Vista User's Guide
Vista Display

Many of the data taking programs used at Lick Observatory use Vista to display the data. The Vista Display is mostly self-explanatory, however some commands are not obvious. This guide should help both first time and experienced users become more familiar with the program.

When Vista is started by the data taking programs it brings up two windows, the image display window (Figure 1) and the image control window (Figure 2), as shown below.

These windows can also be started from Vista directly by typing xtv.

Image Display Window

Figure 1: Vista image display window

The image display window simply shows the image and the image name as recorded in the FITS header. As you move the cursor around the image, the cursor pixel position and value are displayed in the upper left corner of the image control window. Vista puts the origin (0,0 pixel position) at the upper left hand corner. While the cursor is in the image display window you can do the following functions:

Middle Mouse Button: Brings up a help window listing the functions below.

Left Mouse Button: Image in the 'Zoom window' of the Image Control Window will be updated.

Right Mouse Button: Similar to left mouse button, but the image is also redisplayed so that the pixel which was directly under the cursor is now positioned at the center of the display window. This is useful because the magnify buttons on the Control Window always magnify about the center of the display window.

Arrow Keys: Move cursor in the image window.

B or b: Allows you to draw a box on the image using the mouse. Follow the instructions which appear in a new window on the screen. The box limits the area in which a row or column plot will be plotted, if the cursor is within the box when R or C is pressed.

C or c: Produces a new window with a column plot of the image at the location of the cursor.

R or r: Produces a new window row plot of the image at the location of the cursor.

Z or z: Does a 'Zap' median filter at the location of the cursor. Serveral 'Zap' parameters can be modified via commands on the ITV popup menu from the Vista control window.

Image Control Window

Figure 2: Vista image control window

The image control window allows you to manipulate the displayed image in a number of ways, including color map and zooming. Clicking the middle mouse button in the different regions of this window brings up an appropriate help window.

Image cursor position (row and column) and value are displayed in the upper left hand corner of the control window.

A small zoomed image is displayed in the top left center round region. This is updated by pressing the left (or right) mouse button in the image display window.

The top right center square region denotes the image display window area (black outlined region) with the image area (green outlined region). You can move the image around the display region by clicking (with the left or right mouse button) on the part of the green outlined image you want centered on the display.

The oval buttons on the right of the control window control the zoom factor of the image display window (from 1/8 to 8 times zooming). The other oval buttons (clip, fine, and lock) allow you to control the color map:

Clip: Prevents wrapping of the color map.
Fine: Allows fine adjustment of the color range using the mapping bar to the immediate left.
Lock: Locks the current color map and prevents autoscaling when displaying a new image.

The color bar at the farthest right shows the current color map. In the color bar, moving the mouse up or down while holding down the left or right button, will allow you to "roll" the color map up or down.

At the center of the control window is a histogram of the pixel values in the image. Above the histogram is a solid bar showing the range of values the color bar (at the right of the window) covers. Below the histogram is the range of values the histogram covers (top numbers) and the range of values the color bar covers (bottom numbers). The range of values for the color bar can be manipulated with the mouse. To do so, put the cursor on the solid bar above the histogram. The cursor should change into either an arrow pointing up, or an arrow pointing to the upper left or right. By holding down the left or right mouse button, you can move the entire color bar (straight up arrow) or change its length (upper left or right pointing arrow). When you release the mouse button, the image will be redisplayed with the new color map.

The X-lations menu allows you to chose either Linear, Square Root (Sqrt), or a Logarithmic (Log) color scale.

The Color Ctrl menu allows you to choose other color tables (Other...), Invert the current color map, switch to a Black and White (B & W) color table, or switch to a Contour map.

The Options menu has a number of additional choices for examining the displayed image. The menu options (Itv..., Digitals..., and New Image...) will be discussed in more detail later. The other options are:

Show Label: Toggle switch to display file name and FITS header object name on image display.
LWPrint: Print full image in grayscale using color parameters set with the control window. This usually makes a very large file and is not the recommended way of printing images.
LWP [Box]: Print only the image within the box (defined by using B or b in the image display window). This produces smaller files and is the recommended way of printing your image from Vista.

