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3.1    NCSA ImageTool


Animation, Palettes, and Plots    3.1

National Center for Supercomputing Applications

January 1991






3.1    NCSA ImageTool


Animation, Palettes, and Plots    3.1




Chapter 3    Animation, Palettes, and Plots



Chapter Overview
Animation
Starting Animation
Animation Controls
Virtual Memory Animation
FTP Options
Connect
Get Loop
Disconnect
Color Palette Support
Color Palettes
Loading Palettes
Modifying Palettes
Saving Modified Palettes
Restoring the Palette
Displaying the Palette
Plots
XY Graphs
Mouse Usage for Making Selections
Contour Plots
3D Plots

Chapter Overview

This chapter covers more advanced display options in NCSA
ImageTool, including animation, palette modification, and plots.


Animation

Animation is an integral part of NCSA ImageTool. The program
uses the information in the text fields of the Control window for
loading animation images, just as it does for individual images.
In most cases, the file specification matches more than one file.

NCSA ImageTool displays the animation sequence at the origin
point of the canvas. If the file specification does not match any
files, the file sizes conflict with the dimensions, or some type of file
error occurs during animation, an error message is displayed in
the Message window.


Starting Animation
Located under the Image menu is the Animate submenu
(Figure 3.1). The submenu contains the default option, Regular
size, and a Zoom (2X) option which initially magnifies individual
frames by a factor of two in each direction.

Figure 3.1    Animate Submenu



NOTE:  Besides selecting animation size from the Animate
submenu, you can also initiate a regular size animation from the
Image text field by pressing CONTROL-A at the end of the file
specification.


Animation Controls
When you select an animation type, five new buttons appear in the
Control window. They are labeled Pause, Last, Next, +, and -. Use
the left button to activate these control buttons.


Pause Button
The Pause toggle temporarily stops the animation. You will want
to pause the animation when you want to perform some other
operation on the images; i.e., magnifying the image, loading an
alternative palette, etc.


Last and Next Buttons
While also in pause mode, you can use the Last and Next buttons to
sequence through images.

+ and - Buttons
The + and - buttons control the animation speed, speeding it up or
slowing it down, respectively.


Cancel
Cancel quits the animation mode.


Virtual Memory Animation
If all of the images for an animation do not fit in the available
physical memory, the images are swapped out to disk until they are
needed. This transfer creates a great deal of network traffic if
your disk is mounted on the network, and a great deal of disk I/O
activity in any case, often causing mouse tracking to slow down. If
this happens, you can click the Pause button, then perform any
necessary action such as slowing down the animation or
canceling the operation.


FTP Options

Further expanding the animation options of NCSA ImageTool is
its built-in network communications capabilities. By using the
FTP (File Transfer Protocol) menu (Figure 3.2), you can connect
to a remote machine and grab images as they are being created.

Figure 3.2    FTP Menu



Connect
Before you can transfer images from a remote machine, you must
establish a connection to the machine generating or containing the
images. To do so:

1.    Select Connect from the FTP menu. A dialog box prompts you for
the name of the host machine.

2.    Enter the name of the host in the text field labeled Host name.

3.    Click the OK button to continue.

Text in the tty window describes the file transfer. The messages
displayed vary from system to system. This is an example of what
you might see in the tty window:

ftp cray
Connected to cray
220-cray FTP Server. Report Problems to [e-mail]
Name (cray:redman):


4.    Enter the appropriate user name for the remote machine at the
Name prompt.

5.    Enter the password, if necessary, and possibly an account or
other necessary codes.

After entering all of the required information, you should see a
message that looks like this:

230 Logged in.


If a message like this does not appear, it may be necessary to re-
enter the user name and password. If this message does appear, the
connection is successful, and you may continue to perform one of
the other operations from this menu. FTP runs in the tty window.
Use the FTP commands available on your machine to change
directories on the remote machine, change options, and so on.


Get Loop
Once the connection is established, you can use the Get loop option.
Get loop transfers the file whenever it becomes available. The
images are displayed in the form of an animation sequence on the
canvas as they are acquired.

Select Get loop from the FTP menu and a dialog box  appears. The
images' filenames are expected to end with a string of digits such
as denap009. This naming scheme is useful for sequencing
animation images.

