Design and characterization of a LED-based multispectral imaging system applied to dermatology

Multispectral imaging technique has been used for skin analysis, especially for in-vivo non contact mapping of skin's chromophores. It is implemented by analyzing spectral cube data, i.e. a spatial image data that are taken at different wavelength. The acquired cube data is then used to construct 2-D maps of the distributed concentrations of chromophores, i.e. oxy-/deoxy-haemoglobin and melanin. The developmental goal of measurement device is to help dermatologist with an accurate tool for perform analysis on patient's skin condition. In this paper efforts to develope and characterize a new multispectral imaging (MSI) system for dermatology application will be described. The system developed system is operated using 12 wavelengths between 350 and 970 nm, at an equally wavelength intervals. The system composed of two parts: i.e. a) the light source, constructed using LEDs with 12 different wavelenghts in an dome-shaped compartment, and b) a monochromatic 8-Bit CCD camera, equipped with C-Mount objective lens, for capturing skin images under different illuminating wavelengths. A dedicated software to control the system, i.e. for acquired and processing multispectral images, were developed based on GUI MATLAB. Characterization were done to examined the inherent properties of the developed multispectral system, both for the light source (spectral bands of the LEDs used) and for the camera (spatial uniformity, linearity, and resolution). The multispectral imaging system is capable to construct 2-D map of distributed concentrations of chromophores from a skin surface in less than 6 seconds, which is regarded as suitable for daily clinical practice.