OR A - ORientation search - 2D, uses self-correlation ||

(05/05/08)

PURPOSE

Determines rotational and translational orientation between two images using self-correlation functions.   Example.

SEE ALSO

OR Q [ORientation search - 2D, multireference, rotation & translation, uses self-correlation ||]
AP SH [Alignment - multi-reference, exhaustive rotation & shift ||*]

USAGE

.OPERATION: OR A [rot],[xsh],[ysh],[mir],[cc]
[Find orientation info. This operation can return up to 5 optional register variables:
Variable Example Receives
First [rot] Rotation angle
Second [xsh] X shift
Third [ysh] Y shift
Fourth [mir] [mir] is 1 if mirror necessary
Fifth [cc] Non-normalized cross-correlation coefficient

.EXPERIMENTAL IMAGE FILE: UUU001
[Enter name of the file.]

.REFERENCE IMAGE FILE: GGG002
[Enter the name of the file containing the reference image; dimensions must correspond to those of the first input image.]

.REAL SPACE MASK RADIUS FOR EXP. AND REF. IMAGES: 25,15
[The radii applied in real space to the input and reference images, respectively.]

.RADIUS OF ACF, MAXIMUM SHIFT: 20,5
[Enter the maximum radius of the self-correlation function to be used in angle determination and the maximum shift to be considered.]

.CHECK MIRRORED POSITIONS? (Y/N) : Y
[Check mirrored image when using 1/2 coverage of projection space.]

NOTES

  1. This operation employs the same method as 'AP SH' except it uses self-correlation for determining the angular rotation. For details see:
    Joyeux, L. and P.A. Penczek. Efficiency of 2D alignment methods. Ultramicroscopy, 92, 33-46 (2002).

  2. Implemented by: Paul Penczek

  3. WARNING, the sub-pixel location seems to have a systematic shift error of 0.3 pixel when checked versus known image displacements. al

SUBROUTINES

ORACFMSK, ORACFMSKM, FRNG, CROSRNG_MS, CROSRNG_DS, RTQ_Q, FMRS_2, CCRS_2, FINDMX_Q, FMRS_2R

CALLER

UTIL3