RB 3F - Rotate, Shift, Back Projection in Fourier space |

(1/10/07)

PURPOSE

Changes the scale, rotates, and shifts image circularly. Then calculates 3D reconstruction using interpolation in Fourier space.Rotates counter-clockwise around the center (NX/2 + 1, NY/2 + 1). Negative angles = clockwise. This operation is the same as 'RT SQ' followed by 'BP 3F'.   Example.

SEE ALSO

RT SQ [Rotate and Shift - image, Quadratic interpolation ||]
BP 3F [Back Projection - 3D, Interpolated in Fourier space ||*]
RB 32F [Rotate, Shift, Sampled, Back Projection in Fourier space |]

USAGE

.OPERATION: RB 3F

.TEMPLATE FOR IMAGE FILES (E.G. STK@****): INSTACK03@
[Enter template for the names of the file(s) to be rotated. This template can alternatively refer to a series of single images (e.g. img***), or to a series of stacked images (e.g stack3@***), or to a whole stack of images ending in '@' (e.g. stk@). Templates containing an asterisk will have the astericks substituted with a number for the file.]

If the template contains an asterisk the following question will appear:

.FILE NUMBERS OR SELECTION DOC. FILE NAME: 1-700 OR IMAGE_SEL
[Enter projection file numbers or the name of the document file containing projection file numbers in the first column.]

.ANGLES DOC FILE: ANGLES27
[Enter the name of the document file containing Eulerian angles for the projections used (psi, theta, phi).]

.SYMMETRIES DOC FILE: symmetries
[Enter the name of the document file containing Eulerian angles defining symmetries (psi, theta, phi). The angles should be such that when used in operation 'RT 3D' transform the volume into itself. The identity operation (angles 0,0,0) MUST be included.
The symmetries are enforced in two steps: projections related by the symmetry operations are added in Fourier space to the volume; in order to reduce the residual artifacts, additional real-space symmetrization is applied.
If there are no symmetries, enter symbol "*".]

.TRANSFORMED OUTPUT IMAGES TEMPLATE (E.G. ROT@****)',
[Enter template for the names of the rotated and shifted output image files. This template can alternatively refer to a series of single images (e.g. img***), or to a series of stacked images (e.g stack3@***), or to a whole stack of images ending in '@' (e.g. stk@). Templates containing an asterisk will have the astericks substituted with a number for the file. However a single asterick will skip any output for these images.]

If this output template contains an asterick the following question appears:

.FILE NUMBERS OR SELECTION DOC. FILE NAME: select_03
[Enter the file numbers to be substituted into the output file name template or name of a selection document file that contains the file numbers in the first register.]

The following questions always appear:

.RECONSTRUCTED VOLUME: VOLUME001
[Name for the backprojected output volume calculated using all input projections specified in the selection document file.]

NOTES

  1. A change of scale will not change the image dimensions. All the parameters agree with the output of the marker program (operation 'MK').

  2. The input file may be three-dimensional. In this case, each of the slices is separately rotated and shifted with respect to the z-axis, and stored in the output file, which will be created with the same dimensions.

  3. Shifts can be any real numbers.

  4. The accuracy of interpolation is much higher than that of the bilinear interpolation used in the 'RT' operation, but it is lower than the accuracy of bi-spline interpolation. In particular, the derivatives of the interpolated image are not continuous. The speed, however, is much higher than bi-spline interpolation.

  5. Since quadratic interpolation is used, it is possible for the output image minimum & maximum intensities to be outside the range of those in the input image.

  6. 5x5x5 Kaiser-Bessel interpolation scheme is used.

  7. This operation is NOT parallelized for use with MPI.

  8. Implemented by Paul Penczek and ArDean Leith.

SUBROUTINES

BP3F, ROTQSS, RTSQ, QUADRI, GETDOCDAT

CALLER

VTIL2

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