Auto-focus methods and systems for digital imaging using multi-spectral trajectories

1. A method for acquiring focused images of a specimen on a slide, by determining optimal scanning trajectories, the method comprising:

capturing a relatively low magnification image of the slide to locate the specimen;

forming a grid that includes an arrangement of grid points;

overlaying at least part of the grid over a field of view that covers at least part of the specimen;

for each grid point within the at least part of the grid:

capturing a set of Z-stack images that correspond to the grid point;

computing an average gradient value for one or more image features of each image of the set of Z-stack images;

selecting an image from the set of Z-stack images having a greatest average gradient value; and

processing the image having the greatest average gradient value to generate a focus value corresponding to the grid point

using the focus value of each grid point within the at least part of the grid to form a resulting grid of three dimensional points; and

based on the resulting grid, determining one or more three dimensional scanning trajectories.

2. The method of claim 1 , wherein processing the image having the greatest average gradient value to generate the focus value corresponding to the grid point further includes discarding the set of Z-stack images following the generation of the focus value corresponding to the grid point.

3. The method of claim 1 , wherein the grid is formed in a two-dimensional plane; and

wherein capturing the set of Z-stack images includes using an optical beam that is perpendicular to the two-dimensional plane.

4. The method of claim 1 , further comprising:

capturing a focused image of a part of the specimen corresponding to each of the one or more three dimensional scanning trajectories; and

stitching the focused images of the parts of the specimen to obtain a composite image of an entire specimen.

5. The method of claim 3 , wherein the grid includes an even arrangement of grid points.

6. The method of claim 3 , wherein the grid includes an irregular arrangement of grid points.

7. The method of claim 3 , wherein said one or more three dimensional scanning trajectories include multi-spectral trajectories.

8. The method of claim 7 , wherein computing an average gradient value for each image of the set of Z-stack images comprises determining the average gradient value for each Z-value corresponding to grayscale and each color of interest of the grid point.

9. The method of claim 8 , further including remotely accessing and displaying any one or more of a gray-scale image, images of colors of interest, and/or a composite image of an entire specimen.

10. A system for acquiring focused images of a specimen on a slide, by determining optimal scanning trajectories, the system comprising:

a digital imager that captures a relatively low magnification image of the slide to locate the specimen; and

a digital imaging system that:

forms a grid comprised of an arrangement of grid points;

overlays at least part of the grid over a field of view that covers at least part of the specimen;

for each grid point within the at least part of the grid:

receives, from the digital imager, a set of Z-stack images that correspond to the grid point;

computes an average gradient value for one or more image features of each image of the set of Z-stack images;

selects an image from the set of Z-stack images having a greatest average gradient value; and

processes the image having the greatest average gradient value to generate a focus value corresponding to the grid point;

uses the focus value of each grid point within the at least part of the grid to form a resulting grid of three dimensional points; and

based on the resulting grid, determines one or more three dimensional scanning trajectories.

11. The system of claim 10 , wherein the digital imaging system discards the set of Z-stack images following the generation of the focus value corresponding to the grid point.

12. The system of claim 11 , wherein computing an average gradient value for each image of the set of Z-stack images comprises determining the average gradient value for each Z-value corresponding to grayscale and each color of interest of the grid point.

13. The system of claim 11 , further including a user station that remotely accesses and displays any one or more of a gray-scale image, images of colors of interest, and/or a composite image of an entire specimen.

14. A non-transitory computer-readable medium storing instructions which, when executed by one or more processors, cause a system for acquiring focused images of a specimen on a slide to perform operations comprising:

instructing a digital imager to capture a relatively low magnification image of the slide, in order to locate the specimen;

forming a grid comprised of an arrangement of grid points; overlaying at least part of the grid over a field of view that covers at least part of the specimen;

for each grid point of the at least part of the grid:

receiving, from the digital imager, a set of Z-stack images that correspond to the grid point;

computing an average gradient value for one or more image features of each image of the set of Z-stack images;

selecting an image from the set of Z-stack images having a greatest average gradient value; and

processing the image having the greatest average gradient value to generate a focus value corresponding to the grid point

using the focus value of each grid point within the at least part of the grid to form a resulting grid of three dimensional points; and

based on the resulting grid, determining one or more three dimensional scanning trajectories.

15. The non-transitory computer-readable medium of claim 14 , wherein

the operation to process the image having the greatest average gradient value to generate the focus value corresponding to the grid point further comprises discarding the set of Z-stack images following the generation of the focus value corresponding to the grid point.

16. The non-transitory computer-readable medium of claim 15 , wherein computing an average gradient value for each image of the set of Z-stack images comprises determining the average gradient value for each Z-value corresponding to grayscale and each color of interest of the grid point.

17. The non-transitory computer-readable medium of claim 15 , wherein the operations further comprise enabling a remotely located user station to access and display any one or more of a gray-scale image, images of colors of interest, and/or a composite image of an entire specimen.

18. The method of claim 1 , wherein the one or more image features correspond to a gray-scale color channel corresponding to the image of the set of Z-stack images.

19. The method of claim 1 , wherein the one or more image features correspond to a plurality of color channels corresponding to the image of the set of Z-stack images.

20. The non-transitory computer-readable medium of claim 14 , wherein the operations further comprise:

capturing a focused image of a part of the specimen corresponding to each of the one or more three dimensional scanning trajectories; and

stitching the focused images of the parts of the specimen to obtain a composite image of an entire specimen.