CDAT comes with a script (found in the bin directory of your cdat installation) called spktovcs.py

You can either use it from the command line:

spk2scr.py --help

usage: spk2scr.py [options]

    Reads in and converts Ferret (spk) colormap file to vcs colormap
    If method is set to 'blend':
      colors will be set using the ferret % value, and blending will be used in between
      0% in ferret corresponds to index_start
      100% in ferret corresponds to index_end
    If method is set to 'contiguous':
      colors will be set starting at index_start and assigned in order as found in the ferret (spk) file,
      no blending between colors


options:
  --version             show program's version number and exit
  -h, --help            show this help message and exit
  --file=FILE           Ferret (spk) colormap file to convert, [default:
                        pal1.spk]
  --name=NAME           Name of the returned vcs colormap, [default: uses
                        ferret (spk) file name]
  --out=OUT             Name of the returned vcs script file, [default:
                        file.scr]
  --index_start=INDEX_START
                        start index for mapping of ferret colors into vcs
                        colormap, [default: 16]
  --index_end=INDEX_END
                        end index for mapping of ferret colors into vcs
                        colormap, [default: 239]
  --method=METHOD       method for mapping of ferret colors into vcs colormap
                        (blend or contiguous), [default: blend]
  --blend               end index for mapping of ferret colors into vcs
                        colormap, overrides --method option
  --contiguous          end index for mapping of ferret colors into vcs
                        colormap, overrides --method option
  --verbose             Enable verbose method while converting colorcells,
                        [default: False]

>>> import spk2scr
>>> print spk2scr.spk2vcs.__doc__

    Reads in and converts Ferret (spk) colormap file to vcs colormap
    If method is set to 'blend':
      colors will be set using the ferret % value, and blending will be used in between
      0% in ferret corresponds to index_start
      100% in ferret corresponds to index_end
    If method is set to 'contiguous':
      colors will be set starting at index_start and assigned in order as found in the ferret (spk) file,
      no blending between colors

    Usage:
    cmap, ncolors = spk2vcs(file,cname=None,x=None)
    Input:
    file                     : Ferret (spk) colormap file
    cname                    : VCS output colormap name, if None, uses ferret file name
    x                        : vcs canvas, if None then a vcs canvas instance will be created
    index_start              : 0% of ferret % index, default is 16
    index_end                : 100% of ferret % index, defalut is 239
    method                   : 'blend' or 'adjacent', defalut is 'blend'
    Output:
    cmap                     : vcs colormap object, with conitguous color set from index_Start if method='contiguous'
                               or spread from index_start to index_end if method is 'blend'