The Wiktionary lists 14 separate definitions for "resolution". In microscopy resolution is mostly related to the ability of the optical system to separate fine features clearly. In photography, resolution is used to measure the number of pixels in a camera sensor. In Imaging, resolution is something in between. It is formally defined as "the ability to separate the constituent parts of a whole".

In imaging, resolution is mostly defined by the following 4 factors:

1. Optical resolution - how finely the optics separate points of light from their neighbors
2. Sampling resolution - how finely the pixels on the camera sensor are separated
3. Signal-to-noise ratio - how much light are we collecting compared to the noise generated by the system
4. The bit depth of the imaging sensor - the degrees of separation between the minimum and maximum value recorded by the imaging device