Digital camera images obtained using a light-emitting diode illuminator and their dermatological applications

BACKGROUND/PURPOSE: Although digital cameras have powerful macrocapabilities, flash macrophotographs are often unsatisfactory. The aim of this study was to develop a light-emitting diode (LED) illuminator for macro digital photography that allows colorimetric investigations of the skin. METHODS: We devised an LED illuminator suitable for acquiring super-macro digital images of the skin. Reference CIELAB color chart values were compared statistically with computed values from digital images in order to obtain equations for real CIELAB values. Using these, we acquired and analyzed images of various dermatological conditions using an LED illuminator. RESULTS: The images obtained with the devised LED illuminator were more reproducible than flash-assisted photographs. With proper camera settings, the devised LED illuminator and the color analysis method developed during this study provided digital skin images containing colorimetric information. CONCLUSION: A digital camera equipped with an LED illuminator is a useful tool for dermatological research and clinical practice.     

A novel ultraviolet photography technique for assessing photodamage

Photography is critical to accurately capturing clinical results in cosmetic dermatology.  However, this shift from film to digital photography has made the capture of true ultraviolet (UV) images more difficult. Film cameras were developed that used special lighting and film to create true UV images, but this technology has not translated into the digital realm. At present, commercial digital photography systems use computer processing to generate UV-like images from visible light photography. This research developed a technique to obtain UV images with a UV pass glass filter placed in front of the camera lens. The UV filter was opaque to visible light (400–750 nm) with a peak transmission at 360 nm. In addition, a glass infrared (IR) block filter was also placed in front of the UV filter during photography. This research resulted in the development of an affordable digital camera system that was able to capture true UV light photographs.  This technique can be used by research and clinical dermatologists to obtain photographs demonstrating changes in photodamage as a result of therapeutic intervention.     

A quantitative assessment of the human skin surface using polarized light digital photography and its dermatologic significance

Background: Quantitative and objective investigations of parallel‐polarized light (PPL) photography for dermatologic purposes are scarce. Objective: To determine the significance of quantitative analysis of PPL photography to develop objective measurement methods of skin surface characteristics. Method: For PPL photography, a digital camera, a light‐emitting diode illuminator, and polarizing filters were arranged and kept constant. We analyzed the PPL photography images of the glabella, the medial aspect of the forearm, and the posterior aspect of the lower leg, and measured the CIELAB values. A dermatologist evaluated the clinical severity of the actual photographed sites with respect to glossiness and dryness. These clinical severities were compared statistically with the CIELAB values. Results: According to the correlation analysis, the L^* value was negatively correlated with dryness (r=?0.29869, P=0.0047) and glossiness (r=?0.35367, P=0.0185). Conclusion: The method used in this study is applicable to the quantitative evaluations of other dermatologic diseases or conditions, especially in relation to skin surface changes.     

Objective evaluation of skin prick test reactions using digital photography

BACKGROUND: The skin prick test has been used worldwide to determine IgE-mediated hypersensitivity. However, the most current method to record this reaction has problems with accuracy and precision. OBJECTIVE: To demonstrate a new approach to measure the skin prick reaction and its kinetics with precision. METHODS: The skin prick test was induced using histamine or Dermatophagoides pteronyssinus antigen in 80 volunteers aged 4 and 67 years who had different skin colors. Digital photographs were obtained at 0, 3, 5, 10, 15 and 20 min. The mean wheal and erythema area as well as the erythema intensity were determined using Adobe Photoshop software. The accuracy and precision of this approach were also evaluated. RESULTS: The digital photographic analysis measured the wheal and erythema sizes independent of the antigen or skin color with precision. In addition, a new variable of this test, the skin erythema intensity, could be determined objectively using the chromaticity of reflected light. CONCLUSIONS: Digital photographic analysis is a precise and objective method to evaluate the skin prick test reaction, which can be used independent of the patient's skin color in clinical or research settings.     

Practical color calibration for dermoscopy, applied to a digital epiluminescence microscope

BACKGROUND/PURPOSE: The assessment of colors is essential for melanoma (MM) diagnosis, both for pattern analysis on dermoscopic images, and when using semiquantitative methods. Our aim was to provide a simple, precise characterization and reproducible calibration of the color response for dermoscopic instruments. METHODS: Three processes were used to correct the non-uniform illumination pattern of the instrument, to easily estimate the camera gamma settings and to describe the color space conversion matrices required to produce standard images, in any color space. A specific color space was also developed to optimize the representation of dermatoscopic colors. The calibration technique was tested both on synthetic reference surfaces and on real images by comparing the difference between the images colors obtained with two different equipments. RESULTS: The differences between the images acquired by means of the two instruments, calculated on the reference patterns after calibration, were up to 10 times lower then before, while comparison of histograms referring to real images provided an improvement of about seven times on average. CONCLUSIONS: A complete workflow for dermatologic image calibration, which allows the user to continue using his own software and algorithms, but with a much higher informative content, is presented. The technique is simple and may improve cooperation between different research centers, in teleconsulting contexts or for result comparisons.     

