ANOVA results with estimated parameters from the reduced additive GAM model (per storage and fixative fluids on the whole). The first row represents the “golden standard” treatment, and the intercept value of the contrast luminosity (difference between dark and light areas) the other values are compared to. The “Estimate” column represents the difference between the intercept and the respective fluid on the whole, with values above zero signifying higher contrast and below zero lower contrast. The remaining columns test if that difference was statistically significant (*** = P ≤ 0.001, ** = P ≤ 0.01, * = P ≤ 0.05, . = ≤ 0.1). Results of the approximate significance of smooth terms are not shown, as they were all justified