Several characteristics of the dispered air bubbles in aerated concrete have been indicated as very im p o rta n t to the stu d y o f the fun ction o f en tra in ed air. This artic le describes the d iffe re n t stages in the processing o f images obtain ed fo r characterizing, among o th e r things, a functio n o f the a ir v o id ra tio, the highly variable dispersion of the parameters of spacing factor, the specific surface, the void frecuency, etc.. The results are compared with other methods, as Linear-transverse, using in the Standard test of ASTM C-457-90