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PLANETARY DATA SYSTEM
USER'S GUIDE FOR THE PDS IMDISP PROGRAM
INTRODUCTION
This document describes the IMDISP program, an interactive
image display utility for the IBM Personal Computer family (PC,
XT and AT) and compatibles. It has been developed for use with
the Compact Disk - Read-Only Memory (CDROM) storage systems
currently being evaluated by the Planetary Data System (PDS). It
can also be used to display images stored on floppy or hard
disks.
This User's Guide presents an overview of image processing
and CDROM fundamentals, a section on the installation of IMDISP
and CDROM software and hardware, a description of IMDISP program
operation, a description of other utility programs which can be
used in conjunction with IMDISP, and a command summary.
Other support software for using the PDS CDROM disks has
also been developed. These packages include the USGS Planetary
Image Cartography System (PICS) for Microvax computers, a set of
FORTRAN routines to access CDROM disks on VAX computers (VMSCD),
and "C" language source code to process disks written in the High
Sierra format. Contact Mike Martin (JPLPDS::MMARTIN) for access
to these tools.
Chapter 2
BACKGROUND
Efforts to utilize small computer systems for display and
analysis of scientific data have been hampered by the lack of
sufficient data storage capacity to accommodate large image
arrays. Most planetary images require nearly a megabyte of
storage. Over the past two years a new storage technology "CDROM"
has been developed which provides the capability to store up to
600 megabytes of data on a single 4.72-inch disk. The disks can
be mass produced, and hundreds of copies of large digital
archives distributed rather than the few sets currently produced.
Readers for CDROM disks can now be purchased for under a thousand
dollars for use on personal computers and some science
workstations.
The PDS has worked with industry and other government
agencies to support the development of CDROM as a major data
distribution and storage media for space science data. Initial
development efforts by the PDS, the Voyager Project, and multi-
disciplinary science representatives have resulted in the
production of 5 CDROM disks, two samplers, and 3 disks containing
all 6,538 images from the Voyager Uranus encounter. The IMDISP
program can be used to display most of these data files on a
personal computer equipped with a CDROM drive.
2.1 DIGITAL IMAGE PROCESSING SUMMARY
A digital image is a picture converted to numerical form so
that it can be stored and used in a computer. The image is
divided into a matrix of small regions called picture elements,
or pixels. The rows and columns of pixels are called "lines" and
"samples", respectively. Each pixel has a numerical value, or DN
(data number) value, quantifying the darkness or brightness of
the image at that spot. In total, each pixel has an address (line
number, sample number) and a DN value, which is all that the
computer needs for processing. The DN value of each pixel usually
represents a shade of darkness or brightness between black and
white (gray levels). How many gray levels there are in an image
depends on the number of bits used to represent each pixel
intensity in the computer. The number of gray levels will be
equal to 2^n, where n is the number of bits per pixel's DN value.
If 8 bits are used to represent a pixel's DN value (gray level),
the system will be capable of using 2^8, or 256, gray levels in
an image, where DN 0 is pure black, and DN 255 is pure white. If
each DN used only 4 bits of storage, the image would contain only
2^4 or 16 gray levels; if there were only 1 bit per DN, the image
would contain only black and white pixels (bit values of 0 or 1).
2.2 OVERVIEW OF IMDISP CAPABILITIES
While the specifics of IMDISP commands are discussed in
Chapter 4, this section provides a general overview of how a user
can manipulate images once a file is selected. There are DISPLAY
commands which allow the user to display all or part of an image
at various positions on the display screen. The user may also
zoom in and out from a point on the image defined by the cursor,
and may pan around the image. The cursor may be turned on or off;
when on, the arrow keys are used to move the cursor around the
screen; when off, the cursor is not visible.
A user may choose to "subsample" the image, to enable more
or all of the original image to be displayed on the screen at
once. For example, if the image were subsampled by a factor of 2,
every other pixel from every other line would be displayed,
starting from the upper left corner of the image. If a factor of
3 were chosen, every third pixel from every third line would be
displayed. Any positive integer may be used for subsampling.
The user may produce a histogram of an image file, which is
a graph showing the number of pixels per DN value, or per range
of DN values, for the entire image. Histograms are overlaid on
top of the image, but may be removed using the REFRESH command.
Subsampling may be specified when computing a histogram to reduce
the time required for the calculations.
A profile may be created which plots DN value versus pixel
along a line between two points on the image. After the cursor is
used to select the two endpoints, the connecting line is drawn on
the image and the profile is plotted at the bottom of the screen.
The user may also "stretch" the image, which is analogous to
turning the contrast knob on a TV set. The user specifies low and
high DN values; all pixels with values lower than the specified
"low" become black, and all pixels higher than the specified
"high" value become white. All pixels between the low and high
values are evenly shaded between black and white.
There are bookkeeping types of commands, also. These allow
the user to do such things as retrieve a desired image from the
CD-ROM, to save an image to a file on hard disk, and to erase
only the graphics from the screen or to erase the entire screen.
Users may execute batch command files to do a series of tasks
automatically. Lastly, the user may, of course, EXIT the IMDISP
program when done.
2.3 GRAY LEVEL AND FALSE COLOR IMAGES
Most planetary images are composed of 8-bit DN values
representing monochrome brightness levels in the scene. To obtain
color images, separate images are taken through color filters
(red, green, blue) and are then combined by ground processing
systems to produce a true color image. Only a very small fraction
of planetary images are available in color versions. Most display
and analysis is done on monochrome images.
A display with 256 (2^8) gray levels is required to present
the information contained in a standard image. However, the human
eye can only distinguish about 32 gray levels. Thus 5-bit DN
values would satisfy most display requirements. Unfortunately,
computers are oriented to the storage of and manipulation of
items which are a power of two, and 5-bit pixels would be very
clumsy. The display devices which the IMDISP program supports are
limited to 16 gray levels (PGA), 4 gray levels (EGA) or 2 gray
levels (CGA). The 16 gray levels of the PGA are adequate to
support image analysis; however 4 or 2 gray levels are
practically useless for viewing planetary images. Fortunately the
EGA display will support 16 different colors, and a color palette
can be selected which uses a graduated scale of colors to
represent gray levels, producing a "false color" image (false
because the displayed color does not represent the actual color
of the scene).
