The LOOK algorithm, similar to the SCAN algorithm, honors requests on both sweep directions of the disk head, however, it additionally "looks" ahead to see if there are any requests pending in the direction of head movement.
[1] LOOK avoids the starvation problem of shortest seek time first (SSTF).
This is because LOOK is biased against the area recently traversed, and favors tracks clustered at the outermost and innermost edges of the platter.
It is an effort to remove the bias in LOOK for track clusters at the edges of the platter.
The huge jump from one end request to the other is not considered as a head movement as the cylinders are treated as a circular list.
Even through the average number of tracks traversed is the same as LOOK in the worst case, N and F LOOK are in some sense, more fair than plain old LOOK.