screenshots_output_mask
The option documentation is properly formatted yet
Default: 7 Example: 3 Since: 2.1.28
Selects what screenshot types to save. Add together the following values: 1 - save full frames, 2 - save cropped frames, 4 - store OpenGL screenshots. For example, to save full frames and cropped frames only, set the value to 3 (1 + 2).
Source: https://github.com/FrodeSolheim/fs-uae/blob/master/docs/options/screenshots_output_mask