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A passive-polarization-based imaging system records the polarization state of light reflected by objects that are illuminated with an unpolarized and generally uncontrolled source. Such systems can be useful in many remote sensing applications including target detection, object segmentation, and material classification. We present a method to jointly estimate the complex index of refraction and the reflection angle (reflected zenith angle) of a target from multiple measurements collected by a passive polarimeter. An expression for the degree of polarization is derived from the microfacet polarimetric bidirectional reflectance model for the case of scattering in the plane of incidence. Using this expression, we develop a nonlinear least-squares estimation algorithm for extracting an apparent index of refraction and the reflection angle from a set of polarization measurements collected from multiple source positions. Computer simulation results show that the estimation accuracy generally improves with an increasing number of source position measurements. Laboratory results indicate that the proposed method is effective for recovering the reflection angle and that the estimated index of refraction provides a feature vector that is robust to the reflection angle. OCIS codes: 100.0100, 100.5010, 120.5410.

We consider here the implementation of efficient search and retrieval of digital elevation maps (DEMs), in particular the ability to conduct elevation searches without decompressing the entire map. We utilize set partitioning in hierarchical trees (SPIHT) for the compression, and compare two wavelet-based search and retrieval systems: one utilizing nonlinear max- and min-lifted integer wavelets and the other using the standard 5/3 integer wavelet. While the coarse-scale maxima/minima preservation inherent in the max- and min-lifted wavelets may seem ideal for the implementation of efficient elevation searches, the interscale propagation of maxima/minima and the bit-plane layering of the SPIHT coder adversely affect the efficiency of such searches. The use of the standard 5/3 integer wavelet requires the addition of separate maxima and minima information but does not have the complication of coefficient propagation, providing more satisfactory results. Elevation search bitrates are presented for both systems and compared to results obtained using the Kakadu implementation of the JPEG2000 standard. Index Terms--Digital elevation maps (DEMs), image browsing, max-lifted, nonlinear wavelets, search and retrieval lossless compression.

The author discusses image processing methods of creating reduced resolution versions of original images. The formation of an embedded coding algorithm that generates a compressed bit stream is analyzed.

A hybrid algorithm has been developed that draws on automatic target recognition/automatic target cueing (ATR/ATC) algorithms and regional embedded compression techniques. The regional compression algorithm expands available bandwidth by maximizing the information content of transmitted imagery. This technique could be valuable in the uncrewed aerial vehicle and uncrewed aerial combat vehicle arena.

There is interest in the transmission of image and video data over noisy communications channels, and it is often beneficial to combine the source and channel coding. A form of low-complexity joint source-channel coding, whereby differing amounts of transmission error robustness are built into an embedded bit stream, is introduced. The method is based on a modification of Shapiro's embedded zerotree wavelet (EZW) image compression algorithm.

A new design of high-quality prototype filters for M-band pseudo quadrature mirror filter (QMF) banks uses a method that optimizes a single parameter on a convex error surface. The method provides a good equiripple filter over a long time and minimizes the overlapped passband distortion. Traditional nonlinear optimization cannot be used in designing this method. The filter length does not affect the quality of the solution.