NAME

imregister - register an image using objects in a reference image

USAGE

imregister input output refimage [coords] [cntrbox] [srchbox] [niterate] [refrecen] [execute] [interpol] [boundary] [geometry] [z1] [z2] [verbose] [logfile]

PARAMETERS

input = ""

Image to register.

output = ""

Registered output image.

refimage = ""

Reference image.

coords = ".coo"

Reference object coordinates file. This file need not yet exist. If the specified name starts with a period, it is assumed to be an extension to the reference image root name.

cntrbox = 7

Size of the fine centering box in pixels.

srchbox = 11

Size of the coarser search/centering box in pixels.

refrecen = no

Recenter the reference coordinates? Only set this parameter to 'yes' when the reference coordinate file does not yet exist, or when 'refrecen' was inadvertently set to 'no' when it was generated.

execute = yes

Perform the image transformation? If not, then the task will output a file named "geomap.sol" containing the derived transformation, but will not perform that transformation. This may be useful as a dummy run of this task, or when only generating the reference coordinates file.

interpol = "spline3" ["nearest"|"linear"|"poly3"|"poly5"|"sinc"]

Type of interpolation to use.

boundary = "wrap" ["nearest"|"reflect"]

Type of image boundary handling to use.

geometry = "rscale" ["shift"|"xyscale"|"rotate"|"rxyscale"|"general"]

Type of geometric model to fit. All options, except "general" fit linear geometric transformations; "general" also attempts to fit a non-linear polynomial distortion.

z1, z2 = INDEF

Lower and upper cut levels to use when displaying both input and reference image. Default INDEF will be appropriate for most users.

verbose = yes

Print center, shift, magnification and rotation?

logfile = "register.log"

Name of the text log file.

DESCRIPTION

Task to register (i.e., shift, (de)magnify and rotate) an image using a list of matched input coordinates. The coordinate file need not yet exist or even be specified; if absent, the reference image is displayed and the user may interactively mark reference objects. Then the image that is to be registered to the reference image is displayed with the numbered positions of the reference objects indicated. If the only transformation required is a translation, then the user need only mark the position of the first of the reference objects in the image that is to be registered, and the remaining objects will be found automatically; if there is also a magnification and/or rotation, then all objects need to be marked in the same order that the reference ones were marked, unless the magnification and/or rotation are so slight that all objects are still within the search box ('srchbox') from their location in the reference coordinates file and no other object move into that search box.

If a very large transformation is required, one may want to start with marking only a few reference objects that can easilly be identified in the image to be registered. And subsequently use more objects to perform the final registration during a second call to this task. If a transposition is involved you may want to transpose the image first, such that the image orientation is closer to that of the reference image.

Note, that interpolation of pixel values always leads to a slight loss in spatial resolution, and in a change of the noise characteristics of the images (correlated noise).

EXAMPLES

Register an image to a reference image:

    rj> imregister 0152.NGC5267U 0152.NGC5267Ur 0137.NGC5267U "" refrecen+
    IMREGISTER: input     = "0152.NGC5267U.fits"
                reference = "0137.NGC5267U.fits"
    Wait for the cursor cross to appear in the image display area, then
    mark at least 3 objects (stars) for coordinate referencing using
    the 'c' key (press q to quit).
        ...
        (mark stars)
        ...
    Recentering objects in the reference coordinate list ...
    Wait for the cursor cross to appear in the image display area, then
    mark all reference stars in the same order using the 'c' key.
        ...
        (mark one or more stars, depending on the situation)
        ...
    Guessing the positions of the unmarked reference objects...
    Recentering objects in the coordinate list ...
    GEOMAP:  Computing the spatial transformation function...
        X fit ok.  Y fit ok.
        Xin and Yin fit rms: 0.06708224  0.0366997
        Mean Xref and Yref: 321.5475  289.5375
        Mean Xin and Yin: 320.9775  289.715
        X and Y shift: -0.6733525  0.5605336  (xin  yin)
        X and Y scale: 0.9995855  0.9995855  (xin / xref  yin / yref)
        X and Y axis rotation: 0.047  0.047  (degrees  degrees)
    GEOTRAN: 0152.NGC5267U.fits --> 0152.NGC5267Ug.fits
    Finished.

and text log file 'register.log' will list the following information:

    IMREGISTER:  IRAF2.12.1  raj@hasnap  Dec 10 22:37:49 2003
        reference = 0137.NGC5267U.fits
        refcoords = 0137.NGC5267U.coo
        input     = 0152.NGC5267U.fits
    TVMARK:  N_obj = 5,  N_marked = 1,  N_guessed = 4
    GEOMAP:  Computing the spatial transformation function...
        X fit ok.  Y fit ok.
        Xin and Yin fit rms: 0.06708224  0.0366997
        Mean Xref and Yref: 321.5475  289.5375
        Mean Xin and Yin: 320.9775  289.715
        X and Y shift: -0.6733525  0.5605336  (xin  yin)
        X and Y scale: 0.9995855  0.9995855  (xin / xref  yin / yref)
        X and Y axis rotation: 0.047  0.047  (degrees  degrees)
    GEOTRAN: interpol  = spline3   boundary=wrap
        0152.NGC5267U.fits --> 0152.NGC5267Ug.fits
    IMREGISTER: Finished.

REVISIONS

IMREGISTER v2.11, Jun 19 2000 [R.A. Jansen]

First 'rjtools' version of this task, building on an earlier script by RAJ; IRAF 2.11.3

IMREGISTER v2.12, Jul 12 2003 [RAJ]

Changed 'imroot'->'impath//imroot' after change to 'chkimg'; IRAF 2.12.1

IMREGISTER v2.12, Jul 29 2003 [RAJ]

Changed 'cparse'->'ocparse' after revamp of task 'cparse'; IRAF 2.12.1

IMREGISTER v2.12, Aug 24 2004 [RAJ]

Wrote this help file; IRAF 2.12.2

IMREGISTER v2.12, May 26 2007 [RAJ]

Added 'geometry' parameter (see manual of 'geomap' for the meaning of the available choices). 'rscale' used to be hardcoded and remains the default. Also added cut level parameters 'z1' and 'z2'. Default values INDEF ensure meaningful cut levels in most cases, and allow input and reference image to have different signal levels; IRAF 2.12.2

IMREGISTER v2.12, May 28 2007 [RAJ]

Updated this help file; IRAF 2.12.2

BUGS

SEE ALSO

tvmark, geomap, geotrans, chkimg, ctrcoo, xdisplay, ocparse