Algorithm 4:

Require: 1 × 9 VRF signal array, $x\left[1\dots 9\right]$. Select the center value $c$ from the set of neighboring points. For each sample point, calculate the gradient value as $x\left[i\right]=\left|x\left[i\right]-c\right|$ for $i=0,1,2,\dots ,n$. Compare the continuous neighboring gradient point along with the center value $c$. If the adjacent point $x\left[i\right]$ is greater than or equal to $x\left[i+1\right]$ the value of 1 is set, otherwise 0 will be assigned. In the transformation step, the binary value is converted into decimal code. Compute the LNGP code.