On the hardware implementation of the arithmetic elements of the pairwise orthogonal transform

Abstract

The pairwise orthogonal transform (POT) is an attractive alternative to the Kahrunen-Loève transform for spectral decorrelation in on-board multispectral and hyperspectral image compression due to its reduced complexity. This work validates that the low complexity of the POT makes it feasible for a space-qualified field-programmable gate array (FPGA) implementation. A register transfer level description of the arithmetic elements of the POT is provided with the aim of achieving a low occupancy of resources and making it possible to synthesize the design on a space-qualified RTAX2000S and RTAX2000S-DSP. In order to accomplish these goals, the operations of the POT are fine-tuned such that their implementation footprint is minimized while providing equivalent coding performance. The most computationally demanding operations are solved by means of a lookup table. An additional contribution of this paper is a bit-exact description of the mathematical equations that are part of the transform, defined in such a way that they can be solved with integer arithmetic and implementations that can be easily cross-validated. Experimental results are presented, showing that it is feasible to implement the components of the POT on the mentioned FPGA