This paper gives a detailed description of the reduction of astrophysical parameters available through LEDA database for more than 100 000 galaxies. It is often required by users of LEDA who need a reference where the description of parameters reduction is given. Most of these reduction procedures were described in previous studies:
Here, we will summarize these reduction and give reductions for some additional parameters: morphological types and mean effective surface brightness.
Each forthcoming section will be devoted to a given class of parameter.