Algorithm 2. Pseudocode for the compressor part of the proposed lossless compression.

Input: $x$ // hyperspectral data Outputs: vecRice, // a vector that stores the calculated seed values. vecFrac, // a vector that stores the calculated fractions. vecRLE, // a vector that holds the counts of consecutive runs of zero and nonzero values. vecUnary. // a vector that holds the variable unary codes corresponding to the number of bits of each count. Initializations: $x_0\leftarrow 0$$, // \mathrm{the} \mathrm{initial} \mathrm{value} \mathrm{to} \mathrm{be} \mathrm{XORed} \mathrm{with} \mathrm{the} \mathrm{first} \mathrm{element} \mathrm{of} x$. ${nZ}_0\leftarrow 0$, // initialize the first nonzero value with 0. $cnt\leftarrow 1$, // counts the number of consecutive runs. $PO2\leftarrow 2$, // to calculate the required number of bits for each run. $nVar\leftarrow 11$, // the required number of bits for each run. $n\leftarrow$$\mathrm{the} \mathrm{number} \mathrm{of} \mathrm{bits} \mathrm{required} \mathrm{to} \mathrm{represent} x$. $\mathrm{done} \leftarrow 0$ For all $x_i$$\mathrm{in} x$ Do 1. Preprocessing $xored \leftarrow x_i \oplus x_{i-1}$ // perform exclusive-or operation. If $xored>0$ Then ${nZ}_i\leftarrow 1$ 2. Calculation of the integral part $MSH\leftarrow$$\mathrm{the} \mathrm{leftmost} \lceil n/2\rceil$$\mathrm{bits} \mathrm{of} xored$ $$Q\leftarrow 2^{⌊n/2⌋}$$ $seed\leftarrow (MSH+Q)\gg 1$ $riceCode\leftarrow \mathrm{m}\mathrm{a}\mathrm{p}\mathrm{p}\mathrm{e}\mathrm{d}\mathrm{R}\mathrm{i}\mathrm{c}\mathrm{e}\left(seed\right)$ $\mathrm{vecRice}.\mathrm{add}(riceCode$) 3. Calculation of the fractional part $m\leftarrow ⌈{\log }_2\left(2\cdot seed\right)⌉$ $Fr\leftarrow xored-{seed}^2$ // The fraction encoded as the distance between the xored value and the squared value of the seed         If $Fr>0$ Then         $Fr \leftarrow Fr-1$         Else         $Fr \leftarrow \mathrm{U}\mathrm{n}\mathrm{a}\mathrm{r}\mathrm{y}\left(seed\right)$         $seed \leftarrow 0$         End If ${Fr}_{out}\leftarrow$ $\mathrm{the} \mathrm{rightmost} m$$\mathrm{bits} \mathrm{of} Fr$ $\mathrm{vecFr}.\mathrm{add}({Fr}_{out}$) Else ${nZ}_i\leftarrow 0$ End If 4. Run length encoding of $\mathit{n}\mathit{Z}$ If ${nZ}_i={nZ}_{i-1}$ Then $cnt\leftarrow cnt+1$         If $cnt=PO2$ Then         $PO2 \leftarrow PO2\ll$ 1         $nVar\leftarrow nVar+1$         End If Else $\mathrm{vecRLE}.\mathrm{add}(cnt$) $\mathrm{vecUnary}.\mathrm{add}(nVar$) $cnt \leftarrow 1$ $PO2 \leftarrow 2$ End If End Do If done Then $\mathrm{vecRLE}.\mathrm{add}(cnt$) $\mathrm{vecUnary}.\mathrm{add}(nVar$) End If