done only at the resolution of the captured images. There are several shortcom-
ings associated with single-resolution techniques. First, noise in microscope
images largely manifests itself at the higher frequencies. Computing focus
measures on images at full resolution can produce a noisy autofocus function
and may lead to inaccurate determination of the in-focus position. Second, due
to the possibility of multiple peaks on noisy autofocus functions, fast search
algorithms may find a local maximum rather than the global maximum.
To avoid this, exhaustive search would have to be performed, and this requires
capturing and processing considerably more images along the z-axis. Such
a solution is unacceptable in exposure-sensitive applications. Photobleaching, ...