Correction of mis-focus in recorded images using centered discrete fractional fourier transformations with high-accuracy orthonormal eigenvectors

1. A method for correcting mis-focus of an image, the method comprising:

receiving an image file at a numerical processor, the image file comprising a portion of the image in an original mis-focused condition;

selecting a numerical value for a variable α;

beginning a first iteration of a numerical procedure executing on the numerical processor;

in the numerical procedure, applying a two-dimensional centered discrete fractional Fourier transform operator of power α to the image file and applying a phase correction operator associated with the two-dimensional centered discrete fractional Fourier transform matrix of power β−α to the image file;

obtaining a modified portion of the image file from the above operations;

inspecting the modified portion of the image file and determining a change in the mis-focused condition;

based on the determined change, adjusting numerical value of α; and

beginning a next iteration of the numerical procedure on the numerical processor;

wherein if numerical values for the variable α between the real values of 0 and β do not result in a desired outcome, the numerical value for the variable α is adjusted to an imaginary value of the form iχ where χ is the imaginary part of α.

2. The method of claim 1 , wherein the number β is real.

3. The method of claim 1 , wherein the two-dimensional centered discrete fractional Fourier transform comprises two one-dimensional centered discrete fractional Fourier transform matrices, each such that the power of α=η results in a centered discrete Fourier transform matrix and the power of α=β results in a reflection matrix.

4. The method of claim 3 , wherein the number η is real, and the reflection matrix reverses the sequence order of the elements of a vector on which the reflection matrix operates.

5. The method of claim 4 , wherein number η is 0.

6. The method of claim 1 , wherein the two-dimensional centered discrete fractional Fourier transform operator of power α is applied after applying the phase correction operator associated with a two-dimensional centered discrete fractional Fourier transform matrix of power β−α.

7. The method of claim 1 , wherein the two-dimensional centered discrete fractional Fourier transform operator of power α is applied before applying the phase correction operator associated with a two-dimensional centered discrete fractional Fourier transform matrix of power β−α.

8. The method of claim 1 , wherein number β is 2.

9. The method of claim 1 , wherein number χ is a positive number.

10. The method of claim 1 , wherein number χ is a negative number.

11. The method of claim 1 , wherein the image is an image created by coherent imaging.

12. The method of claim 1 , wherein the image is an image created by electron imaging.

13. The method of claim 1 , wherein the image is an image created by light imaging.

14. A method for correcting mis-focus of an image, the method comprising:

receiving an image file at a numerical processor, the image file comprising a portion of the image in an original mis-focused condition;

selecting a numerical value for a variable α;

beginning a first iteration of a numerical procedure executing on the numerical processor;

in the numerical procedure, applying a two-dimensional centered discrete fractional Fourier transform operator of power α to the image file and applying a phase correction operator associated with the two-dimensional centered discrete fractional Fourier transform matrix of power β−α to the image file;

obtaining a modified portion of the image file from the above operations;

inspecting the modified portion of the image file and determining a change in the mis-focused condition;

based on the determined change, adjusting numerical value of α; and

beginning a next iteration of the numerical procedure on the numerical processor; wherein if numerical values for the variable α between the real values of 0 and β do not result in a desired outcome, the numerical value for the variable α is adjusted to an imaginary value of the form iχ where χ is the imaginary part of α, wherein the two-dimensional centered discrete fractional Fourier transform operator is represented as a 4-dimensional array.

15. The method of claim 14 , wherein the two-dimensional centered discrete fractional Fourier transform operator is represented as a 4-dimensional tensor.

16. The method of claim 14 , wherein the two-dimensional centered discrete fractional Fourier transform operator is applied as a first one-dimensional centered discrete fractional Fourier transform matrix operating on columns of the image file and a second one-dimensional centered discrete fractional Fourier transform matrix operating on rows of the image file.

17. The method of claim 14 , wherein the phase correction operator is a 4-dimensional tensor.

18. The method of claim 14 , wherein the phase correction operator is a 4-dimensional array.

19. The method of claim 14 , wherein the phase correction is applied as a first one-dimensional phase correction operator matrix associated with a two-dimensional centered discrete fractional Fourier transform matrix of power β−α operating on columns of the at least portions of the image file and a second one-dimensional phase correction operator matrix associated with a two-dimensional centered discrete fractional Fourier transform matrix of power β−α operating on rows of the at least portions of the image file.

20. A method for correcting a mis-focus of image file created from coherent imaging using centered fractional Fourier transforms or mathematical equivalents, the method comprising:

receiving the mis-focused image at a numerical processor;

selecting a first numerical value for a variable α

iterating a numerical procedure using the variable α;

in the numerical procedure, applying a centered discrete fractional Fourier transform of power α and a phase restore operator associated with a centered discrete fractional Fourier transform of power β−α to the image file to produce a modified image; and

determining a change in the mis-focused image and using the change in the mis-focused image in adjusting α for a next iteration,

wherein if values for α between 0 and real number β do not result in a desired outcome, α is adjusted to an imaginary value of the form iχ where χ is the imaginary part of α.