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Text File | 1991-12-04 | 34.2 KB | 949 lines

PL.HLP : Help file for Piclab 1.91
Compiled 12/3/91

~MAKEPAL

Syntax: MAKEPAL

Makes a palette appropriate for the NEW buffer.  Operates on only
true-color images.  The variable PALETTE determines the number of
colors in the new map, and the MAKEPAL command picks that many colors
to best fit those in the image.

The MAP command must be used to map the image onto the palette.

~EGAPAL

Syntax: EGAPAL

Makes a 16-of-64-color palette appropriate for the NEW buffer.
Operates on only true-color images.  This is designed primarily for
reducing full-color images to a form better suited for display on
an IBM EGA or similar device.

The MAP command must be used to map the image onto the palette.

~MAP

Syntax: MAP

Maps NEW buffer onto the current palette.  Operates only on true-color
images, and produces a color-mapped image.  The variable DITHER
determines whether each pixel is simply mapped onto the nearest color
in the map, or whether dithering is used to achieve a more accurate
mapping.  DITHER defaults to ON, and is recommended for most uses.

The MAKEPAL command should be used to create the best possible palette
for the image before mapping, but any palette may be used for special
purposes such as mapping several images to the same palette.

~PLOAD

Syntax: PLOAD file [offset [count]]

Loads a MAP file into the current palette.  First argument is the name
of the MAP file which is assumed to be in the PICDIR directory.  If a
second argument is given, the palette is loaded starting at that index.
If a third argument is given, only that many colors are loaded.

MAP files are plain text files that contain the RGB values for each
palette index on one line.

~PSAVE

Syntax: PSAVE file [offset [count]]

Saves a MAP file from the current palette.  First argument is the name
of the MAP file which is assumed to be in the PICDIR directory.  If a
second argument is given, the palette is loaded starting at that index.
If a third argument is given, only that many colors are loaded.

This can be used to save a palette created with MAKEPAL so that it need
not be calculated again, or so that it can be used with other images.

MAP files are plain text files that contain the RGB values for each
palette index on one line.

~GRAYPAL

Syntax: GRAYPAL file [offset [count]]

Makes the specified MAP file the default colors used when displaying
monochrome images or full-color images on a VGA.  The default colors
are equivalent to GAMMA1.MAP, but GAMMA2.MAP and PSEUDO.MAP can be
useful in some situations.

MAP files are plain text files that contain the RGB values for each
palette index on one line.

~UNMAP

Syntax: UNMAP

Produces a true-color image from a color-mapped one.  This must be done
before applying true-color transformations such as rescaling.  After
transformations have been performed in true-color, the image may be
reduced to a color-mapped one again with the MAKEPAL and MAP commands.

~HELP

Syntax: HELP [subject]

Looks like you have figured this one out already.

~CALL

Syntax: CALL program [args]...

Calls the external program named by its first argument passing along
any subsequent arguments to that program.  Many programs do not
release all of the memory given to them when they terminate, so
Piclab will reserve a large portion of memory for itself before
calling a program.  If you do not have much more memory than Piclab
reserves, this may result in the program not being able to run in the
memory left.

If this is a problem, you can use the DOS or SHELL commands to exit
to DOS with all of the free memory available.

~CANCEL

Syntax: CANCEL

Cancels the most recent operation.  If there are point
transformations pending that have not yet been saved with the
TRANSFORM command, these are cancelled and no changes are made to the
edit buffers.  Otherwise, the NEW and OLD buffers are exchanged.

There are some operations (like SAVE) that do not alter the edit
buffers.  If one of these operations was the last one performed, UNDO
will undo the operation before that.  No arguments.

~UNDO

Syntax: UNDO

Cancels the most recent operation.  If there are point
transformations pending that have not yet been saved with the
TRANSFORM command, these are cancelled and no changes are made to the
edit buffers.  Otherwise, the NEW and OLD buffers are exchanged.

There are some operations (like SAVE) that do not alter the edit
buffers.  If one of these operations was the last one performed, UNDO
will undo the operation before that.  No arguments.

~SHELL

Syntax: SHELL [command]

Calls up the DOS command line.  All available memory is released to
DOS when this command is given, and is reclaimed when DOS is exited.
For this reason, some programs that cannot be CALLed may be run from
with DOS.

