MA_MISS: EVALUATION OF COMPRESSION FACTOR WITH RICE SOFTWARE BY MEANS OF THE ESA WHITEDWARF TOOL

Abstract

This document reports on the results of some tests performed to evaluate data compression factors achieved with the ESA WhiteDwarf tool, based on RICE compression algorithm. In order to test the WhiteDwarf tool, three different kinds of data have been used: 1) MA_MISS simulated data, see Table 1A (simulated dark) and 1B (dark from PRISMA); 2) PRISMA data, see Table 2; 3) VIR/Dawn data (single slices or whole cubes), see Table 3A (VIR-VIS channel) and Table 3B (VIR-IR channel). Results show that the highest values for the compression factor are found for the dark signals of the PRISMA sensor and VIR-VIS channel, 2.2 and 4.8 respectively. As far as the signal (both simulated and observed) is concerned, the compression factor ranges between 1.3 and 2. Factor 2 is found for the VIR- VIS data, where a more homogenous signal is observed. Factor 1.3 is found for the VIR-IR data, where a higher spectral variability is found. The subtraction of the dark in the signal before performing the compression can increase the compression factor, depending on the variability observed in the dark itself. Housekeeping (HK) data can also impact the compression factors. In order to simulate MA_MISS HK, sets of numbers have been generated randomly or with a low correlation. Tests performed including HK with no correlation (worst case) and of the order of 10% of the science data set, show compression factors varying in the same range of values of those found without considering the HK data (1.3 and 2). Tests have been performed considering data with 16 bits per sample, as the ESA tool does not allow to compress data with 24 or 32 bits per sample.