| classes: text, horiz.line, graphic, vert.line,picture
1,2,3,4,5

height:   continuous.    | Height of the block.
lenght:   continuous.    | Length of the block. 
area:     continuous.    | Area of the block (height * lenght);
eccen:    continuous.    | Eccentricity of the block (lenght / height);
p_black:  continuous.    | Percentage of black pixels within the block (blackpix / area);
p_and:    continuous.    | Percentage of black pixels after the application of the Run Length Smoothing Algorithm (RLSA) (blackand / area);
mean_tr:  continuous.    | Mean number of white-black transitions (blackpix / wb_trans);
blackpix: continuous.    | Total number of black pixels in the original bitmap of the block.
blackand: continuous.    | Total number of black pixels in the bitmap of the block after the RLSA.
wb_trans: continuous.    | Number of white-black transitions in the original bitmap of the block.