- Form: MERGE im1 im2 im3 im4 ... [NOMATCH]
-
- im1
- is the first buffer to be used in the average,
and is also the destination buffer,
- im2, im3, ...
- are the other images to be used in the average,
- NOMATCH
- allows the merging of images whose pixels do not
line-up exactly.
MERGE will merge between 2 and 20 images or spectra into one image or
spectrum, with the pixels in the overlapping regions being replaced with
the average. Merging is done in relative coordinate space (or "world"
coordinates). The FITS cards CDELT1 and CDELT2 are checked to make sure that
all of the images are on the same scale/pixel (to within +/- 0.01 pixels
across the range of an image). If this condition is met the images are
then checked to make sure that the starting coordinates are an integral
number of pixels away from each other (again to within 0.01 pixels). If
the NOMATCH keyword is used then this last check is not performed and any
given pixel is added to the closest adjacent pixel in the "master" image.
(This uses the NINT function in FORTRAN, and allows the user to avoid
unnecessary interpolations in some cases.)