	US 12,254,639 B2
	Method for determining boundaries of a z-stack of images of an object, corresponding optical instrument and computer program therefor
Jose Miguel Serra Lleti, Wetzlar (DE); and Tobias Hessler, Wetzlar (DE)
Assigned to LEICA MICROSYSTEMS CMS GMBH, Wetzlar (DE)
Filed by Leica Microsystems CMS GmbH, Wetzlar (DE)
Filed on Dec. 9, 2022, as Appl. No. 18/063,691.
Claims priority of application No. 21214515 (EP), filed on Dec. 14, 2021.
Prior Publication US 2023/0186483 A1, Jun. 15, 2023
Int. Cl. G06T 7/13 (2017.01); G02B 21/24 (2006.01)

CPC G06T 7/13 (2017.01) [G02B 21/244 (2013.01); G06T 2207/10056 (2013.01)]

18 Claims

1. A method of automatically determining boundaries of a z-stack of images of an object, which z-stack of the images is to be acquired by imaging the object at a plurality of different focal positions by an optical instrument, the optical instrument comprising instrument optics and a focus adjusting unit for imaging the object at the plurality of different focal positions through the instrument optics, the method comprising the steps of:

generating a set of images of the object, each image being captured at a different respective focal position;

applying a blurriness-W metric function to each image of the set of images, wherein the blurriness-W metric function is a blurriness or sharpness metric function that has a focal position as a variable and shows a global extremum for maximal or minimal sharpness at the focal position, and additionally shows secondary extrema adjoining the global extremum;

calculating, by the blurriness-W metric function, a metric value for each image, different metric values being associated to a different image sharpness or blurriness of the corresponding images; and

based on the blurriness-W metric function with the focal position as a variable 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.