Method for determining boundaries of a z-stack of images of an object, corresponding optical instrument and computer program therefor

Abstract

A method of automatically determining boundaries of a z-stack of images of an object, the z-stack of the images acquired by imaging the object at different focal positions, is provided. The method includes generating a set of images of the object, each image being captured at a different focal position, and applying a blurriness-W metric function to each image. The blurriness-W metric function is a blurriness or sharpness metric function having a focal position as a variable, and shows a global extremum for maximal or minimal sharpness at the focal position and secondary extrema adjoining the global extremum. The method includes calculating, by the blurriness-W metric function, a metric value for each image, and based on the blurriness-W metric function showing a primary extremum and two of the secondary extrema adjoining the primary extremum, determining the z-stack boundaries in dependence of the focal positions assigned to the two secondary extrema.