Description of the parameters
For the specification of asymmetry, axes are laid at a close distance over the middle point of the lesion. For each of these axes the correlation for the lesions on both sides of the axis are measured. This correlation is used as the measurement of symmetry. As well as the symmetry axis, the angle dependent symmetry value is displayed in the middle of the lesion. The greater the symmetry, the larger the cross section of the blue region of this angle.
In many cases lesions have a diffused frame. Thus, through the software algorithm a simple border is drawn as well as an outlined area, whose width is dependent on sharpness. For the determination of border sharpness as a measurement of boundary, the initially calculated border is compared with a smoothed border. The border sharpness is drawn in as transparent shadowing. The wider the drawn in border shadowing is, the sharper the border on this position.
The absolute measurement of color parameters is less meaningful, since the skin color can change depending on tanning or other exogenous factors. Thus, the parameters for color variability, gray veil and decentral hyperpigmentation are determined relatively. The rotating RGB Diagram (button 3D-display) serves for a 3D display of color distribution. In this diagram the red, green and blue parts for each image point are removed. The color distribution for Nevus often appears as a narrow tube. In the case of melanoma this tube is normally wider and dilates towards the other side of the border.
Like with asymmetry, axes are laid through the middle point of the lesion for the determination of the maximum diameter. The outermost border is used for the determination of the diameter for all axes.
The software evaluates structural characteristics for detection of network structures. Detected network structures are marked in yellow. From these markings network structures a parameter is calculated which allows for a differentiation of typical and atypical pigment networks.