Any arguments to this command will be passed to the system as a
command line, and will cause it to return immediately after the
command is done.  One particularly useful action of this program is
"SHELL COPY /B PDAT PRN", which copies the print file to the printer.
"SHELL DIR" can be used to view file directories when you want to see
all files, not just pictures.

~DOS

Syntax: DOS [command]

Calls up the DOS command line.  All available memory is released to
DOS when this command is given, and is reclaimed when DOS is exited.
For this reason, some programs that cannot be CALLed may be run from
with DOS.

Any arguments to this command will be passed to the system as a
command line, and will cause it to return immediately after the
command is done.  One particularly useful action of this program is
"DOS COPY /B PDAT PRN", which copies the print file to the printer.
"DOS DIR" can be used to view file directories when you want to see
all files, not just pictures.

~QUIT

Syntax: QUIT [flag]

Exits Piclab.  If there is a point transformation pending, it must be
cancelled or saved before exiting.  If the exit command is given any
arguments, it exits immediately regardless of pending transformations.

Inside a program, QUIT merely sets a flag so that Piclab will exit after
the program is complete.

~EXIT

Syntax: EXIT [flag]

Exits Piclab.  If there is a point transformation pending, it must be
cancelled or saved before exiting.  If the exit command is given any
arguments, it exits immediately regardless of pending transformations.

Inside a program, EXIT merely sets a flag so that Piclab will exit after
the program is complete.

~LIST

Syntax: LIST [item]

If given without an argument, shows what things may can be listed.
If one of these things (e.g. FORMATS, COMMANDS, BUFFERS) is given as
an argument, the appropriate items are listed.  Especially useful are
LIST COMMANDS if you forget the name of a command you are looking for
and LIST BUFFERS to check the size and format of the image in the OLD
and NEW edit buffers.

~PAUSE

Syntax: PAUSE [time]

With no arguments, Piclab waits for a key to be pressed before
continuing.  If one argument is given, Piclab waits for that number
of seconds (but will break early if a key is pressed).  This is for
use within programs.

~PRINT

Syntax: PRINT [x-offset [y-offset]]

Prints the image in the NEW buffer into the file specified by the
PRINTFILE variable.  The current setting of the PRINTER variable
determines what codes are sent to the file.

For hard-to-explain reasons, the current release of Piclab does not
allow the use of a device name such as PRN in the PRINTFILE
variable.  Images must therefore be printed to disk and copied to the
printer with DOS.

If arguments are given, the first two are used as the X and Y offsets
of the first dot to print on the first page of output.

~RUN

Syntax: RUN program [ECHO]

Takes one argument--the name of a text file containing Piclab
commands.  These are interpreted as if they had been typed from the
command line, but they are not echoed, and messages are turned off
while a program runs.  If a second argument to the RUN command is the
word ECHO, messages are not turned off.

A program can also be run by giving its name as an argument to the PL
command when starting Piclab.

~SHOW

Syntax: SHOW [x-offset [y-offset]]

Used to display as much of the image in the NEW buffer as will fit on
the computer's display screen.  If arguments are given, the first is
used as a horizontal offset into the image buffer and the second as a
vertical offset.  This can be used to look at different parts of an
image too big for the screen.  Certain video modes allow scrolling
with the arrow keys, but not all.  If no arguments are given, the
current values of the XORIGIN and YORIGIN variables are used.

If any point transformations are pending, the image you see on screen
reflects the image as it would be AFTER the pending transformation.
This can be used to look at the effect of a transformation before
saving or cancelling it.

Because Piclab often stores data more accurately than the display can
render it, what you see on the screen is only an approximation of the
actual image.  In particular, because Piclab does not yet support any
true-color display hardware, true-color images will be shown in grayscale
on displays capable of it, or in 8-color dither on others.

~SET

Syntax: SET [variable [value]]

Without any arguments, lists all Piclab variables and their current
values.  Variables can be numbers, character strings, or TRUE/
FALSE.  Variables set system defaults and control the specifics of
how many commands perform.

If the set command is given one argument, the variable named is
cleared.  That is, set to 0 if it is numeric, to "" if it is a
string, and to FALSE if it is TRUE/FALSE.

