Image mosaicking

mosaic is a routine which will take a list of images (infiles) and their associated confidence maps (confmaps) and will create a output tile based on the on-board WCS solutions in the input file headers. Simple or multi-extension fits files can be specified, but the structure of an image file and its associated confidence map file must match exactly. The file list can be specified as a comma delimited list or in a text file (one file per line). If the latter is being used, then an '@' symbol followed by the file name will be the signal that the images are listed in a text file. The output tile is written to outfile and the associated confidence map will be written to outconf.

At present there are not many ways in which the user can control the output tiles. The centring, rotation and scale of the output map is worked out entirely automatically. The user can choose whether to use nearest neighbour or bi-linear interpolation when mapping the input images onto the output grid. It is also possible to some degree to specify how the output background is worked out and even to specify a pedestal level.

ARGUMENTS

infiles: Input files separated by comma or a file list as an @list.
confmaps: Respective confidence maps for each of the input files. These can also be specified either by a comma delimited list or as an @list
outfile: Output stacked image. The output will be in the form of a simple FITS file.
outconf: Output confidence map. This will also be in the form of a simple FITS file.

OPTIONS

The following options are supported. Default values are specified after the equal sign.

--interp=1: The interpolation method to be used -- the following integer values are allowed:
0: (nearest neighbour) An input pixel is mapped to the location on the output grid that is nearest to its equatorial position
1: (bi-linear interpolation) An input pixel is divided up into the four pixels on the output grid that surround the input equatorial position. The fraction going into each output pixel depends on the amount of overlap of the input pixel.

--skyflag=2: A flag to determine how the final sky is to be worked out -- the following integer values are allowed:
0: Don't do anything. Just use the backgrounds as they are in the input files.
1: Set the sky background in the final image to a value given in the --skywish_in option.
2:Set the sky background to the mean of the backgrounds for the input images.
--expkey=EXPTIME: Name of the keyword which stores the exposure time.
--skywish_in=0: If the option --skyflag == 1, then this is the value that you want to set for the sky background.
--conflim=25: Any pixels with a confidence value lower than this will be ignored.
--(no)verbose (no): If set then some verbose output will be generated