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When I open my FITS image, all I see is 'white'. Yet everything, including the colorbar seems to work?
However, a number of fits images with this keyword, have invalid values.
Therefor, when DS9 opens the image, it finds no valid data to display. To
correct this problem, either disable DATASEC support, via the Scale menu,
or correct the the value of DATASEC in the fits header. You can also change
the default behavior by disabling DATASEC from the preferences menu.
Grids
When displaying a coordinate grid, the rendered grid is incorrect, or I receive an error message. How can I fix this?
Displaying a valid grid is a complicated process and a lot can go wrong. One of the most common problem is a conflict in defining certain projections in older FITS files. You can tell DS9 to use the old AIPS Projections code by selecting the following menu item 'Edit:Preferences:Misc:Use AIPS Projections'
IRAF
I find that there is a frustrating delay in performing operations on images displayed from IRAF - there's a wait of a second or two before an image is (re)displayed, whereas saoimage reacts virtually instantly for the same type of operation. This makes running imexamine on a batch of images a pain, and using the mouse to change color gamma/bias to desired values basically impossible.
DS9 runs in both 8 bit and 24 bit environments, but saoimage is restricted to 8 bit. If you are running DS9 and saoimage at the same time, then you must be in 8 bit mode. You should not see any delay in changing the color bias/contrast between the two.
However, if you are running DS9 in 24 bit mode, then you will see
slower performance in changing the bias/contrast, as compared to
8 bit mode. Instead of changing a color look up table, as in 8
bit mode, DS9 has to update every pixel on the screen. If your cpu
speed is slow, you can select the Edit:Preferences:True Colorbar
to tell DS9 not to update the entire screen, only a part of the screen.
This should only be needed if your machine is slower than 200 MHz.
Again saoimage does not even run in 24 bit mode, so there
are no comparisons.
I try to display an image from IRAF and I get: ERROR: Cannot open device (node!imtool,,512,512)
DS9 works the same way as ximtool, saoimage, and saotng. No special scripts should be needed. If you have one of the above currently working, DS9 should work 'out of the box'.IRAF can use one of three methods to communicate with DS9: fifo, socket, and unix domain name. The DS9 defaults are:
fifo /dev/imt1
port 5137
unix /tmp/.IMT%d
I try to display an image, I see something, but it's corrupted and I get multiple error messages from DS9...
So when an image server starts (DS9), it will attempt to locate this file as $HOME/.imtoolrc and /usr/local/lib/imtoolrc. If not found, it will look for shell environment variables IMTOOLRC and imtoolrc, that contains the name of the configuration file.
If no configuration file is found, DS9 will assume the following default
configuration:
Another problem is that this file must be in sync with dev$graphcap. If your system administrator has made changes to graphcap, they must also be implemented in imtoolrc.
Here is a note from NOAO:
Where do I find this .imtoolrc file?
Can I display from IRAF to DS9 running under Windows 95/98/ME/NT/2000
Yes, DS9 Windows is also a fully functional IRAF display server. To direct image output from IRAF to DS9 running under windows, use the IMTDEV environment variable. For example, if the windows machine is named 'foo.bar.edu', define IMTDEV to the follow value before entering IRAF.
$ setenv IMTDEV inet:5137:foo.bar.edu
$ cl
cl> display dev$pix
When I display an image from IRAF, the SCALE menu option is not active, Why?
What actually is sent from IRAF to DS9 is one byte per pixel, values 0-200, which already has applied both the upper and lower clipping bounds and the distribution. So this is why, the SCALE menu is disabled in DS9 when it receives a image from IRAF.
Why don't I see PHYSICAL/WCS/WCSA...WCSZ coordinates displayed when I load my image?
Coordinate System | Keyword Values |
WCS / WCSA...WCSZ | CRVAL,CRPIX,CRDELT,CD... (for images) TCRVL,TCRPX,TCDLT,... (for tables) |
Image | none required |
Physical | WCSNAMEP='PHYSICAL' or LTM, LTV |
If the required keywords are not present, values for those coordinates are not displayed.
Note: For PHYSICAL, DS9 will first look for an alternative WCS with WCSNAMEx='PHYSICAL'. If not found, DS9 will then look for the LTMx_x LTVx keywords.
How do I indicate distance on my printed images?
I can make some wonderful color images in DS9 and save them as postscript files that look great, but often when I print them they appear washed out or very different than they do on the screen. My question then is what, if anything, can I do about this?