If SET is given with two arguments, the variable named by the first
is set to the value specified by the second.  If a numeric variable
is given a string value, it is set to 0.  String values should not be
put in quotes.  TRUE/FALSE values may be set by the keywords
TRUE/FALSE, YES/NO, ON/OFF, or by the numeric values 1/0.

Within the SSTOOLS.INI file, the syntax is <variable>=<value>.

Help on individual variables is available by typing HELP <variable>.

~HISTOGRAM

Syntax: HISTOGRAM [RED | GREEN | BLUE]...

If no arguments are given, plots histograms for all planes; if one or
more arguments are given, a histogram is plotted for each plane
specified as an argument.  The histograms plotted reflect the image
as it would be after any pending transformations, so you can look at
the results of many processes before saving or cancelling them.

Each vertical bar of the histogram represents the total number of
pixels in the image with values in the range beginning with the value
listed below the histogram in hexadecimal.  Each bar covers a range
of four values and there are 64 bars.  The height of each bar is in
logarithmic proportion to the frequency of occurrence of values in
the range it represents.  The bars are automatically scaled so that
the tallest one is made 20 characters high.

~NEGATE

Syntax: NEGATE [RED | GREEN | BLUE]...

Arguments are handled as in HISTOGRAM.  Inverts each value in the
lookup table for the planes specified.  This can be used after
digitizing a negative or for special effects.

~DARKEN

Syntax: DARKEN [[RED | GREEN | BLUE] value]...

Subtracts a constant value to each point in the planes specified.  If
only one argument is given, all planes are brightened by that amount.
Otherwise, arguments are interpreted in order, and any arguments that
specify planes determine which plane the next numerical argument will
affect.  For example, DARKEN RED 10 BLUE 15 would subtract 10 from
the values in the red plane and 15 from those in the blue.  Any
values that would be taken out of the 0..255 range by the transform
are clamped.

Because this darkening is a linear operation, the image to be
brightened or darkened should be encoded with a gamma of 1.0.  That
is, there should be a linear relationship between values in the image
and intensities on the display.  If this is not the case, gamma
correction may be applied with the GAMMA command before adjusting
brightness.

~BRIGHTEN

Syntax: BRIGHTEN [[RED | GREEN | BLUE] value]...

Adds a constant value to each point in the planes specified.  If only
one argument is given, all planes are brightened by that amount.
Otherwise, arguments are interpreted in order, and any arguments that
specify planes determine which plane the next numerical argument will
affect.  For example, BRIGHTEN RED 10 BLUE 15 would add 10 to the
values in the red plane and 15 to those in the blue.  Any values that
would be taken out of the 0..255 range by the transform are clamped.

Because this brightening is a linear operation, the image to be
brightened or darkened should be encoded with a gamma of 1.0.  That
is, there should be a linear relationship between values in the image
and intensities on the display.  If this is not the case, gamma
correction may be applied with the GAMMA command before adjusting
brightness.

~CONTRAST

Syntax: CONTRAST [[RED | GREEN | BLUE] value]...

This stretches or squeezes the contrast of an image.  Arguments are
interpreted like those in BRIGHTEN.  If a given value is positive,
the image contrast is stretched so that values that were equal to the
given value become 0, and those that were equal to (255-value) become
255.  If the given value is negative, the inverse operation is
performed.  Because contrast is always stretched equally around the
midpoint of the range, it is a good idea to brighten or darken an
image as necessary to center its histogram before performing a
contrast stretch.

Also, the contrast stretching formula operates on color values
assuming a linear relationship between these values and the
intensities they represent (as do the BRIGHTEN and DARKEN commands).
Therefore, if an image has been scanned with a device with a gamma
value not equal to 1.0, the image should be gamma corrected before
contrast stretching.

~GAMMA

Syntax: GAMMA [[RED | GREEN | BLUE] value]...

The color values of the specified planes are adjusted so that values
encoded for display on a monitor with a gamma value equal to the
argument become linear.

For example, images encoded for display on PCs usually expect a
monitor with a gamma near 2.0.  The GAMMA 2.0 command will convert
these values to a linear scale.

Images encoded on Macintoshes and similar equipment have linear
values already.  Such images can be adjusted for display on PCs with
the inverse transformation, i.e. GAMMA 0.5.

See Piclab.DOC for more background on gamma correction.

~COLOR

Syntax: COLOR [mapfile]

Converts a grayscale image into a color-mapped image.  If the first
argument is the name of a MAP file, the image is pseudo-colored with
that map, otherwise the color map will contain the original grays.

