rtextimage: Convert text files to IRAF images

Package: dataio

Usage

rtextimage input output

Parameters

input: A list of text files containing image pixels and optional header. Most likely the output from rcardimage, see examples below.

output: The output IRAF image name. If more than one text file is being read, the ordinal of the text file in input is appended to output to generate a unique image name.

otype = "": The data type of the output IRAF image pixels. If left unset and the IRAFTYPE keyword is found in the FITS header, output pixels will be of type IRAFTYPE. If IRAFTYPE appears more than once in the FITS header, the last value of IRAFTYPE is used. If left unset and the IRAFTYPE keyword is not provided in the FITS header, the output data type is determined from the pixels themselves.

header = yes: If header = yes, rtextimage will attempt to read a FITS header at the beginning of each text file.

pixels = yes: Read the pixel values from the input text file. If no then the output image is initialized to zero pixel values.

nskip = 0: The number of lines to skip before reading pixels. This is used to skip over a non-standard header and is important only when header = no.

dim = "": A string listing the dimension of each axis. The number of dimensions listed equals the number of image dimensions. This information must be entered unless it can be read from a FITS header.

Description

Text files are converted to IRAF images files with procedure rtextimage. The text file consists of an optional header optionally followed by the pixel values. If no pixel values are read the image is initialized to all zero pixel values. If pixel values a given they are read in FITS order, that is, the leftmost subscript varies most rapidly. The number of image dimensions and the length of each dimension must either be read from a FITS header or supplied by the user. Internally, rtextimage determines the format (integer or floating point) of the pixels in the text file by reading the first one and assuming all others are the same.

Examples

1. Read a file written by wtextimage from the magtape file "mta[1]" into the IRAF image "picture".

cl>  rcard mta[1] | rtext out=picture

2. Read a series of text files with no headers preceding the pixels. The text files were previously read from tape with task rcardimage. The two dimensional images are 512 by 320 pixels, and will be named crab001, crab002, crab003, etc.

cl> rtext text.* crab header- dim=512,320

3. Read a file with a non-standard header. The header is 5 cardimages long.

cl> rcard mta[5] | rtext out=spect.1 head- nskip=5 dim=1024

Time requirements

Task rtextimage requires about 145 cpu seconds to write a 512 square image (integer or real) from a text file.

Bugs

The text file being read cannot have lines longer than SZ_LINE characters (see hlib$iraf.h).