The problem is that you create an image on a display, which is the product of RGB colors (red, green, and blue) and print the image on a printer, which is the product of CMYK colors (cyan, yellow, magenta, and black). Furthermore, every monitor is different in how it will display a certain color, and every printing technology is different in how well it will reproduce that color. And finally, the translation between RGB and CMYK is not symmetric, i.e. its not possible to translate some colors back and forth.
It's possible to calibrate your monitor and your printer, to create a translation matrix, to correct for problems outlined above (in the Macintosh world, this is what ColorSync does). The idea is to apply a gamma correction to the output of DS9, so that it will print much more in line with what you expect. To do this you'd need special software and hardware, and its only valid for your monitor and your printer.
In summary, its not worth it. Especially in the case of publication, such as ApJ, where you have no idea on what printing technology will be used to reproduce your image. So the only control you have is to calibrate your monitor and to hope for the best.
However, there are some rules of thumb that might help. First, printers have a very hard time with blues and purples, as they tend to be washed out. Either avoid these colors, or over compensate these colors. Second, when printing from DS9 for publication, choose CMYK as opposed to RGB in the print dialog box.
ApJ has a good idea in that you send in both an electronic version and a hard copy of your color image. That way, they can manually adjust the printers to try to match your output.
Guidelines for Authors Submitting Electronic Art Files
9. Figures that are intended to be printed in color must be prepared as CMYK
(i.e., four-color) files, not RGB files. (RGB files cannot be used for printing
10. When preparing grayscale figures, use gray levels between 20% and 80%, with
at least 20% difference between the levels of gray. Use a screen of 80 lpi or
lower (coarser) and make the figures as close to final publication size as
possible, as reduction can cause levels of gray to drop out. Whenever possible,
use different patterns of hatching instead of grays to differentiate between
areas of a figure.P.S. Even though ApJ recommends 300 dpi, I believe this is over-kill. For 3 or 4 color separated images, 150 dpi is plenty of resolution and 1/4 the file size.
When I start DS9, I get the following error message:
When I run ds9 with the tvtwm window manager, sometimes the open file dialog box does not appear?
If you are running tvtwm, and you are currently viewing a virtual screen other than the first, when you open a file, the dialog box will appear in the first virtual screen, not your current. This is a bug with tvtwm and not ds9.
I have a laptop, that most of the time, is connected to a network. DS9 runs fine. However, when I'm not connected to a network and I start DS9, it hangs. What's going on?
The following is from the XPA documentation:
Determines the socket connection method used by this session of XPA. The choices are: inet (to use INET or Internet-based sockets) and local (unix) (to use UNIX sockets). The default is INET. Using the inet method will allow access from other machines (subject to access controls) but using local will not. Local is most useful for private access and when the machine in question is not connected to the Internet
More information is available on XPA shell variables at: The XPA Environment
I have Red Hat 7, and I'm running KDE. The magnifier keeps going blank after a few seconds, what's going on?
I have FreeBSD. When I run ds9, I get the following error: ELF binary type "0" not known Whats going on?
The solution was to use the brandelf utility on the file to ensure that the machine understood that it was a linux program.
% brandelf -t Linux (filename)
I have Windows 98. All line graphics, such as regions and contours appear corrupted. What's going on?
How to I configure windows to automatically start ds9 when I double click on a fits file?
The following instructions are for Windows 2000. The procedure for other versions of windows should be similar. First, ds9 needs to be installed in the C:\Program Files\ds9 directory (this is the default location).
Next click on the Startup button, and select the Settings menu item. Now select the Control Panel menu item. Next, double click on Folder Options. This will bring up a dialog box. Click once on the File Types tab.
Now click once on the New button. Enter FITS and click on the OK button. Now click once on the Change button. Select ds9 from the list, and click the OK button. Finally, click once on the Close button. All done. Now, when you double click on any file with an extension of FITS will open within DS9.
Everytime I create an auxiliary window in ds9, such as a Pixel Table, or Analysis Plot, it will retreat behind the main ds9 window. Then, when I bring the auxiliary window to the front and move the mouse out of it, it automatically goes behind the main ds9 window again. What can I do to fix things so that the auxiliary window stays on top of the ds9 window?
To fix things so that the auxiliary window stays on top of the ds9
window, do the following:
I am unable to configure ds9 as a "helper application" for viewing FITS files in Netscape or Mozilla. Is this possible?
Yes, it is easy to configure Netscape or Mozilla to automatically
invoke ds9, when downloading a fits file. These instructions are for Netscape
4.x. Other versions follow a similar process: From the Edit menu,
select Preferences. In the dialog box, click once on the arrow
next to Navigator, and then Applications. Click
once on New button and enter the following information:
Description | FITS |
MIME Type | image |
Suffixes | fits,fits.gz |
Application | ds9 %s |