~GRAY

Syntax: GRAY

Converts true-color or color-mapped image to grayscale.  The formula
used for conversion to grayscale is the same as used by black and
white televisions and is designed to mimic the eye's response: gray =
(.287 * red) + (.589 * green) + (.114 * blue).

~TRANSFORM

Syntax: TRANSFORM

Saves the result of a series of point-process transformations to the
edit buffer.  This must be done before any other transformation may
be performed on the image.  If you wish to cancel the pending
transformations without saving them, use UNDO or CANCEL.

~MEDIAN

Syntax: MEDIAN [WEIGHTED]

Reduces spot noise in an image.  Each point is replaced by the median
of the points in its 3 x 3 area.  That is, the nine points in this
area are sorted and the fifth one is taken.  If the one argument to
this routine is WEIGHTED, then the center point is added twice more
to the list and the sixth of the 11 points is taken.

The median filter results in some smoothing, but not as much as with
the SMOOTH command.  This effect is a little less drastic with the
weighted median filter.  Repeated application of this operation will
result in an oil-paint texture appearing on the image.

This filter will not help reduce periodic or other noise--only small
spot noise such as from dust on a lens.

~SHARPEN

Syntax: SHARPEN [value]

Applies what is called (somewhat inaccurately) a LaPlace transform to
the image.  The effect is that edges in the image are sharpened as if
the image had been re-focused.  Unfortunately, it also increases the
amount of noise in the image, making it appear more grainy.

The command can be given a single numerical argument, which specifies
the severity of the transform.  It is basically a tradeoff between
sharpness and noise, and defaults to 1.0.  This value provides a
noticeable increase in both sharpness and noise, and is about the
best value for sharpening when the purpose is to bring out
information.  When applying to a real image, a less severe value of
.2 to .5 is often better.  Values greater than 1.0 should be used
only when trying to locate specific objects in an image.  They
produce too much noise for accurate reproduction.

This function works by amplifying the differences between each point
and its neighbors.  This has the effect of amplifying high spatial
frequency details such as edges and noise.

~SMOOTH

Syntax: SMOOTH [value]

Replaces each point with the average of the values of the nine points
in its neighborhood.  This has the effect of smoothing the image and
reducing high frequency effects like aliasing and noise, as well as
high frequency details.  If an argument is given, it is taken as a
value of the severity of the transform as with the SHARPEN command. A
value of 1.0 is exactly as described.  Values less than 1.0 change
the center value less than if a straight average had been done.
Values greater than 1.0 are not recommended.  If more smoothing is
desired, perform SMOOTH more than once rather than with a high value.

~ADD

Syntax: ADD [WRAP]

Adds the OLD and NEW edit buffers storing the result in the NEW
buffer.  If the only argument to the command is WRAP, then values
that are taken out of the 0..255 range by the addition are taken mod
255; otherwise, values are clamped.

~SUBTRACT

Syntax: SUBTRACT [WRAP]

Subtracts the NEW edit buffers from the OLD buffer storing the result
in the NEW buffer.  If the only argument to the command is WRAP, then
values that are taken out of the 0..255 range by the addition are
taken mod 255; otherwise, values are clamped.

~AVERAGE

Syntax: AVERAGE

Averages the OLD and NEW buffers, storing the result in NEW.  This
can be used to reduce random digitizer noise by averaging the results
of different samplings.  Can also be used to produce a double exposure
effect when two different images are averaged.  No arguments.

~CLIP

Syntax: CLIP [x-size y-size]

If no arguments are given, image is clipped from (XORIGIN,YORIGIN) to
lower right corner (upper right for bottom-up images).  If two
arguments are given, the image is clipped from (XORIGIN,YORIGIN) to
the horizontal and vertical size specified by the arguments.  XORIGIN
and YORIGIN are set to 0 after this operation.  One argument is an
error; more than two are ignored.

~EXPAND

Syntax: EXPAND x-size y-size [(BLACK | WHITE | value) [value]...]

This command increases the size of the image to the width and height
specified by its first two arguments by adding extra rows and columns
of pixels.  If a third argument is given, it can be either BLACK or
WHITE to indicate what color the extra pixels should be.  If three
numeric arguments are given after the bounds arguments, they are
taken as the red, green, and blue value of the extra pixels.

