Controls the selection of seed objects for classification. The first component defines half-width of stellar objects band in a magnitude versus relative gradient plot. The second value sets an upper limit for relative gradient for seed galaxies. The third component tells how much brighter in magnitudes the seed objects should be in relation to the limiting magnitude. Recommended value is 5.0.
Smaller values increase execution time with only little improvement of accuracy.
Larger values may harm the accuracy. Recommended value is 0.02. Limiting distance in a parameters space for including object in a particular class of objects. Recommended value is 0.25. Petrosian -function used in the determination of the Petrosian radius and Petrosian magnitude.