Splitting a single image into multiple sections

If each observation initially exists as a single image but needs to be treated as multiple images because different regions have been read out using different electronics (so that, for instance, they have to be debiassed using different ADC factors), then a slightly different approach is required. In this case, you should set MODE=SPLIT, and unlike for the other modes MAKESET will create new NDFs each with its own Set header. You will have to supply the parameter OUT to give the name of the file containing the split data: this will be a single HDS container file containing as many NDF structures as the input array is split into. For full generality, the parameter SECTIONS specifies how the input image is to be split up, but for the common case of dividing the array into grid of rectangles which butt up to each other the XSTART and YSTART parameters are easier. The following example shows creation of a Set made by dividing a 2048x4096 array into quarters:

% makeset in=sg28948 mode=split out='*_sp' \
          sections='!' xstart='[1,1025]' ystart='[1,2049]'

    MAKESET
    =======
  1 NDF accessed using parameter IN

 Set name  Set index   NDF name                            CCD_SET domain
 --------  ---------   --------                            --------------

 Writing to container file sg28948_sp
 sg28948:
               1       sg28948(1:1025,1:2049)              PIXEL
               2       sg28948(1:1025,2049:)               PIXEL
               3       sg28948(1025:,1:2049)               PIXEL
               4       sg28948(1025:,2049:)                PIXEL

The command creates a single new HDS container file ``sg28948_sp'': when you give this as an input to CCDPACK commands they will look inside and process each of the four images in turn.

This method could also be used to create a Set from different slices of a three-dimensional data set.