Multiple images can be placed in a montage by using EXPAND and
OVERLAY.  Parts of an image may be joined with these functions as
well, but it is not recommended for separately digitized image
pieces, as no mosaicking is performed.

For color-mapped images, the third argument is treated as a color map
index rather than a color value.

~MIRROR

Syntax: MIRROR

Flips the image horizontally.  No Arguments.

~OVERLAY

Syntax: OVERLAY [x-offset [y-offset [threshhold]]]

Overlays the image in the NEW buffer on top of the OLD buffer.  The
image in the NEW buffer must not be larger than the image it is to
overlay.  If two arguments are given, they are used as the horizontal
and vertical offsets into the base image at which the overlay image
is to be placed.  Otherwise, XORIGIN and YORIGIN are used.

If a third argument is given, all values in the overlaying image less
than the give threshhold are treated as transparent.  This feature is
primarily for grayscale and color-mapped images.  Using it on full
color images produces bizarre results, because the threshholding is
applied to each RGB component separately, rather than to the whole
color value.

~RESCALE

Syntax: RESCALE value | (x-size y-size)

Resamples the image at a different resolution.  This is useful for
scaling images up to a larger size for printing, or for scaling them
down for display.  It is recommended that image data always be saved
at its original sampling resolution to preserve as much data as
possible and only scaled when necessary to conform to hardware.

If only one argument is given, horizontal and vertical resolution are
both increased in the given proportion.  E.g., if a 320 x 240 image is
in the NEW buffer when RESCALE 1.5 is given, the NEW buffer will
contain the same image at 480 x 360.

When two arguments are present, they are treated directly as the new
resolution of the image.  The above command could be expressed as
RESCALE 360 480.  This is most often used to compensate for differing
aspect ratios.  For example, a 320 x 400 from an Amiga can be rescaled
to 320 x 200 to be viewed on a VGA.

RESCALE cannot be used on color-mapped images.

~REVERSE

Syntax: REVERSE

Changes the storage order of an image from top-down to bottom-up or
vice versa.  This is used primarily to save an image loaded from a
file in one format (like PCX) to a format requiring the opposite
order (like GIF).

Targa files can be stored either way, and contain information in the
header specifying which way they are stored.  Thus, any image can be
saved in Targa format at any time with minimal memory usage.

~ROTATE

Syntax: ROTATE value

Rotates image in 90-degree increments.  The single argument is
the number of degrees through which to rotate.  Only 90, 180, and
270 are currently supported (well, 0 and 360 work too, but they
aren't very exciting.)

This is very useful for rotating screen-oriented images for printing
on paper.  Because this operation requires large amounts of memory
for large images, it is recommended in this case to rotate the image
before scaling it up to size for printing.

~DIR

Syntax: DIR [directory]

Lists all files in the PICDIR directory in the current file format.  If
an argument is given, files in that directory are listed.  No other
file specifications can be given.  If FILEFORMAT is set to GIF or
TARGA, statistics on the files will be listed as well.

~GDIR

Syntax: GDIR [directory]

Lists only GIF files from PICDIR or from the directory given as sole
argument.  Statistics are listed from each file as well.

~TDIR

Syntax: TDIR [directory]

Lists only Targa files from PICDIR or from the directory given as
sole argument.  Statistics are listed from each file as well.

~LOAD

Syntax: LOAD file [args]...

Loads a file in the current file format into the NEW buffer, moving
the current contents of the NEW buffer to OLD.  Any arguments are
passed along to the function that handles loading for the current
format and are interpreted by that routine.  The first argument is
always the file to be loaded, but other arguments vary with the format.

LIST FORMATS will give you a list of all the available file formats,
and HELP is available for each.

~GLOAD

Syntax: GLOAD file

Loads image in GIF format regardless of the current setting of
variable FILEFORMAT.  Sole argument is filename.

~TLOAD

Syntax: TLOAD file

Loads image in Targa format regardless of the current setting of
variable FILEFORMAT.  Sole argument is filename.

~RLOAD

Syntax: RLOAD file x-size y-size [COLOR | MONO]

Loads image in RAW format regardless of the current setting of
variable FILEFORMAT.  The width and height of the image must be
specified as the second and third arguments to RLOAD.  A fourth
argument may be either of the words COLOR or MONO to specify the
number of planes.  COLOR is default.

