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Proceedings Paper

FPGA implementation of the pixel purity index algorithm
Author(s): Dominique D. Lavenier; James P. Theiler; John J. Szymanski; Maya Gokhale; Janette R. Frigo
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Paper Abstract

The Pixel Purity Index (PPI) is an algorithm employed in remote sensing for analyzing hyperspectral images. Particularly for low-resolution imagery, a single pixel usually covers several different materials, and its observed spectrum is (to a good approximation) a linear combination of a few pure spectral shapes. The PPI algorithm tries to identify these pure spectra by assigning a pixel purity index to each pixel in the image; the spectra for those pixels with a high index value are candidates for basis elements in the image decomposition. The PPI algorithm is extremely time consuming but is a good candidate for parallel hardware implementation due to its high volume of independent dot-product calculations. This article presents two parallel architectures we have developed and implemented on the Wildforce board. The first one is based on bit-serial arithmetic operators and the second deals with standard operators. Speed-up factors of up to 80 have been measured for these hand-coded architectures. In addition,the second version has been synthesized with the Streams-C compiler. The compiler translates a high level algorithm expressed in a parallel C extension into synthesizable VHDL. This comparison provides an interesting way of estimating the tradeoff between a traditional approach which tailors the design to get optimal performance and a fully automatic approach which aims to generate a correct design in minimal time.

Paper Details

Date Published: 6 October 2000
PDF: 12 pages
Proc. SPIE 4212, Reconfigurable Technology: FPGAs for Computing and Applications II, (6 October 2000); doi: 10.1117/12.402525
Show Author Affiliations
Dominique D. Lavenier, Los Alamos National Lab. (United States)
James P. Theiler, Los Alamos National Lab. (United States)
John J. Szymanski, Los Alamos National Lab. (United States)
Maya Gokhale, Los Alamos National Lab. (United States)
Janette R. Frigo, Los Alamos National Lab. (United States)

Published in SPIE Proceedings Vol. 4212:
Reconfigurable Technology: FPGAs for Computing and Applications II
John Schewel; Peter M. Athanas; Chris H. Dick; John T. McHenry, Editor(s)

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