A false color image (also called a pseudo color image) is
created from a black and white image by assigning a color (rather
than a gray level) to each DN value in the image. For instance, a
DN value of 128 could be reassigned to yellow if the user so
desired. Ranges of DNs (e.g., 100-125) may also be assigned one
color. Pseudo colors get assigned to DN values in a pseudo color
table, which the display program then uses to determine how to
color the image on the monitor. Display programs often have
preset pseudo color tables with commonly used DN-color
combinations, and the user can simply call for one of these when
generating a pseudo color image. The option exists, of course,
for users to generate their own pseudo color tables. Pseudo
colors are often used to highlight features of an unusual nature
in an image.
Since the Enhanced Graphic Adapter for the IBM PC provides
only 4 gray shades (black, dark gray, light gray and white) most
image viewing is done using a pseudo color table which interprets
gray levels as color values ranging from black through reds,
greens and blues up to white.
2.4 RADIOMETRIC AND GEOMETRIC CORRECTIONS
All camera systems have some kind of distortions in the
lens, in the way the shutter works, etc. Distortions in the
amount of fight transferred through the camera to the imaging
plate are called radiometric distortions. Geometric distortion
affects the "squareness" of an image, and is detected by taking
an image of a geometric grid.
For spacecraft cameras, both types of distortion can be
measured before launch, and in a limited fashion, in flight.
These measured distortions are saved in digital files. When a raw
image is received, these "calibration files," as they are called,
are subtracted from (or otherwise applied to) the image,
effectively removing radiometric and geometric distortion. This
process is called radiometric and geometric correction. Corrected
images contain the closest possible representation of the scene
being imaged.
2.5 IMAGE FILE FORMATS
Digital image files are seldom stored as a simple array of
pixels. Generally there is an area at the beginning of an image
file containing descriptive information about the image. This is
referred to as a label or header area. Figure 2-1 shows a diagram
of a simple image format with a label area followed by the image
lines. In practice, images from planetary missions have a more
complicated format, due to the need to store additional
information to allow proper interpretation of the image data.
Figure 2-2 shows the format of a Voyager image, which has
engineering parameters embedded at the end of each image line to
form a line suffix area, an engineering trailer record after the
last image line, and this is followed by an image histogram.
--------------------------
| Labels or Header Area |
|--------------------------|
| Image Array Line 1 |
|--------------------------|
| Image Array Line 2 |
|--------------------------|
.
.
.
--------------------------
| Image Array Line n |
--------------------------
Figure 2-1: Simple Image Format
Different image label formats have been developed for use by
nearly all image processing facilities. Two formats are widely
used within the planetary and astronomy communities: the VICAR2
(Video Image Communication and Retrieval) labels used by the
Multi-Mission Image Processing Laboratory (MIPL) and FITS
(Flexible Image Transport) labels used for astronomy image
interchange. The PDS has developed a label scheme which is very
similar to these standards, called the Object Description
Language (ODL). This format attempts to add a broader range of
data descriptive capabilities to the proven capabilities of the
existing label systems. A description of the ODL architecture is
given in Appendix D.
Most of the images stored on the PDS CDROM disks have either
ODL or VICAR2 labels. IMDISP will automatically interpret these
labels to determine the display format of the image data.
--------------------------------------
| PDS ODL Labels |
|--------------------------------------|
| Image Array Line 1 | Line Suffix |
|--------------------------------------|
| Image Array Line 2 | Line Suffix |
|--------------------------------------|
.
.
.
---------------------------------------
| Image Array Line 800 | Line Suffix |
|--------------------------------------|
| Image Engineering Trailer |
|--------------------------------------|
| Image Histogram |
--------------------------------------
Figure 2-2: Voyager CDROM Image Format
2.6 CDROM FUNDAMENTALS
(note: this short section has been deleted to save file space
when transmitting the sample 1000 X 1000 digital orthophoto. CD-
ROM doesn't directly related to that sample)
Chapter 3
IMDISP INSTALLATION
IMDISP requires an IBM PC, XT, AT or 100 percent compatible
with 512K of base memory. It supports several graphics display
devices, including the Enhanced Graphics Adapter (EGA), the
Video Graphics Array (VGA), the Professional Graphics Adapter
(PGA), and the Color Graphics Adapter (CGA). The hardware
environment in which the program has been developed and tested
includes and AT class computer, deluxe or enhanced EGA board
with 256K of memory, and multisync or multiscan monitor.
3.1 PROGRAM SETUP
The IMDISP program can be run from a floppy or hard disk. To
use the program from a floppy disk, insert the program disk in
the A: or B: drive and type the MSDOS command: "A:" or "B:" to
set the floppy disk as the default drive. To use the program from
hard disk first create a directory to hold the IMDISP files. Use
the MSDOS command "MKDIR \IMDISP" to create a directory to hold
the programs. Use the "CHDIR \IMDISP" command to make IMDISP the
default directory. Insert the distribution floppy disk in floppy
disk drive A:. Now type "COPY A:*.*" to copy the files from the
distribution disk to your hard disk. You should now be able to
run all examples from that directory on your hard disk. If you
wish to use IMDISP from other directories, you need to include
the IMDISP directory in your MSDOS "PATH" command. This command
provides MSDOS with a list of directories to search when looking
for a program file to run. If you wish to run IMDISP from
different directories, the \IMDISP subdirectory should be added
to the PATH command in your AUTOEXEC.BAT file. A sample path
command would look like this:
PATH=C:\DOS;C:\UTIL;C:\WORDSTAR;C:\IMDISP
The sample batch files and special pointer label files
included on the distribution disk will only run if your current
default directory is \IMDISP.
You may want to add a line to your AUTOEXEC.BAT file which
will allow you to abort the display program while running batch
files or displaying large image files. If the command "BREAK=ON"
is placed in CONFIG.SYS, you will (sometimes) be able to
terminate the IMDISP program by typing the control and break keys
simultaneously. Different computer systems offer varying response
to the control-break command, and the use of this command may
effect other programs you use.
3.2 CDROM SETUP
(This section also deleted; see section 2.6 above)
3.3 DISPLAY DEVICE CHARACTERISTICS
IMDISP automatically finds out which display devices are
available (PGA, EGA, or CGA) and uses the one available. The
Enhanced Graphics Adapter must have at least 128K of memory to
work properly. Use of the Color Graphics Adapter is discouraged
because the pixels have no gray levels, only black or white.
The display coordinates start at (1,1) in the upper left
corner of the screen; the line direction is down and the sample
direction is to the right.