A device for the color measurement and detection of spots on the skin

Background/purpose: In this work, we present a new and fast easy-to-use device that allows the measurement of color and the detection of spots on the human skin. The developed device is highly practical for relatively untrained operators and uses inexpensive consumer equipment, such as a CCD color camera, a light source composed of LEDs and a laptop. The knowledge of the color of the skin and the detection of spots can be useful in several areas such as in dermatology applications, the cosmetics industry, the biometrics field, health care, etc.
Methods: In order to perform these measurements the system takes a picture of the skin. After that, the operator selects the region of the skin to be analyzed on the displayed image and the system provides the CIELAB color coordinates, the chroma and the ITA parameter (Individual Tipology Angle), allowing the comparison with other reference images by means of CIELAB color differences. The system also detects spots, such as freckles, age spots, sunspots, pimples, black heads, etc., in a determined region, allowing the objective measurement of their size and area.
Results: The colorimetric information provided by a conventional spectrophotometer for the tested samples and the computed values obtained with the new developed system are quite similar, meaning that the developed system can be used to perform color measurements with relatively high accuracy. On the other hand, the feasibility of the system in order to detect and measure spots on the human skin has also been checked over a great amount of images, obtaining results with high precision.
Conclusion: In this work, we present a new system that may be very useful in order to measure the color and to detect spots of the skin. Its portability and easy applicability will be very useful in dermatologic and cosmetic studies.     

The development of a filter to enhance the efficacy and safety of excimer light (308 nm) therapy

Background: Excimer light (308 nm) therapy is a new ultraviolet (UV) B phototherapy for which the efficacy and resulting DNA damage are not well established.
Purpose: To develop an effective and safe phototherapy using the excimer lamp, we studied the effects of different light cut-off filters, A and B.
Methods: Efficacy was evaluated by measuring apoptosis using fluorescence-activated cell sorting analysis. DNA damage was evaluated by measuring cyclobutane pyrimidine dimers (CPDs). Light sources, including normal wave and short wave (SW) excimer light, broad-band (BB) UVB, and narrow-band (NB) UVB, were examined using the filters. A human skin equivalent model was also examined.
Results: The ratio of positive apoptosis to CPD formation normalized to the mean induced by NB-UVB was 5.7 using the excimer lamp without a filter, 6.3 using the excimer lamp with the A filter, 6.4 using the SW excimer lamp without a filter, and 4.2 using the BB-UVB. The A filter reduced CPD formation induced by the normal wave and SW excimer lamp. In the human skin equivalent model, the use of filters significantly decreased the amount of CPD-positive cells.
Conclusions: These findings suggest that using the A filter with the excimer lamp increases the efficacy and safety of excimer light therapy.     

Blue in the skin

BACKGROUND: The most prevalent theory explaining blue colors in skin is that of bluish scatter. If this accounted for blue perception, it would be measurable since a predominance of scattered blue light should emerge as a measurable reflectance. When objects are viewed with chromatic surround, there may be an increased perception of the hue complementary to their background. This effect, known as color contrast, is a well-established phenomenon and depends on the size, lightness, and intensity of the surrounding color. OBJECTIVE: The purpose of this article is to determine the effect of background on the perception of blue color from a superficial vein. METHODS: Fifteen subjects were asked to observe the color of skin overlying a vein on the hand. This was performed with a variety of achromatic backgrounds and with variable amounts of surrounding normal skin. Color was also measured by direct matching with standardized Munsell chips and then estimated with normal skin surround. RESULTS: Color matching revealed the hue of the vein to be yellowish-gray, and not blue or green. Although few subjects observed green or blue with neutral backgrounds, as the vein was viewed with progressively larger areas of normal surrounding skin, there was an increasing perception of these colors. CONCLUSION: The bluish color of superficial veins is more clearly explained by color contrast than by scattering. Contrast may also account for the color of certain blue nevi and may help explain some purplish colors in the skin.     

