Parameter Abbr. Unit Interpretation
Mean biofilm thickness \({\overset{\overline{}}{L}}_{F}\) µm Biofilm height in z-direction; calculated from the bulk-biofilm interface to the substratum with neglection of pores
Substratum coverage SC % Coverage of the flow cell bottom with biofilm; 100 % minus this parameter would result in global porosity
Textural entropy TE - Is a measure of the randomness of the pixel intensity distribution and thus of the biofilm heterogeneity (raising values explain more heterogeneous biofilms)
Fractal dimension FD - Describes the irregularity of the aggregates‘ surfaces; higher values equal higher surface roughness’s
Skewness \(R_{\text{SK}}\) - Determines the occurrence of low (valleys; \(\backslash nR_{\text{SK}}\)<0) and high biofilm colonies (hills;\(\ R_{\text{SK}}\)>0) in the biofilm structure
Kurtosis \(R_{\text{KU}}\) - Defines the distribution of these occurred valleys and hills on the biofilms’ surface
Average second moment ASM - Direction orientated indicator of the cell clusters (higher values describe dimensional uniformity; lower values define a change in growth direction (x, y) of the biofilm aggregates)
Inverse difference moment IDM - Similar to ASM but distance orientated (lower values indicate that distances between biofilm aggregates decrease)
Average vertical run length AVRL µm Mean colony width in y-direction; calculated from separated biofilm aggregates in the flow channel
Average horizontal run length AHRL µm Mean colony length in x-direction; calculated from separated biofilm aggregates in the flow channel