3.3.1 Enhanced Graphics Adapter (EGA)
The EGA is a bit-mapped display device providing a
resolution of 350 lines by 640 samples of 4-bits each. It
produces a digital video signal for each primary color (red,
green and blue), The video signal for each color can be set to
one of four levels, roughly equivalent to off, low, medium and
high. Thus the number of possible colors (color palette) is 64
(4^3). The following table illustrates the colors created by some
of the different combinations of red, green and blue.
Red= off, Green= off, Blue= off results in Black
Red= low, Green= off, Blue= off results in Dark Red
Red=medium, Green= off, Blue= off results in Light Red
Red= high, Green= off, Blue= off results in Bright Red
Red= low, Green= low, Blue= low results in Dark Gray
Red=medium, Green= low, Blue= off results in Brown
Red=medium, Green=medium, Blue= off results in Yellow
Red=medium, Green=medium, Blue=medium results in Light Gray
Red= high, Green= low, Blue= off results in Orange
Red= high, Green= high, Blue= high results in White
Table 3-1: Sample EGA Color Palette Settings
The EGA display is limited to only 16 colors out of the 64
possible, because only 4-bits are used to store each pixel value
in memory. This 4-bit pixel value points to an entry in the color
table which represents one of the 64 possible combinations of
red, green and blue which can be displayed.
Many of the newer EGA boards are capable of displaying
additional lines and samples when using a Multisync or Multiscan
monitor. The standard EGA uses a 16 Mhz crystal oscillator
(something like a clock which regulates the display speed), which
limits the video output rate to the equivalent of 640 pixels by
350 lines. The EGA circuitry allows for a faster crystal
oscillator to be added to the board (24 Mhz and beyond) allowing
about 25 percent more lines to be displayed (480 lines instead of
350). A method for adding this capability to an existing EGA
board (for about $10 worth of parts) is described in the
September 16, 1986 issue of PC Magazine.
This mode requires that a multisync or multiscan monitor be
attached to the computer, and there is no way for the program to
automatically detect the presence of the special monitor.
Therefore this display mode is invoked by specifying an MSDOS
"ENVIRONMENT" variable. This is done by issuing an MSDOS "SET"
command at the MSDOS prompt as follows:
SET IMDISP=EGA480
This command can also be put in your AUTOEXEC.BAT file using
a text editor, so that you need not invoke it each time you run
IMDISP. It should have no effect on other MSDOS system
operations. There is a chance that adding this variable will
exceed the size reserved by MSDOS for environment variables. If
so, you should consult your MSDOS manual to increase the
environment size on your system. The environment variable can be
removed with the MSDOS command:
SET IMDISP=
Where a carriage return is typed immediately after the equal
sign. The 480 line mode requires an additional 83K of memory for
the refresh buffer. If you try this mode and receive the message
"Insufficient memory for line buffer", it is probably because you
have a 512K memory machine, or have memory resident programs
operating (like Sidekick or Superkey) which reduce the available
memory to less than about 400K. You will need to use the 350 line
mode or remove some memory resident programs to operate in 480
line mode.
Users of the EGA with Multisync and Multiscan monitors can
achieve a 16 gray level display through the use of a special
device called the Grayscaler EP, from Avocado Computer, Box 1655,
Wheaton, Md., 20915, (301) 593-5586. This cable converts the
digital video signals produced by the EGA board to analog
signals. By selecting appropriate EGA palette entries, a fairly
good representation of 16 gray levels can be achieved (use the
palette selection "PAL LOAD GRAY16.PAL" to select this palette).
3.3.2 Video Graphics Array (VGA)
This version (4.0) of the IMDISP program includes support for the
IBM Video Graphics Array (VGA) display device. The VGA produces
an analog display with several new color modes. Of particular
interest to IMDISP users are the 640 x 480 line mode with 16
displayable colors (or gray levels). The 320 x 200 line mode
with 256 displayable colors (or 64 gray levels) has been tested
but produces very blocky pixels. This version of IMDISP supports
the 640 x 480 mode.
To set the VGA display mode you must set a MSDOS environment
variable prior to executing IMDISP.
To set the environment variable use the MSDOS command:
SET IMDISP=VGA
This will put the display in 640 sample by 480 line mode, with 16
gray levels or colors displayable from a palette of 256K. The
display is initialized with a gray scale palette, but a
pseudocolor palette can be invoked with the IMDISP command "PAL
PS 0". The "PALETTE EDIT" command will allow you to step forward
or backward through the 64 available shades for each primary
color. See the next section of the IMDISP manual for more
information on the palette edit function.
Users who wish to experiment with the 320 x 200 VGA mode may use
SET IMDISP=VGA320
but be warned that all text messages expect an 80 column screen,
and therefore wrap-around on the display creating a mess. This
mode is only provided for experimentation and is not for casual
users!!!
3.3.3 Professional Graphics Adapter (PGA)
The PGA is a special graphics board developed by IBM for use
with CAD/CAM applications on the IBM PC. Because its architecture
is incompatible with the CGA and EGA boards, it has not been well
received by software developers. The PGA provides an analog video
signal with a display resolution of 480 lines by 640 samples of
8-bits each. It provides 16 intensities for each primary color,
resulting in a palette of 4,096 colors (16^3). The color table
allows 256 colors to be displayed simultaneously, however only 16
gray levels can be selected.
Use the command:
SET IMDISP=PGA
at the MSDOS prompt to force IMDISP to go into PGA display mode.
3.3.4 Color Graphics Adapter (CGA)
The CGA display is a bit-mapped graphics device with a
resolution of 200 lines by 640 samples of 1-bit each. It supports
only 2 colors in this display mode, black and white. This display
can be used to get a general idea of the contents of a digital
image, or for displaying one bit images (graphics for example)
but is not recommended for use with the PDS CDROM images.
To force a multi-function display card into CGA mode, use:
SET IMDISP=CGA
Chapter 4
IMDISP OPERATION
IMDISP can be used to display images up to several thousand
lines and samples with a variety of pixel formats. These formats
include bit (1 bit), nibble (4 bits), byte (8 bits), or integer
(16 bits). Integer pixels are assumed to be byte-swapped, which
means that the sign and most significant 7 bits are in the
rightmost byte, and the least significant 8 bits are in the
leftmost byte. This is the convention used by both the IBM PC and
VAX computer hardware families. IBM mainframes and 68000 series
computers (Macintosh and Sun, for example) use un-byte-swapped
integers.
