The skin pigmentation attention is one of the most shared skin characteristics in the world. It evolves over time in various ways according to the several ethnic, social and cultural communities. And when it’s time to consider external influences, such as UV or pollution conditions associated with whitening or lightening activities, skin color becomes a real challenge for the objectivation manager.

What are the present technologies and instrumentation available to evaluate the skin color changes during in-vivo testing studies?

The skin color analysis is naturally implemented in the reflectance spectrum of the skin from 400 to 700 nm. The several devices use different light emission parameters: wavelengths, source of light (Xenon, Leds) and directions.

Generally, the quantity of emitted light is defined, and the quantity of light absorbed by the skin is also calculated. The color measurement is based on the evaluation of the 3 main and well-known color components L* (lightness from black to white), a* (green/red axe) and b* (blue/yellow axe). The ITA (Individual Typology Angle) can be also calculated.

The measure of the skin color is easy, fast, reproducible, and well established in the cosmetics evaluation. Various instrumentations can evaluate the color of the skin whether it is quantification or visualization.

You can find in the Clinical Testing platforms, all the instrumentation dedicated to the color measure of the skin, scalp, hair, nails, or teeth. The claims related to the pigmentation or color are numerous depending on the type of cosmetics purposes. These are numerous considering the variety in term of product category such as skin care, makeup, oral care, or haircare or texture, organoleptic parameters and treatment conditions.

Four main categories of performance linked to product categories have specific ways to be evaluated; let’s have a look:

1. Skincare and color parameters are linked to the skin conditions and its surface imperfections. It is summarized by the following claims per type of mechanisms:
   • For global imperfections: anti-blemish, anti-maskne, healthy skin, wound-healing, stretch-marks…
   • For microcirculation: Anti-couperose, anti-rosacea, anti-redness,
   • For ageing: Anti-brown spots, anti-dark circles,
   • For melanin and skin pigmentation or hyperpigmentation: lightening whitening, self-tanner, tan-activator…
   • For erythema or inflammation: Soothing effect, anti-inflammatory, CBD effect…
   • For radiance and complexion homogeneity.
2. Makeup & color evaluation will refer to makup lasting, long-lasting wear and waterresistance or mattifying, covering effect, transfer evaluation
3. Hair care & deying testing for their color characteristics and lasting under several conditions of treatment: Anti-grey hair, color lasting…
4. Oral care: gums and teeth color

The Clinical Testing Platform gathers at date

• 28 methods: Scoring by expert evaluation or quantification or visualization by instrumentation
• 21 devices
• 99 testing suppliers in 32 countries

You can consult for free all these information, https://skinobs.com/clinical.php whether it is by selecting the “category of tests” 3. Biometrology, or 4 or 6. then the “claims” you like to substantiate or directly the “type of analysis” you already know.

You can find 5 types of technologies measuring the skin color:

The direct and specific analysis of the color. The skin color analysis is naturally implemented in the reflectance spectrum of the skin from 400 to 700 nm. The several devices use different light emission parameters: wavelengths, source of light (Xenon, Leds) and directions. Generally, the quantity of emitted light is defined, and the quantity of light absorbed by the skin is also calculated.

The color measurement is based on the evaluation of the 3 main and well-known color components :

• L* (lightness from black to white),
• a* (green/red axe) and
• b* (blue/yellow axe).

The ITA (Individual Typology Angle) can be also calculated.

The instrumentations are: Chromameter, Spectro-colorimeter, Colorimeter (Courage & Khazaka),

The measure of the color including erythema, hemoglobin and melanin parameters is made using specific wavelengths to avoid other color influences: SkinColorcatch, DermaLab colormeter (Cortex Technology).Mexameter® MX 1 (Courage & Khazaka), SiaScope, TiVi 70 Skin Colour Tracker (Wheelsbridge)…

The direct but not specific instrumentations that analyse de skin surface and characterize by HD camera the skin color among other parameters are numerous. Each instrumentation has its own image acquisition specificities such as light, probes, sensors and always a dedicated software including algorithms, I.A (or not) and illustrative results to deliver precise information on the color of the skin: C-Cube (Pixience), Antera 3D [Miravex], SkinCam [Newtone Technologies]…are the main ones.

Then the last technology refers to global evaluation of the entire face using specific equipment that includes the measure of the skin color and erythema. These are: Visia-CR, Aeva-HE and EvaFace 5 [Eotech], HeadScan Dynamics and HeadScan V05 Research [Orion Technolab], VisioFace [Courage&Khazaka].

Finally, alternatives of classical skin color are given by high-tech visualization of melanosomes and pigments by confocal microscopy (Mavig, Michelson, Jenlab), but also by scoring from experts and auto-evaluation questionnaire combined with biometrological measure.

The challenges of color measure are the room environments of the light but also the humidity and the temperature, and the reproducibility of the measure location. The use of a specific bench guaranties the accuracy of the measurements. Thus, data treatment should be considered also and characterized as I.A results or classical algorithms. The evolution of technology in the no contact probe, the data acquisition and treatment with the use of I.A algorithm may give the direction of non-contact and optical solutions. Today, the “must have” for the cosmetics brands and consumers is the illustrative results.

The preliminary discussion with the CROs to design the study (timeline, duration, conditions of use of the products, inclusion criteria, instrumentation choice …), seems to be essential to define the best protocol to support the claim substantiation.

As conclusion, we could say that the big challenge for the evaluation of depigmenting, whitening, lightening or anti-spots….claims is to choose between measuring a small skin zone precisely and get data and analyzing a bigger skin zone with images analysis.