A parallax-based automatic focusing and focus locking method for a light field microscopy system, wherein the light field microscopy system comprises a microlens array configured for acquiring multi-view information of an image;
- and the method comprises following steps:
- a defocus coefficient matrix calibration step:
- shooting at a position of a defocus distance z of a sample by using the light field microscopy system, to obtain first two-dimensional original light field data containing four-dimensional information, and rearranging into first four-dimensional phase space data;
- calculating parallax of each view relative to a central view of the first four-dimensional phase space light field data by using cross-correlation, comprising:
- wherein the step of calculating parallax of each view relative to the central view of the first four-dimensional phase space light field data by using cross-correlation comprises:
- R
- u
- ,
- v
- (
- m
- ,
- n
- )
- =
- ∑
- x
- ∑
- y
- W
- 1
- (
- x
- ,
- y
- ,
- u
- ,
- v
- )
-
- W
- 1
- (
- x
- +
- m
- ,
- y
- +
- n
- ,
- u
- 0
- ,
- v
- 0
- )
- ;
- S
- 0
- (
- u
- ,
- v
- )
- =
- arg
-
- max
-
- R
- u
- ,
- v
- (
- m
- ,
- n
- )
- ;
- wherein u and v represent longitudinal and lateral angular coordinates of a single microlens respectively, value ranges of m and n are [0,w] and [0,h] respectively, h and w indicate a pixel height and a pixel width of each sub-image respectively, W1 indicates the first four-dimensional phase space data;
- and u0 and v0 represent longitudinal and lateral angular coordinates of the central view respectively;
- and
- calculating and obtaining a two-dimensional defocus coefficient matrix K of the light field microscopy system based on the parallaxes and the defocus distance z, comprising:
- dividing each of the parallaxes by the defocus distance z to calculate and obtain the two-dimensional defocus coefficient matrix K of the light field microscopy system;
- and
- a sample focusing and focus locking step:
- shooting the sample at a current shooting distance by using the light field microscopy system, to obtain second two-dimensional original light field data containing four-dimensional information;
- rearranging the second two-dimensional original light field data into second four-dimensional phase space data, and calculating parallax of each view relative to a central view of the second four-dimensional phase space data by using cross-correlation, to obtain a current two-dimensional parallax matrix S of the sample;
- performing linear fitting on the two-dimensional parallax matrix S and the two-dimensional defocus coefficient matrix K, to obtain a current defocus value of the sample;
- and
- adjusting the current shooting distance in real time according to the defocus value until focusing and/or focus locking is completed, comprising:
- determining whether the defocus value is equal to 0, wherein if yes, the sample is in a focal plane and the focusing is completed;
- and if not, the current shooting distance is adjusted according to the defocus value, and the sample focusing and focus locking step is executed repeatedly until the defocus value is equal to 0, then the focusing of the sample is completed.