Publications

In this paper we address the problem of human posture classification, in particular focusing to an indoor surveillance application. The approach was initially inspired to a previous works of Haritaoglou et al. [5] that uses histogram projections to classify people’s posture. Projection histograms are here exploited as the main feature for the posture classification, but, differently from [5], we propose a supervised statistical learning phase to create probability maps adopted as posture templates. Moreover, camera calibration and homography are included to solve perspective problems and to improve the precision of the classification. Furthermore, we make use of a finite state machine to detect dangerous situations as falls and to activate a suitable alarm generator. The system works on-line on standard workstations with network cameras.

The aim of this study was to develop a computerized method for the identification and description of colour areas in melanocytic lesion images based on an approach mimicking the human perception of colours. A colour palette comprising six colour groups (black, dark brown, light brown, blue-grey, red and white) was created by selecting single colour components within melanocytic lesion images acquired using a digital videomicroscope, and was implemented in the image analysis program. For each colour region, the area, the distance from the lesion centroid, the spread, the colour area distribution in the internal and the external part of the lesion, and asymmetries were assessed on 604 melanocytic lesion images in our image database. Black, white and blue-grey colour areas were detected more frequently in melanomas compared with naevi. Moreover, significant differences in colour descriptors were observed for each colour group, showing that colour areas are more unevenly distributed in melanomas compared with naevi. Using a discriminant analysis approach, the extension of dark, white and blue-grey areas and some descriptors of the distribution of the colour areas were identified as the most relevant colour parameters for differentiating between benign and malignant lesions. In conclusion, our automatic procedure breaks down the image into the colour areas used in the clinical examination process, and also supplies a description of their extension and distribution, with parameters that correlate with the clinical concepts of regularity and homogeneity.

Background: Identification of dark areas inside a melanocytic lesion (ML) is of great importance for melanoma diagnosis, both during clinical examination and employing programs for automated image analysis. Objective: The aim of our study was to compare two different methods for the automated identification and description of dark areas in epiluminescence microscopy images of MLs and to evaluate their diagnostic capability. Methods: Two methods for the automated extraction of ´absolute´ (ADAs) and ´relative´ dark areas (RDAs) and a set of parameters for their description were developed and tested on 339 images of MLs acquired by means of a polarized-light videomicroscope. Results: Significant differences in dark area distribution between melanomas and nevi were observed employing both methods, permitting a good discrimination of MLs (diagnostic accuracy = 74.6 and 71.2% for ADAs and RDAs, respectively). Conclusions: Both methods for the automated identification of dark areas are useful for melanoma diagnosis and can be implemented in programs for image analysis. Copyright

In this work, we describe a technique to calibrate images for skin analysis in dermatology. Using a common reference we correct non-uniform illumination effects, give an estimation of the gamma correction and produce a XYZ conversion matrix. The final result is then reverted to a non standard RGB color space, built from the instrument images. In this way different instruments behave uniformly allowing colorimetric characterization, while improving the results of common algorithms. The proposed techniques should be the initial support for a distributed framework where dermatological images can be consistently compared.

Atypical nevi share some dermoscopic features with early melanoma, and computer elaboration of digital images could represent a useful support to diagnosis. The aim of our study was to automatically assess colors in atypical nevi, and to compare the data with those referring to clearly benign nevi and melanomas. Dermoscopic images of 459 melanocytic lesions, referring to 76 atypical nevi, 288 clearly benign nevi and 95 melanomas, were acquired by means of a digital videomicroscope (Videocap 100, DS-Medica, Italy) employing a 20-fold magnification. An image analysis program, based on an approach, which shares some similarities with the human perception of colors, was employed. For the evaluation of colors in melanocytic lesion images, the identification of the six main color groups (black, dark brown, light brown, red, white and blue-gray) and the numerical description of color areas were obtained. Black, white and blue-gray were more frequently found in atypical nevi than in clearly benign nevi, but less frequently than in melanomas. Color area values significantly differed between the three groups, showing increasing irregularity in color distribution from benign lesions to atypical nevi and melanomas. The clinical–morphological interpretation of the numerical data, based on the mathematical description of the aspect and distribution of different color areas in different lesion types may contribute to the characterization of atypical nevi and their distinction from melanomas.