Digital image analysis of facial erythema over time in persons with varied skin pigmentation

Background/purpose: Selected chemotherapeutic agents used for the treatment of cancer are known to cause skin toxicities. One group of agents, epidermal growth factor receptor (EGFR) inhibitors, characteristically precipitates an acneform rash. Currently, no standard of care exists for the management of the rash resulting from EGFR inhibitors. In order to objectively evaluate any management strategy, a method to quantify the rash is required. The purpose of this paper is to describe a method to quantify the erythema of a facial rash through the use of digital photography and image analysis. Methods: A Canfield OMNIA System using a Canon PowerShot Pro1 camera was used to obtain high‐resolution digital images of facial rashes. Digital images were recorded in Joint Photographic Experts Group format, corrected for brightness and white balance and color. A method was developed to analyze digital images of erythema independent of the range of skin pigmentation. Results: Two examples are given to illustrate the method developed and its utility. Conclusion: An inexpensive and portable method is described for objectively monitoring the development of facial erythema in subjects of the full range of skin pigmentation. This method can be used clinically to examine the development and resolution of facial rash erythema in response to treatment.     

Topographic measurement of skin color by narrow-band reflectance spectrophotometer and minimal erythema dose (MED) in Koreans

Background/aims: Narrow-band reflectance spectrophotometer is one of the objective and quantitative devices for measuring the skin colors. There has been some controversy concerning the relationship between the objectively measured skin color and cutaneous responsiveness to ultraviolet radiation, including minimal erythema dose (MED). The aims of this study were to compare the color of Korean brown skin with that of Caucasians by objective measurement with the narrow-band reflectance spectrophotometer, and to determine whether the skin color has any correlation with MED in Koreans, and demonstrate differences in this correlation according to the anatomical sites. Methods: With narrow-band reflectance spectrometer, skin colors were measured at 17 body sites of 20 healthy Korean male volunteers after measuring MED for the same subjects. Results: The constitutional skin color, as measured by the melanin index of the nonexposed sites, showed a statistically significant correlation with MED values, whereas the facultative skin color did not. The Korean brown skin showed higher melanin index and lower erythema index compared with that of Caucasians. Conclusions: We confirmed significant differences in the correlation between MED and melanin indices, depending on the anatomic sites. This suggests that selection from various sites, even among the nonexposed sites, is quite important and deserves further evaluation.     

Digital imaging in clinical dermatology across the UK in the year 2001

Colour photography is an important tool in the daily practice of dermatologists. Digital photography promises quicker acquisition and handling of clinical images. Despite increasing availability and falling costs, dermatologists have been slow in adopting this new technique. To establish to what degree digital photography has found its way into routine practice in dermatology departments in the UK during the year 2001, we conducted a postal survey of all dermatology departments in the UK about usage of digital cameras. A total of 65.4% of the questionnaires were returned. The responses indicated that 71% of departments in teaching hospitals vs. 56% of departments in district general hospitals (DGH) had access to a digital camera. Reasons for not having a digital camera were satisfaction with conventional photography and lack of resources. In 48% of the departments of teaching hospitals or DGH with access to a digital camera, less than 10% of all photos were taken digitally. However, 24% of departments in DGH and 22% in teaching hospitals took more than 80% of their clinical photos digitally, indicating that in many departments digital photography is still in an early phase and only occasionally used, whilst in others a change from conventional photography towards digital photography as the mainly used technique has already taken place. Overall, the main drawbacks of digital photography were poorer resolution in comparison with conventional photography, problems with storage and filing images and time required for downloading and storing images.     

Relationship between constitutive skin color and ultraviolet light sensitivity in Koreans

The assessment of skin sensitivity to ultraviolet (UV) radiation is important in treating a variety of skin diseases and preventing the deleterious effects of UV. Although there are many ways to predict the sensitivity to UVR, controversies exist over their objectivity, correlation, and applicability in various races. For the purpose of evaluating the relationship of skin color and UV responsiveness, this study was performed to assess the validity of constitutive skin color for an individual's UV sensitivity in 80 healthy Korean volunteers. The subjects were divided into two groups: a young-aged group with 40 subjects aged 20-39 years and an old-aged group with 40 subjects aged 43-63 years. A minimal erythema dose (MED) of UVB and minimal immediate pigment darkening dose (MIPDD) of UVA were assessed using a fluorescent lamp (Panasol II, National Biologic Co., Twinberg, USA) and a metal-halide lamp (Dermalight 2001, Mutzhas, Munich, Germany), respectively. The constitutive skin color of buttock was measured with a Minolta Chroma Meter CR-300 (Osaka, Japan), using the CIE (Commission International de l'Eclairege) L*a*b* system. Of the three L*a*b*, we used the L* value to estimate the skin color. For the MED and L* values, the values were inversely proportionate (P<0.05) in the young-aged group; however, no correlation existed in the old-aged group. No relationships existed among Fitzpatrick skin type and MED, skin type and MIPDD. The results of this study indicated that the constitutive skin colors in the young-aged group can be an objective and adequate predictor of cutaneous UV sensitivity.     