Specify an increment in the dialog box. This increment is added to
the image filename to create the filename for the subsequent frame
in the sequence. The next field, labeled Interval (sec), specifies the
maximum allowable time to complete the file transfer. FTP times
out if the transfer is not complete in this period of time. If images
are large, you may need to increase this value in order to avoid
timing out in the process of transferring the files. Zoomed image
has two settings: on and off. If it is on, the images are magnified
by a factor of two before being displayed.

The filename in the Image text field of the control panel specifies
the first file to be transferred. The next file to be obtained is
determined automatically by NCSA ImageTool. The numeric
suffix on the original filename is incremental by the amount that
you specified in the Increment field of the dialog box. The name in
the Image field changes to the name of the file presently displayed.

This process continues until you select Stop from the FTP menu.


Disconnect
Select Disconnect from the FTP menu to close the connection with
the host machine. Select Stop to cancel the Get loop option before you
disconnect.


Stop
This option cancels the Get loop operation. In the tty window, a
message is displayed such as:

Get loop stopped


If you do not cancel the Get loop option before disconnecting, NCSA
ImageTool continues to try to receive images, unsuccessfully.


Color Palette Support

NCSA ImageTool supports using, modifying, and creating color
palettes. You can load, change, and save color palettes. For
detailed information on the file format of color palette files, see the
section, "File Formats," in Chapter 2.


Color Palettes

The Sun Workstation can display 256 colors from a palette of over
16 million colors. You can change most of the 256 colors to any one
of the other available colors. Some entries are reserved by the
system and cannot be used by NCSA ImageTool. The first four
entries in the color palette are used for foreground and background
colors, window colors, and text.


Loading Palettes
You can use palette files to initialize your Sun Workstation's
hardware color table. The section, "File Formats," in Chapter 2
describes the file format. To load a new color palette, select Load
from the Palette menu (Figure 3.3).

Figure 3.3    Palette Menu



NCSA ImageTool tries to read colors from the file entered in the
Control window's Palette text field. If the filename does not end in
.pal, the program automatically appends .pal to the filename. If
NCSA ImageTool can't find this file cannot be found, an error
message appears in the Message window. Otherwise, the color
hardware is initialized using the colors from the palette file.

Alternately, to directly load the palette from the Palette text field,
press CTRL-L at the end of the palette filename.


Modifying Palettes
You can alter the currently active palette using NCSA ImageTool's
palette editing capabilities:  Contour, Fiddle, and Transpose.
Selecting either Contour or Fiddle switches to a mode Contour and
to have a special effect. To exit either of these modes, click the right
mouse button.


Contour Mode
Using the contour mode, you can set entries in the palette to white.
To use contour mode:

1.    Select Contour from the Palette menu.

2.    Select a contouring functions by clicking the left or middle
mouse button in the Canvas area.

3.    Depress the left mouse button to set the color under the mouse on
the Canvas to white. Alternatively, move the mouse off of that
point to restore its color.

4.    Release the mouse button to permanently set the color under the
mouse to white.

To use the color initially under the cursor, instead of white:

1.    Hold down CTRL when you press the left mouse button. While
the middle mouse button is pressed, NCSA ImageTool clears
randomly selected colors and leaves others in place. This
creates a contouring effect.


Fiddle Mode
The fiddle mode reduces or expands the range of the spectrum in
the color palette, depending on the mouse location on the Canvas.
To manipulate the palette:

1.    Depress the left button.

2.    Move the mouse toward the top of the Canvas to expand the
spectrum.

3.    Move the mouse toward the bottom of the image to reduce the
range of the spectrum.

4.    Move the fiddle horizontally to shift the spectrum to the right or
left.

5.    Select Transpose from the Palette menu to flip the color palette.
After flipping the palette, the mouse buttons operate normally.

Notice also that while you hold down the middle mouse button you
can rotate the palette in a wrap-around fashion.


Saving Modified Palettes
After altering a palette, you may want to save it for future use by
selecting Save from the Palette menu. A dialog box appears. Use
the text field labeled Palette to enter the name for the new palette
file. Click OK to continue the operation or Cancel to abort.


Restoring the Palette
Use the Restore option in the Palette menu to restore the palette to its
original state. Any modifications that you have made since you
last saved will be lost.