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Spitz nevi may be often confused with malignant melanoma, because of its rapid growth and alarming clinical features. In vivo confocal reflectance microscopy (CRM) is a novel technique enabling the noninvasive imaging of the skin at a cellular level resolution. Twelve Spitz and 25 melanomas (MMs) were studied by means of CRM (Vivascope 1000, Lucid Inc., USA) and digital dermoscopy (Videocap 200, DS-Mediroup, Italy) for in vivo characterization of cytological and architectural features at CRM, and correlation with dermoscopy and histology. Although large cells with bright cytoplasm and dark eccentric nucleus, sometimes spreading upwards in a pagetoid fashion, were observed both in Spitz nevi and MMs, in the latter case they were more numerous and irregularly shaped. Dermoscopic globules corresponded to cell clusters at CRM and melanocytic nests at histopathology. Spitz nevi frequently presented a peripheral rim of medium sized peripheral clusters, constituted by compact aggregates of large polygonal cells, sometimes observable also on the whole lesion area. In MMs cell clusters were frequently constituted by sparse cells intercalated with thin fibrils giving a multi-lobate appearance or by large confluent aggregates of low reflecting polygonal or elongated cells, resulting in a cerebriform appearance. Although CRM appeared useful for distinction between melanocytic lesions, Spitz nevi presenting numerous atypical cells and dermal-epidermal architecture disarrangement can not be always distinguished from MMs, owing to the limited penetration of the near-infrared laser light, not enabling the evaluation of ‘cell maturation’ with increasing depth.

Confocal reflectance microscopy (CRM) enables the in-vivo observation of the skin at a nearly histologic resolution. Since melanin represents a strong source of contrast, this technique appeared particularly indicated for the study of melanocytic lesions. Cytological and architectural features of melanocytic skin lesions were studied on 25 melanomas and 50 atypical melanocytic nevi employing CRM (Vivascope 1000, Lucid Inc., USA) and digital dermoscopy (Videocap 200, DS-Mediroup, Italy). All lesions were excised for diagnostic confirmation. Some differences in CRM features were observed between benign and malignant lesions: in melanocytic nevi, cells were usually round to oval, mainly located in the basal layers or clustered into nests within the papillary dermis. Melanomas were characterized by numerous large cells within the superficial layers of the epidermis, suggesting a pagetoid fashion, and by cells polymorphic in size and shape mainly located in the basal layer, sometimes interrupted by small dermal papillae irregularly distributed throughout the lesion, owing to disarrangement of the normal architecture of the rete ridges. Moreover, large irregular cells with refractive cytoplasm and eccentric dark nucleus infiltrating dermal papilla and cell clusters with a multilobulated feature constituted by sparse cells or with a cerebriform aspect were specifically observed in melanomas. Although preliminary and based on a limited number of cases, these findings show the potential of this technique for the noninvasive diagnosis of clinically difficult lesions.

Background: Spitz nevus is a benign melanocytic lesion sometimes mistakenly diagnosed clinically as melanoma. Objective: Our aim was to evaluate in vivo reflectance-mode confocal scanning laser microscopy (CSLM) aspects of globular Spitz nevi and to correlate them with those of surface microscopy and histopathology. Methods: A total of 6 Spitz nevi, with globular aspects on epiluminescence observation, were imaged with CSLM and subsequently excised for histopathologic examination. Results: A close correlation among CSLM, epiluminescence, and histopathologic aspects was observed. Individual cells, observed in high-resolution confocal images, were similar in shape and dimension to the histopathologic ones. Lesion architecture was described on reconstructed CSLM images. Melanocytic nests corresponded to globular cellular aggregates at confocal microscopy and to globules at epiluminescence observation. Melanophages were clearly identified in the papillary dermis both by confocal microscopy and histopathology. Conclusion: In vivo CSLM enabled the identification of characteristic cytologic and architectural aspects of Spitz nevi, correlated with histopathology and epiluminescence microscopy observation.