Automated region selection for auto sweep

A charged-particle beam (CPB) imaging system, comprising:

• a CPB optical column operable to direct a CPB to a sample and produce an image of at least a portion of a sample;
• and
• a system controller coupled to the CPB optical column and operable to shape and direct the CPB to the sample, wherein the system controller is configured to:
• process a sample image to obtain a gradient magnitude image;
• select a set of initial candidate regions of interest (ROIs) in the sample image associated with gradient magnitude image portions having gradient magnitudes greater than a threshold value;
• ranking each of the initial candidate ROIs;
• and
• selecting a ROI from the initial candidate ROIs based on the ranking, and adjusting focus and astigmatism based on the selected ROI.