The International Skin Spectra Archive (ISSA): a multicultural human skin phenotype and colour spectra collection

<b>Introduction</b>The International Skin Spectra Archive (ISSA) offers a detailed collection of spectral and colorimetric data for human skin, encompassing 15,256 records from 2,113 subjects. This data spans from 2012 to 2024 and originates from eleven datasets curated by international laboratories across eight countries: the UK, Spain, China, Japan, Pakistan, Thailand, Iraq, and Saudi Arabia. Each dataset follows a standardised measurement protocol to maintain data consistency.In the ISSA dataset, individual records provide extensive details including record number, data origin, subject identification, and skin type—categorised by ethnicity, gender, age, and body location. The dataset also includes detailed information on the measurement instruments used, such as type, specular component inclusion, wavelength range and interval.Alongside spectral data, each sample also contains CIE colorimetric data, including tristimulus values, xy chromaticity coordinates, CIELAB parameters, etc., based on the CIE 1931 standard colorimetric observer and the CIE standard illuminant D65.<b>Data Records</b>The dataset is organised into two primary spreadsheets: a coding scheme and a datasheet. The datasheet arranges data across columns labelled A to BQ:A: Unique record identifierB: Data origin (linked to an origin table in the coding scheme)C: Subject numberD to G: Ethnicity, gender, age group, and body location (each linked to respective reference tables in the coding scheme)H to L: Instrument details including type and spectral measurement specificsN to BD: Spectral data from 360 nm to 780 nmBF to BQ: CIE colorimetric dataThis structured format ensures that users can easily access and interpret data for diverse research applications.<b>Measurement Protocol</b>The nationality or ethnicity, gender, age, and body location of the subject are important and depend on the requirements of the specific study that needs the measurement of human skin colour. Thus, this information for each participant was first determined through self-evaluation via a questionnaire. In regions with homogeneous populations (e.g., China, Thailand, Japan), all participants belonged to the same ethnic group. In regions with mixed populations (e.g., the UK), participants were provided with a questionnaire that included options for existing ethnicities, mixed ethnicity, and “other” (self-defined). This information was recorded using consistent coding schemes in the dataset.To ensure the integrity and consistency of all skin spectral reflectance measurements in this study, several standardised conditions were rigorously maintained. First, it was essential for the skin of all subjects to be clean, unabraded, and free from any cosmetics, lotions, or medical products that could affect the measurement outcomes. Each subject was prepared accordingly prior to data collection to meet this standard. Additionally, the measurement instruments (portable spectrophotometer - SP) were calibrated according to manufacturer guidelines before each session. Lighting conditions for measurements were carefully controlled; all measurements were conducted under diffuse lighting conditions to avoid discrepancies associated with collimated light sources. This was facilitated by lighting systems integrated within the measurement instruments (SP). Such controlled environments guaranteed that the spectral data collected was accurate and consistent across all subjects and datasets.During the measurement, the portable spectrophotometer was brought to the subject, ensuring the sample area had no blemishes (e.g. hair, freckles, etc.) and had not been subjected to recent pressure (e.g. to promote blood flow). Areas with visible hair (e.g., the chin of male participants with beards) were avoided during measurements to ensure that