Program interaction with the user is via commands typed in
response to the "COMMAND:" prompt. Most interaction is performed
on the graphic display screen, and program messages are printed
over any image display currently on the screen. The REFRESH
command can be used to restore an image after other commands have
written text over the display. The ERASE command can be used to
clear away the clutter left by program status messages and
previously displayed images. The screen is not automatically
erased after each operation in order that multiple images can be
displayed simultaneously, or so a histogram can be placed on the
screen with the image.
IMDISP is invoked by typing "IMDISP" or "IMDISP filename",
where filename is the name of an image file to be opened for
processing at program start-up. The filename may include a disk
drive and path name specification.
The program will blank the display screen and display a
welcome logo, then the prompt "COMMAND:" will appear in the lower
left portion of the screen. If a filename is included in the
command invocation, the welcome message is not displayed and the
screen will display the COMMAND: prompt.
Typing "HELP" at the command prompt will provide a list of
IMDISP commands. The most frequently used commands are "FILE" to
open a file for processing, and "DISPLAY" to display an image
once the file has been opened.
4.1 COMMAND SYNTAX
The command line syntax is of the form:
COMMAND KEYWORD1 = VALUE1 KEYWORD2=VALUE2 KEYWORD3 VALUE3 .
. .
The command line may be typed in either upper or lower case.
The command and the keyword names may be abbreviated to 3
characters in most cases. Any number of spaces may be inserted
between words, and the keyword and value may be separated by a
space or an equals sign. Some keywords do not require a value.
All keywords are optional and have default values.
4.2 COMMAND DESCRIPTION
Table 4-1 presents a summary of IMDISP commands. They are
separated into 3 groups, file manipulation commands; display
commands and program control commands. Only the capitalized
letters are required to specify a command.
4.3 OPERATING MODES
Several of the commands invoke special program operating
modes. These include the FILE command when issued without a
filename argument and the CURSOR, PROFILE and PALETTE EDIT
commands. The FILE mode displays a list of files in the current
directory on the screen for selection. It also contains several
subcommands for controlling the display of files on the menu
screen. In the CURSOR, PROFILE and PALETTE EDIT commands the
cursor keys (arrow keys) on the numeric keypad are used in
conjunction with other keys to control program operation. These
modes are exited by typing either a period '.' or carriage
return.
File oriented commands:
CD . . . . to change the default directory
DIRECTORY . . . . to perform the MSDOS directory
command
FILE . . . . to specify the name of the image
SAVE . . . . to save the image display to a file
TYPE . . . . to perform the MSDOS type command
LABEL . . . . to display the image labels
Display commands:
BROWSE . . . . to display a group of images
DISPLAY . . . . to display the image
ERASE . . . . to erase the display
OVERLAY . . . . to place an overlay on the image
REFRESH . . . . to refresh the image plane
PALETTE . . . . to adjust the palette for the
display
HISTOGRAM . . . . to display the histogram of the
image
SET . . . . to set DN value range
STRETCH . . . . to do a linear gray scale stretch
CURSOR . . . . to move the cursor around
PROFILE . . . . to plot a profile of the image
TEXT . . . . to draw text on the image
Program control commands:
BATCH . . . . to execute a batch command file
MENU . . . . to select images from a menu file
EXIT or QUIT . . . . to exit from the program
HELP . . . . display help information
SYSTEM . . . . execute MSDOS commands
Table 4-1: IMDISP Command Summary
4.4 ERROR HANDLING
If an invalid command is issued at the COMMAND: prompt the
program will beep and return to the COMMAND: prompt. In handling
command parameters the program takes action on those parameters
that are recognized, but ignores invalid parameters. For example,
issuing a "SET LO = 25 HI = 100" command will not have any effect
since the proper parameter names for the SET command are "DNLO"
and "DNHI".
It is also possible for certain system errors to be
encountered which cause the program to abort leaving your
computer in graphics mode. N you are using certain utilities
which reset the default text mode screen colors (like the Norton
Utilities screen attributes command) you may not be able to see
what is being printed on the screen. The simplest approach is to
perform a warm boot, by typing the Ctrl, Alt, Del keys
simultaneously. Alternately, you can often type IMDISP then EXIT
to reset the computer to text mode. Errors in processing image
files on CDROM, hard disk or floppy disks can cause these aborts.
4.5 COMMAND REFERENCE
This section lists all IMDISP commands alphabetically and
describes their function, parameters which control command
operation, and provides examples of command use, In the command
and parameter description the following conventions are used:
filename represents the name of an MSDOS file, and may include
an optional drive identifier and path specification.
n represents an integer value.
4.5.1 BATCH
The BATCH command reads commands from the specified batch
command file. If no file name is specified the current directory
is searched for a file named BATCH.CMD. The CURSOR, PROFILE and
PALETTE EDIT commands should not be used within batch command
files since they require interactive inputs from the keyboard.
The BATCH command may take the following argument:
filename filename of batch command file.
A batch file is simply a text file containing a list of
commands, with each command terminated by a carriage return. If
the command file is created with a word processor, the program
should be used in the non-document mode, to assure that carriage
returns are embedded between command lines. An example of
creating a batch file to display the PDS logo image follows.
At the MSDOS command level type:
COPY CON TEST.CMD
FILE LOGO.IMG
DISP ZOOM 4
DISP ZOOM 2
DISP
DISP SUB 2
EXIT
Now run IMDISP and type"BATCH TEST.CMD" at the "COMMAND:"
prompt. Make sure the file "LOGO.IMG" is in your current
directory. The PDS logo should be displayed on the screen in
several different sizes.
4.5.3 BROWSE
The BROWSE command will display all images in a directory
one after another. An optional directory mask can be supplied to
display only selected files ("BROWSE *.IMG"). The command creates
a list of files to be displayed, then creates and executes a
batch command file to display those images. After each image is
displayed, the filename is displayed at the top of the image. A
BROWSE session can be interrupted by pressing control-s, then
restarted by pressing control-q TWICE. A session can be halted by
typing any other key during the display. It can then be restarted
(from the beginning) with the command "BROWSE C:BATCH.CMD". The
default file name for the batch file created by the BROWSE
command is 'C:BATCH.CMD'. This name can be changed using the
"SET BROWSE fname" command where fname can consist of a drive
letter and filename, which should be terminated with the
extension ".CMD".
The BROWSE command has one argument and several optional keywords.
fname optional file selection mask (must immediately
follow the command BROWSE). May include a drive
letter but not a subdirectory name. Examples (*.img,
L:*.BRS).