Color-mapped RAW files must be loaded as MONO, then colored with the
COLOR command after the palette is loaded with PLOAD.

~SAVE

Syntax: SAVE file [args]...

Saves the image in the NEW buffer to the file specified by the first
argument.  Subsequent arguments are passed along to the file save
routine of the current file format.

LIST FORMATS will give you a list of all the available file formats,
and HELP is available for each.

~GSAVE

Syntax: GSAVE file [INTERLACE]

Saves the NEW buffer to the file named by the first argument in GIF
format regardless of the current setting of variable FILEFORMAT.  If
the second argument is the word INTERLACE, image is interlaced.

~TSAVE

Syntax: TSAVE file [bits]

Saves the NEW buffer to the file named by the first argument in Targa
format regardless of the current setting of variable FILEFORMAT.  If
the second argument is 16, 24, or 32, it is used as the number of
bits per pixel stored in the file.

~RSAVE

Syntax: RSAVE file

Saves image in RAW format regardless of the current setting of
variable FILEFORMAT.  No arguments.

~XORIGIN

Used to set the left limit of an image for operations such as CLIP
and SHOW.  Legal values are 0..(image width - 1).

~YORIGIN

Used to set the upper limit of an image for operations such as CLIP
and SHOW.  Legal values are 0..(image height - 1).  If image in NEW
buffer is stored with bottom-up raster, YORIGIN is measured from the
bottom counting upwards.

~PALETTE

Number of colors in palette for palette mapping operations.  Valid
values are 2..256.

~DPI

Graphics resolution for LaserJet printing.  May be 75, 150, or 300.

~MULTIIMAGE

T/F flag for GIF loading.  If true, Piclab will assume that any GIF
files to be loaded may contain multiple images and will act
accordingly.  This requires more memory, so it defaults to FALSE.

~MULTIMAP

T/F flag for GIF loading.  If true, Piclab will assume than any GIF
files to be loaded may contain multiple images, and further, that
each image may contain a local color map that differs from the global
map.  This takes three times the memory of MULTIIMAGE mode, so it
should be used only when absolutely necessary.

~DITHER

T/F flag used by the MAP command to determine whether or not
dithering is performed.  Defaults to TRUE, and is recommended.

~DISPLAY

Selects display type for SHOW command.  LIST DISPLAYS will list the
available modes and HELP is available for each.

~PRINTER

String variable indicating what type of printer the PRINT command
should address.  For a list of legal values, type LIST PRINTERS.

~PRINTFILE

Disk file to which the PRINT command is directed.  If blank, as is
the default, printing is sent directly to LPT1.

~PRINTSCALE

*** NOTE: The PRINTSCALE variable is not implemented.  What follows is
a description of what it will do when I get around to writing it.

Printer output is scaled up by this factor when printing.  This can
be used to print large banners and posters.  If the image after
scaling is wider than the paper, it will be printed in strips.

~TEMPDIR

Name of the drive and directory where Piclab stores its temporary
files (including the NEW and OLD edit buffers).  This directory must
have six bytes free for every pixel in an image with which you intend
to work plus some overhead.  This defaults to the setting of the TMP
environment variable.

~PICDIR

Directory in which picture files are stored.  If you use the DIR,
LOAD, and SAVE commands without specifying a directory, they will
look here.

~MAPDIR

Directory in which MAP files are stored.

~FILEFORMAT

Default file format for DIR, LOAD, and SAVE commands.  To operate on
most file formats it is necessary to set this variable
appropriately.  GIF and TGA are special:  separate commands (GDIR,
TLOAD, etc) exist to load and save these formats regardless of
current setting.  For legal values, type LIST FORMATS.

~SILENT

This variable is not listed, but can be set from the SSTOOLS.INI
file.  Its only function is to supress the program ID that prints
when Piclab is started.

~LEAVETEMPS

If this hidden variable is set to TRUE, the temporary file that
Piclab creates will not be deleted upon exit.  This can be used to
optimise performance by placing the temporaries in a fixed location.

~HELPFILE

Hidden variable identifying the HELP file.  This defaults to PL.HLP,
but can be set in the SSTOOLS.INI file to anywhere.