only clear skin areas were included in the dataset. When using a spectrophotometer, care was taken to ensure the instrument was gently in contact with the area of skin to be measured, to prevent extraneous light from reaching the detector (see Figure 1b). It was also necessary to be careful that no excessive pressure was applied to the skin when contacting the device, which might lead to a change in its colour due to the promotion of blood flow beneath the surface. Measurement parameters mentioned in the last section, such as the geometry of illumination and the inclusion of the specular component, must be checked before measurement. Measurements were taken at 4-10 different body locations depending on the site, with the forehead, cheek, and back of the hand covered by all sites. For consistency, measurements were taken from one randomly selected side (left or right) of each subject. Laterality was generally not recorded, except for Datasets 7 and 8, which included bilateral cheek measurements.After completing the measurements, we reviewed the data and excluded any measurements with zero reflectance (e.g., due to instrument error) or any participant data with colour difference greater than 15 ∆E_ab^* between positions. All measurement data were then carefully recorded and reported in accordance with the predefined coding schemes. This protocol not only supports the reliability of our measurements but also enhances the comparability of our data across various locations and time periods.<b>Citing the Database</b>Any use of the LSDB should cite the following reference: Lu, Yan; Xiao, Kaida; Pointer, Michael; He, Ruili; Zhou, Sicong; Nasseraldin, Ahmed; et al. (2025). The International Skin Spectra Archive (ISSA): a multicultural human skin phenotype and colour spectra collection. figshare. Dataset. https://doi.org/10.6084/m9.figshare.28228571<b>Contact the Author</b>Support and Contact Information: For technical support or queries related to the database, please contact Prof. Kaida Xiao ([e-mail]) and Dr Yan Lu ([e-mail]).<br><b>引言</b>国际皮肤光谱档案库（International Skin Spectra Archive, ISSA）提供了详尽的人类皮肤光谱与比色数据集合，涵盖来自2113名受试者的15256条记录。该数据集的时间跨度为2012年至2024年，数据来源于8个国家的11个由国际实验室整理的数据集，涉及英国、西班牙、中国、日本、巴基斯坦、泰国、伊拉克以及沙特阿拉伯。所有数据集均遵循标准化测量规程以保障数据一致性。 在ISSA数据集中，单条记录包含丰富的详细信息，包括记录编号、数据来源、受试者标识以及按种族、性别、年龄和身体部位分类的皮肤类型。数据集还涵盖了所用测量仪器的详细信息，如仪器类型、是否包含镜面反射分量、波长范围与波长间隔。 除光谱数据外，每份样本还包含基于CIE 1931标准色度观察者与CIE标准照明体D65的CIE比色数据，包括三刺激值、xy色度坐标、CIELAB参数等。 <b>数据记录</b>本数据集分为两个主要电子表格：编码表与数据表。数据表的列标识范围为A至BQ： A：唯一记录标识符 B：数据来源（关联至编码表中的来源表） C：受试者编号 D至G列：种族、性别、年龄组与身体部位（各列均关联至编码表中的对应参考表） H至L列：仪器详情，包括仪器类型与光谱测量参数 N至BD列：360 nm至780 nm波段的光谱数据 BF至BQ列：CIE比色数据 该结构化格式可使用户轻松获取并解读数据，适配多样的研究应用场景。 <b>测量规程</b>受试者的国籍/种族、性别、年龄与身体部位是影响人类皮肤颜色测量的关键因素，需根据具体研究需求确定。因此，每位参与者的相关信息首先通过问卷自评完成。在人口同质化的地区（如中国、泰国、日本），所有参与者均属于同一民族；在人口多元化的地区（如英国），问卷提供了现有民族、混合民族以及“其他（自定义）”的选项。这些信息通过数据集内统一的编码方案进行记录。 为保障本研究中所有皮肤光谱反射率测量的完整性与一致性，严格遵循多项标准化条件。首先，所有受试者的皮肤需保持清洁、无擦伤，且未涂抹任何可能影响测量结果的化妆品、乳液或医用产品。在数据采集前，每位受试者均需按此标准做好准备。此外，每轮测量前均需按照制造商指南对测量仪器（便携式分光光度计，portable spectrophotometer, SP）进行校准。测量时的光照条件需严格控制：所有测量均在漫射光照条件下进行，以避免平行光源带来的测量偏差，这可通过集成在测量仪器（SP）内的照明系统实现。此类受控环境可确保采集的光谱数据在所有受试者与数据集间保持准确一致。 测量过程中，需将便携式分光光度计移至受试者皮肤处，确保测量区域无瑕疵（如毛发、雀斑等）且未受近期压迫（如为促进血液循环而施加的压力）。需避开带有可见毛发的区域（如留胡须男性的下巴区域），以确保仅将清晰的皮肤区域纳入数据集。使用分光光度计时，需轻柔地将仪器贴合至待测皮肤区域，防止杂光进入探测器（详见图1b）。同时需注意，切勿对皮肤施加过大压力，以免因皮肤表层下血液循环变化导致肤色改变。测量前需检查前文提及的测量参数，如照明几何构型与是否包含镜面反射分量。根据测量部位的不同，需在4至10个不同身体部位进行测量，其中前额、脸颊与手背为所有测量部位均覆盖的区域。为保证一致性，每位受试者仅选取单侧（左侧或右侧）进行测量，通常不记录偏侧性信息，但数据集7与8除外，二者包含双侧脸颊的测量数据。 测量完成后，需对数据进行审核，剔除所有反射率为零的测量结果（如因仪器故障导致），以及任意部位间色差大于15 ΔE_ab^*的受试者数据。随后，所有测量数据均需按照预定义的编码方案进行细致记录与上报。该规程不仅保障了测量结果的可靠性，还提升了不同地域与时间跨度下的数据可比性。 <b>引用该数据库</b>使用本数据库需引用以下参考文献：Lu, Yan; Xiao, Kaida; Pointer, Michael; He, Ruili; Zhou, Sicong; Nasseraldin, Ahmed; 等. (2025). 国际皮肤光谱档案库（ISSA）：多族群人类皮肤表型与光谱颜色数据集. figshare. 数据集. https://doi.org/10.6084/m9.figshare.28228571 <b>联系作者</b>技术支持与联系方式：若需获取数据库相关的技术支持或咨询，请联系Kaida Xiao教授（[e-mail]）与Yan Lu博士（[e-mail]）。