SIZe n allows the display of multiple images on the
screen. For example, on a 640 x 480 VGA display,
six 200 x 200 images can be displayed adjacent to
each other.
SUBsample n used in conjunction with the SIZE command, to
scale each image to fit in the SIZE specification.
NOLabel inhibits writing the file name label at the top of
each image as it is displayed.
As an example, the command "BROWSE *.* SIZE 200 SUBSAMPLE 4" will
display all the files in the current directory, subsampling each
by 4 and displaying them in a 200 x 200 window. The command
"BROWSE *.BRS SIZE 100 SUB 2" when used with the Voyager Uranus
browse images (on Volume 3 of the Uranus CDROM collection) will
display up to 24 images at a time on the screen.
*** NOTE ***
BROWSE does not distinguish between image and non-image files,
and it is up to the user to provide the appropriate directory
mask to select ONLY images. If a message "Image does not have
proper label" comes up on the screen during BROWSE, it is
probably because a non-image file is in the directory you are
browsing. You can type carriage returns several times to get
back to the "COMMAND:" prompt, and the browse will continue.
If you are using BROWSE on a computer without a hard disk, you
will have to use the SET BROWSE command to change the default
browse file name to a writable disk drive, for example:
"SET BROWSE A:BROWSE.CMD". If you are using BROWSE to view files
on a CDROM disk, be sure to include the drive letter of a
writable disk drive if you specify a BROWSE file name. The
BROWSE command file produced by the BROWSE command can be edited
with a text editor to produce your own custom command files.
4.5.3 CD or CHDIR
The CD or CHDIR command is used just as it is at the MSDOS
command level to change the current default directory.
The argument of the CD command is the path name
specification of the new default directory. For example, "CD
\IMDISP\IMAGES" would make \IMDISP\IMAGES the current directory
if it exists. To change the current default drive use the
"SYSTEM" command ("SYSTEM L:" for example) or the "FILE"
command. If there is not enough memory available for the system
command to be executed an error message is displayed.
4.5.4 CURSOR
The CURSOR command is used to select a point in a displayed
image for subsequent display commands. When first invoked, it
places a small cursor symbol at the center of the screen.
Depending on the current contents of the screen, the cursor may
be hard to see. Moving it with the arrow keys on the numeric
keypad will help you locate it.
Whenever the cursor is moved, the current line and sample
location of the cursor and the DN value of the pixel at that
point is printed in the lower right portion of the screen. The
cursor will move 16 pixels in the selected direction unless the
movement value is adjusted using the + or keys.
Numeric Keypad Keys
-------------------------------
| 7 | 8 | 9 | PrtSc |
| Home | Up | PgUp | |
-------------------------------
| 4 | 5 | 6 | - |
| Left | | Right | |
-------------------------------
| 1 | 2 | 3 | + |
| End | Down | PgDn | |
-------------------------------
Action of Keypad Keys:
7 = Move up and left.
8 = Move up.
9 = Move up and right.
4 = Move left.
5 = Not active.
6 = Move right.
1 = Move down and left.
2 = Move down.
3 = Move down and right.
- = Decrement cursor movement value.
+ = Increment cursor movement value.
Table 4-2: IMDISP Cursor Keys
Cursor mode is exited by typing a "." (period) or carriage
return. The cursor position is retained for future use in DISPLAY
commands which use the CENTER option. It is very useful with
large images where the entire image may be displayed using the
subsample option, then a point selected for subsequent display at
full resolution.
Example: Type "FILE MONTAGE.IMG" followed by "DISP" to
display the MONTAGE.IMG file. Type "CUR" to enter the cursor
mode, then move the cursor to the center of the Uranus image in
the upper left corner of the image using the up and left arrow
keys. Now type "." to exit cursor mode, then type "DISP ZOOM 4
CENTER" which will display Uranus as a large grainy ball on the
screen.
4.5.5 DIR
The DIR command is used just as the MSDOS dir command. Its
argument is passed to MSDOS for execution. At the end of the
directory listing the screen will display "Type carriage return
to continue:" which will return to the IMDISP command mode. If
there is not enough memory available for the system command to be
executed an error message is displayed.
4.5.6 DISPLAY
The DISPLAY command reads an image file and displays it on
the the screen. If the image is larger than the display screen,
the default mode is to display as much of the upper left portion
of the image as will fit on the screen. The SUBSAMPLE keyword can
be used to select every 'n' lines and samples so that
representations of very large images may be displayed. The ZOOM
keyword can be used to enlarge a portion of an image on the
display screen. Keywords can be specified to begin displaying at
any line and sample in the image with the SL (starting line) and
SS (starting sample). If only a limited number of lines and
samples are to be displayed the NL (number of lines) and NS
(number of samples) keywords can be used. The UP, DOWN, LEFT and
RIGHT keywords can be used to display different portions of the
image, relative to the currently displayed portion. The display
can also placed at any point on the screen using the DSL (display
starting line) and DSS (display starting sample) keywords.
DISPLAY takes the following keywords :
SUBsample n a positive integral subsampling factor for
displaying images larger than the size of the
screen. SUB=2 would display an image at half
the resolution.
If the image lines and samples look like this:
sample values
line 1 1 2 3 4 5
line 2 6 7 8 9 10
line 3 11 12 13 14 15
Then the command DISP SUB 2 would produce:
sample values
line 1 1 3 5
line 2 11 13 15
ZOOM n a positive integral zoom factor for looking at
part of an image close up. The zoom command
replicates pixels by the integer value
specified.
If the image lines and samples look like this:
sample values
line 1 1 2 3
line 2 4 5 6
line 3 7 8 9
Then the command ``zoom 2" would produce the following:
sample values
line 1 1 1 2 2 3 3
line 2 1 1 2 2 3 3
line 3 4 4 5 5 6 6
line 4 4 4 5 5 6 6
line 5 7 7 8 8 9 9
line 6 7 7 8 8 9 9
CENTER center the display around current cursor position.
This command is very useful when displaying large
images or when zooming in on selected areas.
NL n
NS n number of lines or samples from the image file to
display
SL n
SS n starting line or sample within the image file to
display
UP n
DOWN n adjusts the starting line up or down from the
previous value, thereby moving the display window
up or down in the image. The default amount to
move up or down is the size of the display.
LEFT n
RIGHT n adjusts the starting sample left or right from the
previous value, thereby moving the display window
left or right in the image
DSL n
DSS n start the image display at the specified line and
sample on the display screen.