Itv Menu

Figure 3: Interactive TV Menu

Vista Box: 1 (or any number 1 to 20). This can save box parameters for the display window. Pick a box number and then use B to set the box in the image display window.

Delete Current Box. Does just what it says.

Recenter Image. This will redisplay the image with the center of the image at the center of the display window.

Display Whole Image. This will zoom (or unzoom) the image so the entire image is displayed in the display window.

Filter Size: 15r 15c. This both tells you the current size of the median filter box as well as lets you change it to whatever values you wish.

Threshold 4.0. Both tells you the current threshold used in median filtering as well as allowing you to change it.

Pick Stellar Stat Loc. Allows you to pick a position on the image for doing stellar statistics. To do this simply click (with left mouse button) on Pick Stellar Stat Loc then click on the desired point on the image.

Do Stats. Brings up the Statistics Window for the position marked by Pick Stellar Stat Loc.

Add to Focus Data. Allows you to input a focus number (whatever is applicable for the telescope/instrument you are using) and it will be saved with the stellar statistics you just measured. This can be repeated for stars for different images and focus values. All inputed focus points points and data are fitted by a parabola to give the best focus position.

Erase Focus Data. Erase all focus data currently in buffer.

Sky/Stats Box: 21r X 21c. Both shows current sky/stats box size and allows you to change size of box over which sky statistics are calculated.

Statistics Window

Figure 4: Statistics Display

This window displays statistics for the star or region designated by the Pick Stellar Stat Loc option on the Itv menu. The following data is calculated for the region within the box (as set by Itv Sky/Stats Box): sky level, peak value, centroid, sigma, eccentricity, position angle, total counts, and total counts minus sky.

The bottom box shows a plot of the focus data and the best fit parabola (when there are 3 or more data points) with an estimate of the best focus position. Focus data is added using Itv Add to Focus Data option. A status bar above that box gives the fitting status (e.g. No data to fit yet! or Need 1 more point.)

Digitals Window

Figure 5: Digitals Display

After clicking on Digitals... with the left mouse button, the computer waits for you to click on the point of interest in the image display window. The window shown in Figure 5 will then be displayed showing the pixel values for that point and a few rows and columns around it. The data may be saved to a file for later recall using the Print to file button. You may also elect to read previously saved data from a file using the Select file option.

Clicking on another point in the image will update the digitals display for that new point. You may also click on a pixel value in the digitals window to center around that point.

New Image Menu

Figure 6: New Image Display Menu

This menu allows you to display FITS images stored on disk. The default directory is the data directory for the instrument you are using (the /data directory). If New Image is not seeing that directory, you can get there by clicking on datadir. The other easily accessed directory is the Vista directory (by clicking on vistadir). If you want to access a different directory, use the other... button and input the full path to the directory you want.

Selection=*.ccd. Shows what files are being selected and allows you to change the default extension, e.g. *.fits will show any filenames ending with .fits, *.* will show every file in the chosen directory.

Count = Last 10 .... Allows you to chose how many files are displayed as options for loading. The default is the last 10 files written to disk. Entering 0 shows all files, -N shows last N files written, N shows first N files written.

long. Shows long description of image (i.e. file name, image size, date written, object name).

short. Shows just the file names to choose from.

The box right of the "short" button shows the path name for the files listed (in Figure 6 above the path is /data/).

Get new image list. Once all the above parameters are set, then click here to update the image list.

Status: Gives a status message (e.g. 10 image names, Displaying, etc.).

The bottom large window lists the files available for displaying. Figure 6 above shows that there are currently no *.ccd images in the /data/ directory for displaying. If there are images to display, just click on the image name to display it.

Last modified: Tue Apr 6 15:07:19 PDT 1999 by
Elinor Gates