision of 96.7%, averaged recall of 82.2%, and averaged F1-score of 88.6% on a dataset of 20 adult subjects. This demonstrates the effectiveness of the new concept that uses multi-layer properties of skin tissues for living-skin detection, which may lead to new solutions for face anti-spoofing.