Tk Image Extension rtdimage

At the heart of the RTD software is a Tk image type called rtdimage that was developed as a C++ class hierarchy. Tk has a documented method of adding new image types and the advantage of using it as opposed to developing a new Tk widget is that you can put a Tk image in a canvas window and use all of the canvas graphics functionality to draw over the image. This can be used to display labels and markers on the image or for more complicated star maps overlaying the image.

The rtdimage extension was developed as a C++ class hierarchy and library, which is described in more detail in later sections of this manual. There are classes for implementing Tcl commands, images and widgets, classes for managing the image transformations and display, the colormap and communication with the real-time image server for displaying images from a CCD camera. The functionality of all these C++ classes is available at the Tcl/Tk level as rtdimage subcommands and via a remote control interface. The following subcommands are currently implemented:

rtdimage Subcommand	Description
alloccolors	Allocate or free colors in the colormap.
autocut	Set the cut levels automatically using median filtering or other algorithm.
bitpix	Return data type (BITPIX field) of the FITS image.
camera	Start, stop, pause or continue a CCD camera real-time display.
clear	Clear or blank out the display.
cmap	Load or manipulate a (MIDAS) colormap.
colorramp	Generate an image to use for the colormap display (color bar or ramp).
colorscale	Apply a color scaling algorithm, such as linear or logarithmic scaling to the image.
configure	Set or query configuration options.
convert	Convert X,Y between different coordinate system types.
cut	Set the cut levels directly.
dispheight	Return display height of image (after transformations).
dispwidth	Return display width of image (after transformations).
dump	Dump or save the image as a FITS file.
fits	Access FITS image header information.
flip	Flip the image in the X or Y directions or both.
frameid	return the frame Id (used for rapid frames and rtdServer communication).
get	Return X,Y coordinates and pixel value(s) for a screen position.
graphdist	Plot a graph of the pixel value distribution.
height	Return height of image (before transformations).
isclear	Return true if the image is cleared (no image loaded).
itt	Load or manipulate a (MIDAS) intensity transfer table or ITT.
max	Return maximum image pixel value.
mband	Draw a measure band on the canvas to display the world coordinate distance.
min	Return minimum image pixel value.
mmap	Access the mmap memory in which the FITS image data and header are stored.
object	Return the astronomical object name, if known, for the viewed object.
pan	Support for a panning window.
perftest	Toggle interactive performance testing on or off.
pixtab	Support for displaying a table of image pixel values as the mouse moves.
preview	When a camera is running, stop it and make a local copy of the image.
radecbox	Returns a list of 4 values {ra0 dec0 ra1 dec1} that form an ra,dec box with the given center point and radius.
remote	Start remote control onterface.
rotate	Rotate the image by swapping X and Y coordinates.
scale	Magnify or shrink the image by integer factors.
shm	SysV shared memory access to image header and data.
spectrum	Plot a graph of pixel values along a line in the image.
statistics	Calculate statistics on the section of the image being displayed.
type	Return the type of the raw image data (short, int, float, ...)
update	Update the image.
userfreq	Set the maximum real-time update frequency.
view	Make a view of an image, a second image displaying the same image, possibly at a different magnification and offset.
warp	Warp (move) the mouse pointer in the image.
wcscenter	Return the center of the image in world coordinates.
wcsdist	Return the world coordinate distance between 2 screen pixel points.
wcsequinox	Return the world coordinates equinox of the image.
wcsheight	Return the height of the image in arcmin.
wcsradius	Return the radius (diagonal to center) in arcmin.
wcsset	Set basic world coordinates information.
wcsshift	Shift the world coordinates center of the image.
wcswidth	Return the widthof the image in arcmin.
width	Return width of image (before transformations).
zoom	Support for a zoom window.
zoomview	Support for an alternate implementation of the zoom window using a view of the raw image (now the default)

In addition, the following configuration options are supported for the rtdimage command:

rtdimage option	Description
-displaymode	Sets display mode to 0 or 1 (default 1), see reference manual for details.
-file	Sets (FITS) image file to load and display.
-fitheight	Shrink to fit image in window of this height.
-fitwidth	Shrink to fit image in window of this width.
-newimagecmd	Sets Tcl command to be evaluated whenever a new image is displayed.
-shm_header	If true, put the image (FITS) header in shared memory for access via the remote control interface.
-shm_data	If true, put the image (FITS) data in shared memory for access via the remote control interface.
-subsample	Use subsampling when shrinking images (rather than max value).
-usexsync	Flag: if true, try to use X synchronisation extension of displaying images.
-usexshm	Flag: if true, try to use X shared memory for displaying images.
-verbose	Flag: if true, print diagnostic messages at run time.
-name	Set the name of the image (makes debugging easier)
-min_colors	Set the minimum number of colors to allocate before using a private colormap.
-max_colors	Set the maximum number of colors to allocate.

See rtdimage(n) for more details.