Oversampling

Oversampling is the ratio of pixel size to the size of a speckle or Shannon pixel. This is also directly related to the ratio between the object size and the resolution at the edge of the detector. Loosely speaking, the number of speckles in the 3D intensity volume is equal to the number of resolution elements used to describe the particle density in real space.

It is common to aim for an oversampling ratio of around 5-6 when deciding the experimental geometry. This strikes a balance between making the process of performing iterative phasing easier and not wasting computational and data storage resources.

If you find that your oversampling ratio is too high when running a simulation or analyzing experimental data with Dragonfly, you have a few options:

1. You can bin the detector, i.e. combine multiple pixels into a single super-pixel. When performing a simulation, this is done simply by reducing detsize and increasing pixsize by the same factor.
   For experimental data, this must be done during data conversion, and preferably after photon conversion to avoid increasing detector noise.

2. You can bring the detector closer and process only the central part of the detector. For simulations, this can be done by reducing detd and detsize.
   Obviously this cannot be done retrospectively in a real experiment, but this is something that can be taken into account when designing the experiment. One warning is that for detectors with a fixed-size beamstop or hole, this may result in losing more low-resolution data. Option 1 may be better suited if this is a concern.