We use the IRAF package developed by Frank Valdes at Kitt Peak IRAF Group
called "color" which enables one to make false-color images of .imh
files which are Sun Raster files.

Then you can use XV or other tools to convert from 24-bit color to 8-bit
color, or save as PostScript and print them.

Below are the details directly from the IRAF package…………

        David E. Wall   w…@donald.phast.umass.edu
        University of Massachusetts, Amherst – Astronomy
        http://donald.phast.umass.edu/
———————————————————————–

PACKAGE (Oct92)                   color                  PACKAGE (Oct92)

           Guide to Making Color Composites from IRAF images

INTRODUCTION

This  guide  describes  techniques  for  taking  three  monochrome  IRAF
images, a "red" image, a "green" image, and a "blue"  image  and  making
color  composites.   There are many techniques which depend on different
hardware and software.  This guide  currently  discusses  three  methods
for  display  on  an  8-bit  color  workstation,  using  Sun  24-bit RGB
rasterfiles, creating a special color map and image  which  samples  the
RGB  color space, and pixel dithering.  The rasterfiles may be displayed
or  printed  using  a  variety  or  non-IRAF  tools  which  are  readily
available  and  which  can be used with 8-bit workstations.  The special
color map and pixel dithering methods  use  only  IRAF  images  and  the
standard  SAOimage/IMTOOL  display  servers  to  display  on 8-bit color
workstation.  These techniques are intended  to  provide  a  rudimentary
color  composite  capability  in  absence  of  better  hardware  such as
IIS/IVAS devices or 24-bit workstations.

For further information on the tasks described here see  the  approriate
help pages.

SUN 24-BIT RGB RASTERFILES

The  task rgbsun takes three input IRAF images and produces a 24-bit Sun
rasterfile.  Though this file type was developed by Sun Microsystems  it
is  a relatively simple format which may useful on other machines having
software designed to use it.  The color image  may  be  display  with  a
variety  of  tools  such  as  xv (a very powerful and generic viewer for
X-window  systems),  xloadimage   (another   X-window   display   tool),
screenload  (a  simple  displayer  on  Sun  computers), and snapshot (an
Open-Look tool).  Also some color printers can be used with this  format
such as a Shinko color printer.

The  recommended  display  tool  is  xv  which  provides a great deal of
capability  in  adjusting  the  color  map  and  size.    This   program
compresses  the  24-bit  colors  to 8-bits on an 8-bit workstation using
color dithering techniques (there  is  a  choice  of  a  slow  and  fast
method).   This  program  also  provides  the  capability  to  write the
picture out to other formats and one may also use screen  capture  tools
such as xwd or snapshot to extract and possibly print the picture.

For hardcopy there is always the option of photographing the workstation
screen.  Different sites may also have color printers which  accept  the
rasterfile  directly  or some other form of capture from the screen.  At
NOAO there is a Shinko color printer which may  be  used  directly  with
the rasterfile to make moderate quality color prints and slides.

24-BIT to 8-BIT COLOR MAP COMPRESSION

The  task  rgbto8  produces  an  8-bit  color map which samples the full
range of RGB color values and an associated image with  values  indexing
the  color  map.   The  compression  algorithm  is called the Median Cut
Algorithm and the image is  dithered  with  this  color  map  using  the
Floyd-Steinberg  algorithm.   The  resulting image is a short image with
199 values.  The color map is output in either  a  format  suitable  for
use  with  SAOimage or with IMTOOL.  This method is recommended over the
pixel dithering method.

The RGB values are input as three IRAF images.  The images must each  be
scaled  to  an 8 bit range.  This is done by specifying a range of input
values to be mapped to the 8 bit range.  In addition the  range  can  be
mapped logarithmically to allow a greater dynamic range.

The  output  image  is displayed with rgbdisplay with either SAOimage or
IMTOOL.  Note that this requires  V1.07  of  SAOimage.   The  color  map
produced  by  the rgbto8 for a particular image must also be loaded into
the display server manually.  With IMTOOL use the setup  panel  and  set
the  file  name  in  the  user1  or  user2  field  and  then  select the
appropriate map.   With  SAOimage  you  select  the  "color"  main  menu
function,  and  then  the  "cmap"  submenu function, and then the "read"
button.  Note that usually a full pathname is required since the  server
is usually started from the login directory.