The difference between the constitutive and facultative skin color does not reflect skin phototype in Asian skin

BACKGROUND/PURPOSE: The assessment of the sensitivity of human skin to ultraviolet (UV) radiation is important in the area of phototherapy, photodermatoses, photo-aging, photo-carcinogenesis, and photo-protection. Some reports have shown that quantitatively measured skin color is a good indicator for predicting UV sensitivity to human skin in Caucasians. In this study, our aim was to define the correlation between skin color and the skin phototype assessed by the Fitzpatrick method in Asian brown skin. METHODS: A total of 180 medical students with similar life styles were included in this study. Their skin phototype was classified according to the system introduced by Fitzpatrick. Then, using a Minolta Spectrophotometer CM-2002, their skin color was determined on the buttocks and forehead. The buttock color was taken as the constitutive skin color, and the forehead color as the facultative skin color. Using these measured values, we compared the skin color with the skin phototype to find their correlation. Also, we investigated whether the difference between the constitutive and facultative skin colors of each individual had a relationship with his or her skin phototype. RESULTS: The constitutive skin color became darker with increasing skin phototype, and this change was statistically significant. As for the facultative skin color, it also became darker with increasing skin phototype, but was less well correlated with the skin phototype than the constitutive skin color. However, the difference between the constitutive and facultative skin colors did not show consistent results in predicting the skin phototype. CONCLUSION: In this study, we found that the constitutive skin color can be a good indicator of the skin phototype. However, the difference between the constitutive and facultative skin colors of each individual does not give any meaningful information for the assessment of his or her skin phototype in Asian skin.     

Fluorescent image analysis for evaluating the condition of facial sebaceous follicles

Background/purpose: Conventional methods, such as 'Sebutape' and 'Sebumeter,' can provide quantitative information on sebum excretion but cannot reflect the condition of sebaceous follicles that can be indirectly evaluated with fluorescent colors of sebum. The images of sebum excretion can be obtained with an ultraviolet-A light that is generally called 'Wood's Lamp.' In this study, we describe fluorescent image analysis methods for the detection of sebum and the color segmentation of sebum to evaluate the condition of sebaceous follicles.
Methods/results: For subject-dependent automatic image analysis, we extracted calibrated image analysis methods that were optimized for digital fluorescent images acquired from our imaging system. The calibrated subjective threshold values for sebum detection were determined by statistically analyzing the number of sebum detected by the automatic threshold value method and the subjective threshold value method ( R =0.947, the number of volunteers: 29). In fluorescent color analysis of sebum, the calibrated reference color markers for the red and white colors were extracted with a coefficient of variance of <10%.
Conclusion: We are confident that such calibrated image analysis methods in combination with our imaging system can provide useful quantitative diagnostic information for sebum-related skin pathologies.     

利用影像比色计对肤色进行定量分析

目的　探索用影像比色计对肤色进行定量测定的临床意义。方法　用摄像机和图像分析装置组合成非接触性肤色测量装置———影像比色计 ,对肤色进行定量测定和分析。结果　影像比色计较反射式分光光度仪对肤色测量的精确度明显提高 ,并能对所获取的图像进行长期保存和比较分析。色彩指数a 或b 增大表示大红色或大黄色增强。日本人正常肤色的色度角在 50°～ 70°范围之内。结论　该方法科学、易行 ,适用于有关肤色疾病的诊断和治疗效果的评价。影像CIE L表色系各参数对黄色人种肤色的测量和评价具有重要的临床意义     

Consistent cutaneous imaging with commercial digital cameras

OBJECTIVE: To demonstrate how to improve the reproducibility and accuracy of digital images of the skin taken with commercially available digital cameras by transforming them to a standard color space, sRGB. METHODS: Our computer algorithm transforms digital images to the standard sRGB color space. It is based on a card with a number of color squares with known colorimetric properties that is included in the image, thereby removing any ambiguity about the color information in the image. Reproducibility and accuracy of the method were assessed by comparing images of color squares with known colorimetric properties taken with different digital cameras at different exposures and zoom settings. RESULTS: Although calibrated images exhibit markedly improved precision and accuracy compared with noncalibrated images, all variability of the imaging process cannot be eliminated. CONCLUSION: With a little care and effort, a calibrated color chart, and computer software, it is possible to greatly improve the quality of clinical imaging in dermatology and possibly other fields of medicine.     

