Detecting drops on lens in wireless multimedia sensor network nodes

Guaranteeing the quality for images acquired by nodes of a Wireless Multimedia Sensor Network (WMSN) is a critical issue, especially in outdoor applications. In a distributed perspective, the node should promptly detect the deterioration of the quality of the acquired data and, whenever possible, react. This work addresses the problem of determining when a camera mounted on a WMSN node starts acquiring data corrupted because of a drop on the camera lens, which may frequently occur in outdoor deployments. The resulting images have been modeled as corrupted by a blurring operator that may affect the whole image or only in some areas. The monitoring of the degradation process is obtained by combining blur measurements from the acquired images with a change detection test to assess changes in the camera status. Both the blur measurements and the change detection test do not require any assumption about the image content or the blur characteristics hence making the suggested methodology rather effective in a large class of applications.