Examples: The user wants to display an entire Voyager image
(800 x 800) on the display screen then display a portion of the
image at full resolution. Type "FILE MIRANDA1.LBL", then "DISP
SUB 2" to display the entire image at half resolution, Use the
CURSOR command to move the cursor to the center of an area of
interest. Exit the cursor mode by typing ".", then type "DISP
CENT" to display the selected portion of the image at full
resolution.
The user wishes to place 2 images which are each 800 lines
by 800 samples on the screen next to each other. The first file
is opened with "FILE IMAGE1.IMG". The "DISPLAY SUB 4" command is
given to display every 4th line and sample of the image to create
a 200 x 200 display. Next the "FILE IMAGE2.IMG" command is given.
Now a "DISPLAY SUB 4 DSS 201" is given to place the second image
on the screen starting at display sample position 201, next to
the first image.
4.5.7 ERASE
The command ERASE causes the screen to be erased by setting
all of the pixels to 0, which may not necessarily be black
depending on the palette setting.
4.5.8 EXIT
The EXIT command exits IMDISP and returns the user to the
MSDOS operating system. The contents of the image display and
refresh buffer are discarded.
4.5.9 FILE
FILE does not take a keyword, just a value which is the file
name. The specified file will be opened, or an error message
issued if the file cannot be opened. The capability to directly
address any sector on the CDROM disk by providing its physical
address (minute, second and sector number) is also available to
users of the Microsoft Extensions software.
If the FILE command is specified without a filename, the
program will display a list of file names in the current
directory. Each file name is preceded by a number. Typing the
number associated with a file name will select that file for
processing. File names that actually represent lower level
directories are indicated with a <d> symbol after the name,
Directories can be traversed downward by selecting the number
associated with a directory name. Upward traversal is by
selecting the item identified as PARENT DIR. This will move
upward in the directory hierarchy.
The prompt mode clears the screen and displays a menu of
files and commands. These commands allows specification of the
default drive, a file "mask" to use in selecting file names for
display and options for moving through the list of files when the
current directory contain more than 30 files. The top line of the
display also indicates how many files are in the current
directory. After exiting the FILE prompt mode, the previous
contents of the display screen can be recovered by typing
"REFRESH".
The FILE prompt mode subcommands:
D select default disk drive
M specify a file selection mask to use in displaying
files on the screen.
N display the next set of file names on the screen
if there are more files in the current directory
than can be displayed on one screen.
P display the previous set of file names.
Q quit the file selection mode and return to IMDISP
command mode.
The N, P and Q commands are executed immediately. If the D
or M commands are selected, the user is prompted to enter a drive
letter or file mask.
If the file selected by the "FILE filename" or FILE prompt
mode has a valid label, either PDS or VICAR2, then the number of
lines and samples and the pixel size will be displayed. If the
file is unlabeled then the program will prompt for the values to
use for the number of lines and samples, the number of bits per
pixel, and the number of header bytes. PDS detached labeled
images can also be displayed. The specified file remains the
current file until a new FILE command is given. The FILE command
resets the SET DNLO and SET DNHI values to the minimum and
maximum for the pixel size (normally 0 and 255). If a specified
filename is not found in the current directory then an error
message is displayed.
If the unlabeled image has a regular format, that is a
uniform structure of repeating lines and samples, the user can
specify this information when prompted by the program. For
example, an image named ASTERIA.DAT with one 1422 byte header
block followed by an image composed of 370 lines by 450 samples
of 8 bit pixels would be processed as follows:
At the COMMAND: prompt type "FILE ASTERIA.DAT" The program will
display the message:
Input file does not have a proper label.
Input number of lines: 370 enter the value 370
Input number of samples: 450 enter the value 450
Input size of each sample: 8 enter the value 8
Input size of header label: 1422 enter 1422 for the
size of the foreign
label block).
The COPIM utility can be used to add a PDS label to the
beginning of such a file, so that it can be used subsequently
without having to specify all the parameters separately.
The physical address of a data block on the CDROM can also
be specified using the syntax 'FILE "CD:mm:ss:bb"', where mm is
the minute, ss the second, and bb the sector block number of the
beginning of the desired data area. The CD:mm:ss:nn must be in
double quotes and the CD must be capitalized! This mechanism can
be used to access files on non-High Sierra format disks. This
will only work on systems using the Microsoft Extensions
software.
4.5.10 HELP
HELP displays the online help message. If followed by the
name of a valid command the message for that command is
displayed. HELP is not provided for MSDOS commands (DIR, CHDIR,
CD and TYPE).
4.5.11 HISTOGRAM
The HISTOGRAM command produces a plot showing the number of
pixel values in the image at each DN level. The range of DN
values is displayed on the x-axis and the number of occurrences
of a specific DN value on the y-axis (See Figure 4-1).
The HISTOGRAM command reads through the image, calculates
the histogram, and then displays the plot on the screen. The
histogram is scaled so that the third highest histogram value is
used as the maximum. It is recommended that the SUBSAMPLE or
other subsetting keywords be used to speed up histogram
calculation, which can be quite slow for large images and for
images stored on CDROM. Histogram plots are displayed on top of
any image currently displayed on the screen, so the user may wish
to use the ERASE command to clear the screen prior to using
HISTO. After the histogram is displayed, the image can be
restored using the REFRESH command.
27582 | .
| ..
| ....
COUNT | .....
| .......
| .........
| ............
| ...............
--+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
0 64 128 192 256
DN value
Figure 4-1: Sample Image Histogram
By evaluating the histogram, the user can determine the
optimum settings for the SET (DNLO and DNHI) command to produce a
useful display. In the example above, the image data are
clustered between DN values 32 and 144. Using the default
settings of the EGA display mode the colors assigned to the 2
lowest color values and the 7 highest values (representing DN
values from 0 to 31 and from 144 to 255) would not be used since
the image contains no pixels with these values.
By using the "SET DNLO 32 DNHI 144" command the 16 display
levels available on the EGA display would be assigned to values
between 32 and 144 rather than distributed evenly from 0 to 255,
and all 16 colors would be used in the display.
HISTOGRAM takes the following keywords and arguments:
SUBSAMPLE n a integral subsample factor
for speeding up histogram use of
"HISTOGRAM SUBSAMPLE 4" is always
recommended
NL n
NS n number of lines and samples from image
SL n
SS n starting line and sample in image
CENT perform the histogram on only the displayed
portion of the image.
