Feature Extraction and Pattern Recognition from Fisheye Images in the Spatial Domain

Feature extraction for pattern recognition is a very common task in image analysis and computer vision. Most of the work has been reported for images / image sequences acquired by perspective cameras. This paper discusses the algorithms for feature extraction and pattern recognition in images acquired by omnidirectional (fisheye) cameras. Work has been reported using operators in the frequency domain, which in the case of fisheye/omnidirectional images involves spherical harmonics. In this paper we review the recent literature, including relevant results from our team and state the position that features can be extracted from spherical images, by modifying the existing operators in the spatial domain, without the need to correct the image for distortions.