AIPS HELP file for DOALIGN in 31DEC18
As of Mon Jan 22 15:09:37 2018
Type: Adverb (Logical)
Use: Controls how two or more maps are aligned by various
tasks. If DOALIGN positive (actually >= 0.1), then the
images are aligned by their coordinates and are required
to have the same axis increments, types, and rotations.
If DOALIGN is zero (actually -0.1 < DOALIGN < 0.1), then
the images are aligned by their coordinates at the bottom
left corner (computed linearly without regard for
rotation), but no other tests are made. If DOALIGN is -1
(actually <= -0.1 and >= -1.5), then the images are
aligned by offset from their reference pixels and no axis
parameter tests are made. If DOALIGN = -2 (actually <
-1.5), the images are aligned at pixel (1,1,...) and the
headers are ignored --- which can lead to bad output
headers of course.
Null value: true (1).
BLANK.......Blanks regions of an image using the TV or another
BLSUM.......Sums images over irregular regions.
COMB........Combine two images in various ways.
CORMS.......Combine two images in various ways with error
GREYS.......Grey-scale plot with overlayed contours.
PCNTR.......Contour plot with overlayed polarization vectors.