Is it an excessive pre-processing step in image processing?
I cannot access the raw images, so I did not test the algorithm. Note the aim of pre-processing is to increase the cell contrast to the background. You can remove one step from 2-6 each time to observe the background segmentation effect. By this means you may determine what steps play critical roles on the accurate cell boundary extraction and what others are not necessary. Mostly morphological operations plus sobel filters should be sufficient.