---
name: "rtd"
section: "1"
platform: "linux"
package: "skycat"
version: "3.1.2+starlink1~b+dfsg-9"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/rtd"
---

# rtd(1)

real-time image display application

## NAME

rtd - real-time image display application

## SYNOPSIS

**rtd** *options filename*

## DESCRIPTION

The rtd application is used to display FITS images in real-time. The application is based on "rtdimage", a Tk image extension for displaying FITS images.

## OPTIONS

- **-file name**

  "name" specifies a FITS format file to load and display.

- **-subsample bool**

  If bool is true, subsampling is used when shrinking the image, i.e.: if the image is shrunk by 1/3, only every third pixel is displayed. Otherwise, the maximum value is taken from the group of pixels.

- **-sampmethod n** (experimental)

  If option 'subsample' is false, the following methods can be used for displaying a shrunk image (i.e. an image with a scale factor \< 1):

- 0

  max value of all pixels in a NxN box (default)

- 1

  min value of all pixels in a NxN box

- 2

  mean value of all pixels in a NxN box

- 3

  median value of all pixels in a NxN box

- 4

  max value of pixels on a diagonal cross in a NxN box

- 5

  min value of pixels on a diagonal cross in a NxN box

- 6

  mean value of pixels on a diagonal cross in a NxN box

- 7

  median value of pixels on a diagonal cross in a NxN box

- 8

  median value of pixels in a chess-board like box

- 9

  median value of a 3x3 box

- **-usexshm bool**

  If bool is true (default), attempt to use X shared memory for the image display, if available. This improves performance considerably, but is only available when working on the system console.

- **-usexsync bool**

  If true, try to use X synchronisation.

- **-verbose bool**

  If bool is true, diagnostic messages are printed out to show what is going on internally (for debugging use).

- **-default\_cmap**

  This option sets the default colormap file to use when starting up.  Only the root of the filename should be specified for this option, for example: "ramp" for a grey level colormap.  For a list of available colormap files, see the colormaps directory in the rtd release.

- **-min\_colors n**

  - **-max\_colors n**

  Specify the min and max number of colors to allocate before using a private colormap.

- **-default\_itt**

  **This option is similar to -default\_cmap, except it** **sets the default ITT (intensity transfer table) file** **to use at startup.  ITT files are also stored in the** **colormaps directory.**

- **-xscale xs**

  - **-yscale ys**

  Set the default scaling factors (default: 1).

- **-camera name**

  Set the camera name for real-time image events: default: taken from the RTD\_CAMERA environment variable, if set, otherwise set to RTDSIMULATOR, for simulation test mode.

- **-zoom\_factor number**

  Set the scale factor for the zoom window (default 5 x the original image).

- **-colorramp\_height h**

  Set the height of the colorramp subwindow (default: 20).

- **-with\_zoom\_window bool**

  If bool is true (default), add a zoom window.

- **-with\_pan\_window bool**

  If bool is true (default), add a panning window.

- **-dozoom bool**

  If true, turn on zoom window.

- **-disp\_image\_icon bool**

  If true, display a copy (view) of the image as an icon.

- **-drag\_scroll bool**

  If true, set bindings to scroll with the middle mouse button.

- **-scrollbars bool**

  If true, display scrollbars to scroll the image.

- **-port port**

   Default port for remote connections (0 means system chooses a\
    port).

- **-debug bool**

   Debugging flag: enables real-time simulation with testProg\
    (below).

- **-testprog path**

  For testing: name of test program used to generate real-time updates (tRtd).

- **-interval n**

  For testing: interval between updates in ms.

- **-with\_perftest bool**

  If true, display performance tester utility in menu bar.

- **-with\_warp bool**

  Option to warp the mouse pointer.

## FILES

$RTD\_LIBRARY/../demos/rtd.tcl

## SEE ALSO

[rtdServer(1)](/rtdServer/1.md),RtdClient(1),RtdCubeDisplay(1),[skycat(1)](/skycat/1.md)