I'm looking for ways to set up a phase contrast microscope to reduce the brightness gradient that appears across the background of my images.
I use phase contrast to find the outlines of cells in my images. My problem is that the automated processing algorithms I use get confused by strong brightness gradients in some images. Post-processing of the images disrupts the continuous nature of the histogram, again throwing off the algorithms.
Does anyone know why these gradients appear and how to reduce their formation?
Edited the question to clarify that I am interested in microscope usage, rather than image manipulation
The image background is darker at the left of the image than at the right