The  display server must be setup in it’s default contrast mapping (with
IMTOOL you can use the RESET option but with SAOimage you must  restart)
and  the contrast mapping must not be changed.  There are no adjustments
that can be made in IMTOOL but with SAOimage you can adjust  the  colors
using the "gamma" selections and the mouse.

>I’m wondering is anybody has some sort of a program that converts
>IRAF’s images (or FITS images) into GIF, TIFF or whatever XV can
>read. It seems a little bit unusual but I really need it. The point
>is that I’m extracting images from Digital Sky Survey, and this
>STScI’s thing gives me only FITS files. I need to make fancy things
>(like captions, a little editing, etc.) with them and print. That’s
>why I need it.

For presentation-type work, where you only need a qualitative capture
of the image, you can use xv to grab and save any window that is
displayed on the screen, such as in saoimage. It then gives you a few
options for the file format to save it in.

The other option i’m aware of is with Spyglass Transform, which is a
commercial data display program. It can read FITS and save in a
variety of common formats. The drawback, besides the cost (maybe
$300), is that Transform needs a lot of memory to read an image. We
couldn’t get it to read 2k by 2k images with a 24Mbyte sun, but
smaller images work fine.

Hope it helps
Hans-Joerg Deeg

- Hide quoted text — Show quoted text -

Sergei Naoumov <naou…@physics.unc.edu> wrote:
>Hello, folks!

>I’m wondering is anybody has some sort of a program that converts
>IRAF’s images (or FITS images) into GIF, TIFF or whatever XV can
>read. It seems a little bit unusual but I really need it. The point
>is that I’m extracting images from Digital Sky Survey, and this
>STScI’s thing gives me only FITS files. I need to make fancy things
>(like captions, a little editing, etc.) with them and print. That’s
>why I need it.

>I’m sure this problem is not unique, so, please, share your experience
>if you have one.

>Thanks in advance,
>                    Sergei

I usually display the image, then do:

xwd > image.xwd              (make an x window dump)
xwdtopnm image.xwd | pnmtotiff > image.tiff     (converts to a pnm file,
                                                 then to a tiff file)

It’s klunky, but it works. I am open to better suggestions…

"xwdtopnm" and "pnmtotiff" are part of the "pbmplus" package,
by Jeff Poskanzer.

Chris

>naou…@physics.unc.edu (Sergei Naoumov) writes:
>>I’m wondering is anybody has some sort of a program that converts
>>IRAF’s images (or FITS images) into GIF, TIFF or whatever XV can
>>read.
>A disadvantage is that you only get as many levels as your saoimage
>supports – usually it seems to reserve about 200 colors, so this isn’t
>very bad. Using something fancy like pbmplus would give you better
>dynamic range and more control, but would be a lot more work.

>Bruce Macintosh                             b…@astro.ucla.edu

No work at all – use fitstopgm & ppmtogif if you HAVE the pbmplus
package.

But for most applications, as others have pointed out, XV’s screen grab
(which is in versions 3.0 AND 2.0) facility – from an SAOimage display
– will suffice.

—
Karl Glazebrook,           email:  k…@mail.ast.cam.ac.uk
Institute of Astronomy,   finger:  k…@jhereg.ast.cam.ac.uk
Cambridge, U.K.              WWW:  http://cast0.ast.cam.ac.uk/~kgb/

One of the simplest techniques – for producing display images, not
preserving the science data in an image – is just to use xv itself to
grab an image displayed using iraf and saoimage. xv3.00 has a "grab"
button which will grab either an entire window or a portion of it.
Simply use iraf to display the image – which lets you adjust the  levels,
scaling etc. to your liking – in color or greyscale, and then use xv
to grab it, and save it as a gif.

A disadvantage is that you only get as many levels as your saoimage
supports – usually it seems to reserve about 200 colors, so this isn’t
very bad. Using something fancy like pbmplus would give you better
dynamic range and more control, but would be a lot more work.

Bruce Macintosh                         b…@astro.ucla.edu