A basis function feature‐based approach for skin lesion discrimination in dermatology dermoscopy images

Background: Skin lesion color is an important feature for diagnosing malignant melanoma. New basis function correlation features are proposed for discriminating malignant melanoma lesions from benign lesions in dermoscopy images. The proposed features are computed based on correlating the luminance histogram of melanoma or benign labeled relative colors from a specified portion of the skin lesion with a set of basis functions. These features extend previously developed statistical and fuzzy logic‐based relative color histogram analysis techniques for automated mapping of colors representative of melanoma and benign skin lesions from a training set of lesion images. Methods: Using the statistical and fuzzy logic‐based approaches for relative color mapping, melanoma and benign color features are computed over skin lesion region of interest, respectively. Luminance histograms are obtained from the melanoma and benign mapped colors within the lesion region of interest and are correlated with a set of basis functions to quantify the distribution of colors. The histogram analysis techniques and feature calculations are evaluated using a data set of 279 malignant melanomas and 442 benign dysplastic nevi images. Results: Experimental test results showed that combining existing melanoma and benign color features with the proposed basis function features found from the melanoma mapped colors yielded average correct melanoma and benign lesion discrimination rates as high as 86.45% and 83.35%, respectively. Conclusions: The basis function features provide an alternative approach to melanoma discrimination that quantifies the variation and distribution of colors characteristic of melanoma and benign skin lesions.     

Skin color measurement in Chinese female population: analysis of 407 cases from 4 major cities of China

BACKGROUND: Color assessment of human skin is an important index both in dermatology and in cosmetology. METHODS: Skin color measured in 407 Chinese women selected from four different cities in China is reported in the 1976 Commission International de L'eclairage (CIE)-color space, according to the skin color typing method proposed by Chardon et al. in 1991. The skin color of buttocks and hands, which represent sun unexposed and exposed sites, respectively, were measured with a Minolta 2500d chromameter. Individual typology angle (ITA degrees) of each volunteer was calculated based on the measured L* and b* values and her skin complexion was graded accordingly. RESULTS: The results show that most of the volunteers had a "light" skin color at their unexposed sites, namely grade II (65.5%), and then grade III (intermediate, 23.1%), and I (very light, 9.6%). The skin colors at exposed sites of the studied group were mainly grade III (intermediate, 45.7%), followed by grade IV (tan, 42.0%) and II (light, 7.9%). The difference among the investigated cities, the relationship between skin color and ages, and the complexion changes from unexposed site to exposed site were analyzed based on the data from the research. CONCLUSION: The authors believed that the present results might basically represent the complexion conditions of Chinese women.     

Hair removal using a combination of conducted radiofrequency and optical energies--an 18-month follow-up.

OBJECTIVE: Multiple lasers and intense pulsed light sources have been shown to provide long-term hair removal; however, the management of all dark skin phenotypes and light-colored hair remains problematic. The present study examined the long-term photoepilatory effect of a combined intense pulsed light (IPL) (680-980 nm)/radiofrequency (RF) (10-30 J/cm3) light source and its efficiency for the treatment of multiple skin phenotypes and varied hair colors. METHODS: Forty adult patients (skin phenotypes II-V) with varied facial and non-facial hair colors were treated with a combined IPL/RF technology. Four treatments were carried out over a period of 9-12 months at 8-12-week intervals. Light energy ranged from 15 to 26 J/cm2, while RF energy varied from 10 to 20 J/cm3. Hair counts and photographic evaluation of skin sites were obtained at baseline, and months 1, 3 and 5 after the final treatment session. H&E biopsies were examined at 1 week in five randomly selected study cohorts. RESULTS: Maximum hair reduction was observed at 6-8 weeks after each treatment. An average clearance of 75% was observed in all body locations at 18 months. No significant adverse sequelae were reported. Results showed no significant dependence on skin color: lighter and darker skin types responded similarly to treatment. Histologic evaluation revealed thermal damage to hair follicles with vacuolar degeneration. CONCLUSION: The combined IPL (680-980 nm)/RF light source with contact cooling is a safe and effective method of long-term hair reduction in patients of diversified skin types and varied hair colors and is associated with excellent patient safety.