Two special keywords can be used with Voyager or Viking
images on the PDS CDROM disks. These will extract histogram
values stored with the image on the CDROM disk and reduce the
time required for the histogram to be generated from more than 1
minute to about 3 seconds. Note that these commands will not work
with Voyager image files in the \PLANET\JUPITER\ATMOS directory,
or with versions of system software written before April 1987.
VOY use histogram from Voyager CDROM engineering data
VIK use histogram from Viking CDROM engineering data
4.5.12 LABEL
The label command prints the labels for the currently selected
image file on the screen.
4.5.13 MENU
The menu command reads a file containing a list of file names and
places the user in the MENU mode, where files from this list can
be
selected for display. The MENU mode is similar to the FILE mode,
except that the list of files presented is that provided in the
menu
file, rather than from a selected directory.
The MENU mode can be invoked by typing "MENU filename.MNU" at the
COMMAND: prompt. It can also be invoked on program startup by
typing
"IMDISP filename.MNU" to initiate the program. The menu file must
use the ".MNU" extension to startup IMDISP in MENU mode.
Subcommands of the MENU mode are as follows:
# - Enter the number corresponding to a desired file name to select
the file.
P)revious - display the previous screen of file names
N)ext - display the next screen of file names
Q)uit - quit or exit from MENU mode
After selecting and displaying an image, the user can return to the
current menu by typing "MENU" at the COMMAND: prompt.
A menu file can take either of two formats. The preferred format
is a
PDS labelled table file containing file names. A sample file is
shown
below:
NJPL1I00PDS100000000 = SFDU_LABEL
FILE_TYPE = TABLE
RECORD_FORMAT = STREAM
OBJECT = FILE_NAME
TYPE = LITERAL
LENGTH = 80
ENDOBJECT
NOTE = "Sample MENU file for IMDISP"
END
L:\OCEAN\SCBMEAN.IMG
L:\OCEAN\WCMEAN.IMG
L:\PLDS\TMCH01.DAT
L:\PLDS\DEM.DAT
L:\PLANET\SATURN\ATMOS\C3497355.IMG
<END OF FILE>
A second abbreviated form may also be used, where only the
filenames are specified in the ".MNU" file. In this case the
file would only contain the filenames shown after the END
statement in the example above.
4.5.14 OVERLAY
The OVERLAY command draws a lat/lon overlay grid on the displayed
image. It is intended only for use with the Ocean Data System,
West Coast Time Series CDROM in this program version.
The OVERLAY command has the following arguments:
MAXLAT Latitude of top of image.
MINLAT Latitude of bottom of image.
MAXLON Longitude of left side of image.
MINLON Longitude of right side of image.
LEGend Draw a color scale with the overlay.
4.5.15 PALETTE
The PALETTE command is used for changing the colors assigned
to displayable color values. This is done by modifying an
internal color table which assigns intensity values for red,
green and blue to a color value, The EGA provides 4 intensity
values for each of 3 colors, so that 64 different colors can be
created. However, the EGA pixels are only 4-bits each so only 16
color values can be used simultaneously.
The palette can be modified using the EDIT command and saved
and loaded from a disk file. The edit mode is invoked by typing
PALETTE EDIT. With the EGA display, a bar containing 16 colors or
shades will be displayed on the bottom of the screen. A small
square will appear in the middle of the center color box. This
indicates that this color value is currently selected for
editing. To select another color value for editing, move the
small square to the appropriate color using the "4" (left arrow)
and "6" (right arrow) keys on the numeric keypad. The color of
the current color box is changed with the "R", "G", and "B" keys
(for red, green, and blue). Upper case letters increase the
amount of the primary color, and lower case keys decrease the
amount of the color. The "8" (up arrow) and "2" (down arrow) keys
increase and decrease, respectively, the amount of red, green,
and blue simultaneously. Other commands in the palette edit mode
are the "s" command, which will shift all colors one value to
the right, and the "x" command, which will exchange color values
(the color setting for color 0 becomes the setting for color 15,
while 15 replaces 0, the color setting for color 1 becomes the
setting for 14, while 14 replaces 1, etc.). The up and down
arrow keys can also be used to cycle through the colors available
in a given display mode one at a time. Type the "." key or
carriage return to exit the edit mode.
PALETTE takes the following keywords and arguments:
EDIT n to interactively adjust an n-color
palette.
See edit description (above) for details
PSEUDOCOLOR n PS = 0 for default palette,
PS = 1 for gray scale palette,
PS = 2 for pseudo color palette
SAVE filename saves the specified palette on disk
LOAD filename loads the specified palette from disk
The default palette file for LOAD or SAVE operations is
IMDISP.PAL. The format of the default color palette when stored
in a palette file is as shown below:
NJPL1I00PDS000000784 = PDS_SFDU_LABEL
FILE_TYPE = TABLE
RECORD_TYPE = STREAM
FILE_RECORDS = 28
TABLE_ROWS = 16
ROW_COLUMNS = 4
COLUMN_NAME = (COLOR_NUMBER,
RED_VALUE,
GREEN_VALUE,
BLUE_VALUE)
COLUMN_TYPE = (INTEGER,INTEGER,INTEGER,INTEGER)
END
0 0 0 0
1 64 0 0
2 128 0 0
3 192 0 0
4 192 64 0
5 192 128 0
6 192 192 0
7 128 192 0
8 0 192 0
9 0 192 128
10 0 128 128
11 0 128 192
12 0 0 192
13 128 0 192
14 192 0 192
15 192 192 192
The first column of the palette table is the color value
number for the display, and columns 2, 3 and 4 represent the
intensity of the red, green and blue (respectively) primary
colors on a scale of 0 to 255. With the EGA display these values
are: 0 = off; 64 = low; 128 = medium; 192 = high.
4.5.16 PROFILE
PROFILE plots the DN values of pixels located along a line
between two points in the image, i.e. it creates a graph of DN
value versus pixel along the line joining the two points, Cursor
mode is used to select the two endpoints; typing "." or carriage
return selects the current cursor position as the endpoint. After
the endpoints are selected a line is drawn between the points and
the graph is plotted at the bottom of the screen, showing the DN
values on the x-axis and the positions along the line on the y-
axis.
4.5.17 QUIT
Exits the program. The contents of the image display and
refresh buffer are discarded.
4.5.18 REFRESH
REFRESH redisplays the image plane from the refresh buffer.
When images are written to the screen they are also written to
the refresh buffer. The REFRESH command writes this buffer back
to the screen, thereby erasing any graphics or text overlaying
the image on the screen. The refresh buffer contains as many
lines from the display screen as there is room for in memory.