Displaying the Palette
It may help you to display the palette when in this mode so that you
can see the effect of your actions. Use the Show option from the
Palette menu to display a color strip at the origin point on the
Canvas. Once the colors are displayed, you can remove them by
selecting Cut or Clear from the Edit menu.


Plots

In addition to using color to display data, NCSA ImageTool also
provides other plotting capabilities, such as XY graphs, contour,
and 3D plots.


XY Graphs
To create a Cartesian graph:

1.    Choose the XY option from the Graph menu (Figure 3.4).

Figure 3.4    Graph Menu



A new frame and window appear, as well as a dialog box.

2.    Fill in the text field first, then enter the minimum and
maximum horizontal and vertical dimensions into the fields
labeled Xmin, Xmax, Ymin and Ymax.

3.    Enter the minimum and maximum data values for the plot in
the Gmin and Gmax fields.

4.    Click OK to continue or Cancel to abort the operation. If you
select OK, the new window remains on the screen. Otherwise, it
disappears.

If you've selected OK, proceed with the following steps to select a
slice of the image (on the Canvas) that you would like to have
plotted.

5.    Depress the left mouse button while dragging the mouse over a
line of data values you want plotted.

6.    Release the mouse button. A line appears over the area you have
just drawn across (if one doesn't, try clicking the middle mouse
button). If the line is not acceptable, redraw the line by repeating
this process. The previously selected line disappears when you
start to draw a new one. The data values represented by the
colors under the line are used for the plot.

7.    Click the Draw button to plot the points under this line.

Notice the other control buttons in the window. Scale specifies the
values previously entered at the dialog box. Note that the data
range does not have to be in the range 0 to 255, even though the
actual data values displayed fall in this range.

Clear clears the plot window, Print prints the plot on the postscript
printer specified using the Options menu, and Done removes the
window and returns to normal processing. The text field contains
the text that creates the title of the plot.

To produce multiline graphs, draw horizontal or vertical lines
parallel to one another in the image and select Draw after you
select each line.

NOTE:  If NCSA ImageTool does determine that the lines you've
drawn are parallel, the XY plot canvas does not clear to draw the
additional lines; it is drawn over the existing plot.


Mouse Usage for Making
Selections
When making contour or 3D plots, you'll often be making
selections within your images using mouse buttons. The middle
mouse button drags a selection box; clicking outside of this
selection cancels the selection.

If instead of clicking outside the box you press the middle mouse
button inside the box, the cut and paste functions are performed on
the selection, and you can drag the selected area to a new location
on the canvas.

Alternately, holding down CTRL and pressing the middle button
with the mouse inside the selection box performs the copy and paste
operations simultaneously.

Clicking the right mouse button on the canvas undoes the original
selection.


Contour Plots
To create a contour plot:

1.    Select a rectangle from an image to be plotted using the middle
mouse button. (You can also use the middle button to extend your
selection area.)

2.    Select Contour from the Graph menu. A window appears that
displays some buttons and a text field.

3.    Enter the values at which you would like contour lines to be
drawn in the Contour levels text field. You can enter as many or
as few values as you like; the more values you enter, the more
contour lines you'll see.

4.    Click the Draw button. NCSA ImageTool draws the contour plot
in the Canvas area of the plotting window.

To clear this Canvas, click the Clear button. (The image remains
on disk if you have saved it there.)

You can also Print the contour plot to the postscript printer you've
designated using the Set laser printer default item in the
Options menu. If you haven't specified a default laser printer, a
dialog box appears.
Clicking on Done removes the window and returns to normal
processing.


3D Plots
To create a 3D plot:

1.    Select a rectangle that you would like to plot using the middle
mouse button. (You can also use the middle button to extend your
selection area.)

2.    Select the 3D plot option from the Graph menu. A plot window
appears.

3.    Enter the yaw, pitch, and roll values in their respective text
fields. These three elements compose the viewing angle for a 3D
image. Specifically, yaw is the rotation around the x axis, pitch
is the rotation around the x axis, and roll is the rotation about the
z axis. The defaults are 10, 40 and 5, respectively.

4.    Click Draw to plot the selected rectangle. Click Draw again to
change the yaw, pitch, and roll and replot the data.

Pressing the Clear button clears the plot window's Canvas, while
the Print button prints the plot to a postscript printer. Clicking Done
returns NCSA ImageTool to normal operation.