Abstract: Sample regions of interest (ROIs) for use in autofocus procedures are identified based on a gradient image of the sample. ROIs with gradient values greater that a threshold are selected, and eigenvalues of the associated image matrices are determined. ROIs with suitable variation in eigenvalues such as at least two relatively large eigenvalues are associated with high contrast features orientated in multiple directions so that such ROIs are suitable for automatic focus and astigmatism correction. Suitable ROIs can also be identified based on a histogram of gradient orientations.

Abstract: Methods and systems for allowing users operators to quickly and easily (i) review the products of machine learning algorithm(s) to evaluate their accuracy, (ii) make corrections to such products, and (iii) compile feedback for retraining the algorithm(s) are disclosed. An example method includes acquiring a plurality of correlated images of a sample, determining one or more features in each image of the plurality of correlated images, and then determining a relationship between at least a first feature in a first image of the plurality of correlated images and at least a second feature in a second image of the plurality of images.