REFRESH takes,es no parameters. It can also be used after the
FILE prompt mode to redisplay the contents of the refresh buffer.
Refresh is commonly used after the HELP command, or after a
HISTOGRAM or PROFILE command to remove text and plots from the
display screen.
4.5.19 SAVE
The SAVE command copies the contents of the display screen
to a file. On EGA systems the display buffer contains only
4-bits per pixel, so specifying BP = 8 will write the 4-bit
pixels in full bytes, but does not save full 8-bit pixels even
if the input image is an 8-bit image, Use the COPIM utility
program to produce a full resolution subset of an 8-bit image.
SAVE takes the following arguments and keywords, where the
filename must immediately follow the SAVE command:
filename filename of image to save
NL n
NS n number of lines and samples to save
SL n
SS n starting line and sample to save
BP n number of bits per pixel in output image
Example: Save a 200 line by 200 sample area at the center of
an image in the file SMALL.IMG. First use the FILE command to
select and display an input image. Now type:
"SAVE SMALL.IMG SL 100 SS 210 NL 200 NS 200"
to save the portion of the image beginning at line 100 and sample
210 in the new file SMALL.IMG.
4.5.20 SET
SET is used to display and change the DN (pixel value) range
that is used to compress the pixel values to the range
appropriate for the display device. The default, which is reset
for each new file, is the full range of DN values for the
particular pixel format (e.g. 0 to 255 for byte). It is also used
to specify a file name to be used by the browse command.
The results of a SET command will not take effect until the
next DISPLAY command is performed.
Set takes the following keywords:
DNLOW n
DNHIGH n where values less than DNlow are set to color
value 0, values greater than DNHIGH are set to
the maximum color value available, and the
color values between are assigned equally to
the DN values between Dnlow and DNhi.
BROwse filename sets a file name to be used for the
browse file. This file name will override the
default file name, which is 'c:browse.cmd'.
For example, using the default color palette and an EGA
display with 16 color values available, the command "SET DNLO 100
DNHI 164" will assign DN values below 100 to black and DN values
above 164 to white, and spread the 16 color values between the DN
limits, thus each color value will represent 4 DNs (value 0 = DN
100 to 103; value 1 - DN 104 to 107, etc.).
If values other than the default are used then the images
will display more slowly because scaling divisions are required.
SET with no parameters will display the current values.
The DNLO and DNHI values are reset to the minimum and
maximum for a given pixel size when a FILE command is issued.
4.5.21 STRETCH
STRETCH sets the palette to a gray scale stretched between
the two specified pixel values. Stretch is most useful on the PGA
display where 16 gray levels are available. On the EGA display
the stretch command activates the gray level palette which
provides only 4 gray levels. Use the PAL PS 0 command to return
the display to the default palette after performing a stretch.
STRETCH takes the following keywords :
LOW n
HIGh n the low and high DN values of the stretch.
These pixel values refer to the DN values in the current
image display, not necessarily in the original image (scaling may
have been involved). For example with the EGA display the DN
values in the display range from 0 to 15, even if a byte image is
being displayed.
The STRETCH command is not recommended for use on EGA systems.
4.5.22 SYSTEM
The SYSTEM command is used to send a command to MSDOS.
For example "SYS L:" will set the L: drive as the current
default drive. If there is not enough memory available for the
system command to be executed an error message is displayed. The
SYS command will not work on floppy disk systems unless the file
"COMMAND.COM" is present on the floppy disk with the IMDISP
program.
4.5.23 TEXT
The text command can be used to display a string of text on the
screen. The text string can be entered on the command line,
enclosed
in apostraphies or quotes (e. g., TEXT `This is a text string').
If the text string is not entered on the command line the program
will
prompt for the string to be displayed.
Once the command is issued and the text string entered the program
is
placed in CURSOR mode so that the display position can be selected.
This is done by using the arrow keys to move the cursor to the
desired
location. After the position is selected, the user types a period
(.)
or carriage return and the text will be written on the display
screen.
The TEXT command has one argument and two optional keywords.
LINe The line number to position the text at.
SAMple The sample number to position the text at.
'text...' The text string to be printed, enclosed in
quotes or apostraphies.
The text command writes over image data in the display and
refresh buffer, thus the underlying portion of the image is lost.
4.5.24 TYPE
The TYPE command is used to type the contents of a text file
on the display screen, using the standard MSDOS type command.
Its argument is passed to MSDOS for execution. At the end of
the type operation the screen will display "Type carriage return
to continue:" which will return to the IMDISP command mode. If
there is not enough memory available for the system command to be
executed an error message is displayed.
4.6 OTHER UTILITY PROGRAMS
There are several utility programs also provided on the
distribution disk. (Note: these are not available on the floppy
disk).
4.6.1 COPIM
(Not available on floppy disk; only on CD-ROM)
Chapter 5
COMMAND SUMMARY
Within this command summary listing, brackets ([]) indicate
optional parameters or keywords. Filename is the name of a file
in the current directory or a fully qualified filename which can
include drive letter and pathname. Directory name is an MSDOS
directory path specification, a valid directory mask a
specification containing wild card characters (*, ?) per MSDOS
rules for wildcard use in the DIRECTORY command. The symbol "n"
is used to indicate an integer value.
driveletter:
BATCH [filenamel
BROWSE [directory mask] [SIZ n] [SUB n] [NOLabel]
CD [directory name] [..]
CURSOR
DIRECTORY [directory mask] [/w]
DISPLAY [SUB n] [SL n] [SS n] [NL n] [NS n] [BP n]
[CENT] [DSL n] [DSS n]
ERASE
EXIT
FILE [filename] ["CD:mm:ss:bb"]
HELP [command name]
HISTOGRAM [SUB n] [SL n] [SS n] [NL n] [NS n] [BP n] [CENT]
LABEL
MENU [filename]
OVERLAY [MAXLAT n] [MAXLON n] [MINLAT n] [MINLON n]
[LEGend]
PALETTE [EDIT n] [PS n] [LOAD filename] [SAVE filename]
PROFILE
QUIT
REFRESH
SAVE filename [SL n] [SS n] [NL n] [NS n] [BP n]
SET [DNLO n] [DNHI n] [BROwse filename]
STRETCH [LO n] [HI n]
SYSTEM [MSDOS command]
TEXT [LINe n] [SAMple n] "text" or 'text'
TYPE filename
