Non-Invasive Skin Color Measurement
In dermatologic practice and clinical research, visual cues such as color are of primary importance for the accurate diagnosis and grading of skin lesions. Quantification of erythema and pigmentation is important for in vivo assessment of skin reactions to external stimuli such as ultraviolet radiation. Measurement of lesion color is also useful for quantitative evaluation of the efficacy of therapies for skin lesions.
However, visual inspection is a matter of perception and subjective interpretation and hardly quantifiable. This is because there is such a wide variety of ways to express a color which make describing a color or color difference extremely difficult and vague. In spite of the ability of human eyes to recognise up to millions of colors, we are unable to precisely quantify our color perception without instrumental means. Therefore, there is a need for objective, science based and non-invasive quantification of skin color or the extent of erythema and pigmentation.
Konica Minolta chromameters or spectrophotometers are usually used for the observation of skin color. To quantify the changes in skin color, the CIE L*a*b* color system is often used. The L*a*b* parameters provide a measure of the perception of skin color and can therefore emulate how the dermatologist or the average person perceive skin tones.
The L*, b* values are often used to evaluate the amount of epidermal melanin, while the a* value is used to evaluate the amount of erythema (also referred as haemoglobin) in the superficial plexus. In an attempt to quantitate skin pigmentation, the ‘Individual Typology Angle (ITA)’ or ‘Alpha Characteristic Angle’ haves been proposed.
Erythema and melanin indices are the indicators that quantify the intensity of erythema and pigmentation, respectively. These indices are derived from reflectance data of the skin at selected spectral bands. Unlike color coordinates, these indices are designed to show quantities that correlate linearly with the amounts of haemoglobin and melanin in the skin. Therefore, they can be handled as genuine physical quantities.
The main advantage of using Konica Minolta Spectrophotometer with Skin Analysis Software CM-SA over the conventional narrow-band simple reflectance meters is its capability to provide both colorimetric data (i.e., L*a*b*), as well as, the melanin and haemoglobin indices.
To know about CIE L*a*b* color system, ITA, haemoglobin and melanin indices, click here to download the white paper on “Non-Invasive Skin Color Measurement”. You can also contact us at +65 6895 8685 or write to us at ssg@gcp.konicaminolta.com.
