Mean surface brigthness within 25 mag isophot (B-band): bri25

bri25 (or amp25) is the apparent brightness : B + 5logD +3.63 + as

where B is the apparent magnitude in the B-band, logD is the logd25 diameter and
as is the inclination correction in magnitude per squared arcsec and is calculated as given below:

R is the axis ratio derived from logr25

k is the bulge to disk ratio and depends on morphological type as follows: k=0.754*10(-0.2*t), if  k >1 then k=1 (Simien and de Vaucouleurs)
K is the coefficient dlogD/db (where D is the isophotal diameter at surface brightness b). It depends on the morphological type t as:
K = 0.12-0.007*t  if  t < 0.
K = 0.094  if  t >= 0.

and C is defined as (dlogD/dlogR) and has the fixed value of 0.04 according to Bottinelli et al. 1995, A&A296, 64.