This paper describes an experimental study of the use of thermal infrared (8 - 12<i>μm</i>) imaging applied to the problem of pedestrian tracking. Generally it was found that infrared images enable better image segmentation, but their tracking performance with current algorithms is poorer. Simple fusion of both types of images has produced some improvement in the segmentation step of the tracking algorithms. In addition to the specific experimental results, this paper also provides a useful set of practical factors that need to be taken into account when using thermal infrared imaging for surveillance applications under real-world conditions.
A novel approach for designing quasi non-diffracting beams is presented. When using these beams for scanning images, the resulting signals have low contrast levels that are maintained over distances far exceeding depth-of-focus distances obtainable with Gaussian beams. A system using two phase-only diffractive optics filters separated by a free space region is sufficient to generate such beams. Gerchberg-Saxton algorithms are applied for determining the phase functions necessary for transforming the input laser beam into the desired beam distribution. The characteristics of the beams are presented.
Barcode-enhanced documents are used in office automation and in applications involving shipping manifests, vehicle registration forms, photo-ID, etc. They consist of human readable text and machine readable barcodes, which duplicates the text in a secure machine-readable form. Two-dimensional barcodes are used when it is beneficial to encode a large amount of data. The advantage of barcode-enhanced document over OCR is that the rejection and misdecode rates are several orders of magnitude smaller. This paper analyzes the performance of 2-D barcode-enhanced documents, characterized by the rates of correct decode, rejection, and misdecode of the 2-D barcode. Primarily using PDF417 as an example, we show how these rates are determined by the parameters used in the encoding process and the decoder design, and from the environment. We find that in real-world applications the misdecode rates are extremely low, and thus for all practical purposes the limiting parameter is the rejection rate.
Beam waist shift in optimum focusing of Gaussian beams is investigated under different conditions. We show that the minimum spot size on a target is only distinct from the beam waist when the target distance is fixed and either the lens focal length, the input beam waist, or the wavelength is varied.