Application of photometric stereo in dermatology

Skin Analyser


To develop a vision system capable of assessing the malignancy of skin lesions and permitting tele-dermatogy for remote diagnosis.


The centre for machine vision has developed a handheld scanner for capturing both 3D and 2D data on skin lesions. The primary application area is in the assistance of the diagnosis of melanoma.

photometric stereo, bump map generation The tool is to be used to inspect the skin via local or remote terminals. It produces images through a combination of photometric stereo, bump map generation and perspective projection. An example of the captured image set is shown here. Application of photometric stereo methods yields the results shown to the right of the figure, i.e. the field of surface normals, the albedo map and the bump map.

Feature extraction

Characterizing the skin by using images obtained with the device is an indispensable intermediate step in this project. Good features extracted from geometric or colour information should be invariant or almost invariant to object position and pose, lighting condition and camera setup. Features might include asymmetry, border, colour variation, and diameter which are summarized as ABCD features.

As an example Skinof feature extraction consider these two figures. To the left is a picture of a real skin sample. The right shows a skin pattern isolated using image processing techniques.

Classifier building

Building a classifier is to combine several heuristic rules together used by the dermatologists to identify malignant melanoma. MelanomaThe ABCD rules might be simple and inaccurate if treated separately. But by combining them together using techniques like boosting, the final classifier would be highly accurate and has a good generalization capability. The image here illustrates an effort to isolate suspicious regions of a lesion. In the future, these regions will be detected and analysed robustly, using our classifier algorithm.

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Theme Leader

Centre for Machine Vision

Professor Melvyn Smith
Bristol Robotics Laboratory,
University of the West of England,
Frenchay Campus, T Building,
Coldharbour Lane,
Bristol, BS16 1QY
Tel: +44 (0)117 32 86358

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Page last updated 12 May 2016