The VD data output by *CROSS-CORR* are an essential component for
NEWSIPS processing. The information it carries is used as input to the
photometric correction scheme to align properly the raw science image to
the raw-space ITF image (
Chapter 6) and by the geometric correction
scheme as one of the vector components to the geometric resampling stage
(Chapter 7).
These specific data, however, are not retained directly in
an IUE Final Archive output data product. As is discussed in
Chapter 7
, the VD FITS file (VDLO/VDHI) produced during the geometric
correction procedure contains the summation of all the geometric
corrections implemented to perform the single image resampling. The raw
cross-correlation information can be retrieved indirectly from the
binary table extension to the VDLO/VDHI. *CROSS-CORR* does not
generate any flag values.

The *CROSS-CORR* module writes the following information to the
HISTORY portion of the image label:

- window size,
- template size,
- ITF identification,
- percent successful correlations,
- median cross-correlation coefficient,
- standard deviation of the cross-correlation coefficient,
- mean computed displacement in pixels,
- maximum computed displacement in pixels, and
- number of isolated or semi-isolated displacements filtered.