chimgtyp HEADAS help file

NAME

chimgtyp - Converts (changes) the data type (BITPIX) of an image array of the FITS image extension.

USAGE

        chimgtyp infile outfile datatype

DESCRIPTION

CHIMGTYP converts the data type of the image extension. It writes the image array to an output file with modified bitpix value and modified array values as requested by user. The FITS defined data types are:

      ----------------------------------------------
      datatype   meaning                    bitpix
      ----------------------------------------------
      UBYTE       8-bit unsigned byte          8
      USHORT      unsigned short              16
      SHORT       signed short                16
      ULONG       unsigned long               32 
      LONG        signed long                 32
      FLOAT       single precision float     -32
      DOUBLE      double precision float     -64

CAUTION

Note that certain convertions (e.g., float --> int, double --> float, long --> short, etc.) may cause loss of information.

PARAMETERS

infile [string]

The name of the input image file.

outfile [string]

The name of output file.

datatype[string]

Datatype to be converted to (e.g., USHORT, or LONG, etc.).

(Fnull= -1e37)[float]

Value to assign undefined floating point pixels for output file. This is used when datatype is FLOAT or DOUBLE.

(Inull= -99)[int]

Value to assign undefined integer pixels for output file. This is used when datatype is LONG, or SHORT. Possible limits of this value, for converting to various datatypes are:

        datatype            limits
        -------------------------------------
        UBYTE                  0 to 255
        USHORT                 0 to 65535 
        SHORT             -32768 to +32767
        ULONG                  0 to 4294967295
        LONG         -2147483648 to 2147483647
        -------------------------------------

(copyall= yes)[boolean]

To copy all other existing extensions from the input file. By default, it is set to value 1 (true) which means, the task will copy all other existing extensions from the input to output. To reverse this option, one needs to enter copyall=0 in the command line.

(clobber = no) [boolean])

Flag specifying whether or not a pre-existing file with the same name as that requested as the output file from this task will be overwritten.

EXAMPLES

1. To convert image type from DOUBLE to ULONG,

     prompt> chimgtyp infile outfile datatype=ULONG Inull=99

BUGS

None Known

LOG OF SIGNIFICANT CHANGES

V1.0.0 (1997 August)

PRIMARY AUTHOR

Banashree M Seifert

CONTACT FOR PROBLEM

http://heasarc.gsfc.nasa.gov/cgi-bin/ftoolshelp