~TARGA

Truevision Targa and Vista format.  No arguments are needed to the
LOAD command.  For the SAVE command, if the second argument is 16,
24, or 32, it is used as the number of bits per pixel in the file.

~PPM

Jeff Poskanzer's Portable Pixmap format.  Piclab supports gray (PGM)
and color (PPM) formats, but not bitmaps (PBM).  DIR command only
lists files with extension of PPM, so you may want to use that for
all PPM and PGM files.

This format does not support mapped images.

~GIF

No arguments are interpreted from the command line, but GIF loading
is affected by the values of the variables MULTIIMAGE and MULTIMAP.
These are both set false by default to save memory, but one or both
may be necessary to load some files.  LOAD will issue warnings when
loading a multiimage or multimap file with improper settings.

If the word INTERLACE is given as an argument to the SAVE command,
the file is stored in GIF interlaced format.  A GIF file is always
saved as a single-image file with the screen size and image size
identical.  Because color GIF files are limited to a palette of 256
colors, only monochrome and mapped images can be saved.

'GIF' and 'Graphics Interchange Format' are trademarks of
CompuServe Incorporated, an H&R Block company.

~RIX256

Only uncompressed 256-color file formats from ColoRix are
supported--the old EGAPaint files are not.  Because so many different
file extensions are used, file extension must be specified when
loading.  The global palette is taken from the image file regardless
of the file extension, unlike ColoRix.

The SAVE command is not supported for this format.

~IP

This is the Amiga DigiView's raw storage format.  It consists of
nothing but three planes of data, one byte per pixel, followed by 12
bytes not associated with the image.  Because there is no size
information in a IP file, the width and height of the image must be
specified as the second and third arguments to LOAD.  A fourth
argument may be the words COLOR or MONO to specify the number of
planes.  COLOR is default.

The SAVE command is not supported for this format.

~RAW

One file per plane, one byte per pixel, nothing else.  The width and
height of the image must be specified as the second and third
arguments to LOAD.  A fourth argument may be either of the words
COLOR or MONO to specify the number of planes.  COLOR is default.

The file for plane one must have the .R8 extension, and the second
and third planes, if any, must have .G8 and .B8.

~CGA

Puts the CGA into standard 640 x 200 x 2 mode and displays two screen
pixels for each image pixel, covering an image area of 320 x 200.
Image data is halftoned while displaying, so it is quite slow.  No
color can be shown.

~EGA

Puts the EGA into standard 640 x 350 x 16 mode and displays one
screen pixel per image pixel.  8-color dithering is used to get an
approximation of the colors in the original image, so this mode is
rather slow.  Also note that this mode stretches the pixels
vertically more than any other mode.

~VGA1

Puts the VGA into standard 320 x 200 x 256-color mode and displays
one screen pixel for each image pixel.  Color-mapped images will
appear in full color; true-color and grayscale images will appear in
pseudo-gray which allows the VGA to display more than 64 shades but
with some slight tinges of color.

~VGA2

Puts the VGA into non-standard 360 x 480 x 256-color mode and
displays one screen pixel for every two image pixels, dropping every
other pixel horizontally so that an image area of 720 x 480 is
shown.  Color-mapped images will appear in full color; true-color and
grayscale images will appear in pseudo-gray which allows the VGA to
display more than 64 shades but with some slight tinges of color.

~SVGA1

Puts an extended VGA into 640 x 400 x 256-color mode.  This mode is
available on adapters from Ahead Systems, ATI, Chips & Technologies,
Everex, Paradise, Trident, Tseng Labs (including Orchid) and Headland
Technologies (Video 7).  Only 256k of video RAM is required for this
mode, but some adapters may require a multi-frequency monitor.

~SVGA2

Puts an extended VGA into 640 x 480 x 256-color mode.  This mode is
available on most non-IBM adapters (see SVGA1 mode description) and
requires 512k of video RAM and a multi-frequency monitor.

~SVGA3

Puts an extended VGA into 800 x 600 x 256-color mode.  This mode is
available on some adapters and requires 512k of video RAM and a high-
resolution multi-frequency monitor

~HICLR1

Puts an extended VGA with HiColor DAC (such as the STB PowerGraph Ergo)
into 640 x 480 x 32768-color mode.  Requires HiColor DAC, 1Mb of video
RAM and multi-frequency monitor.

~HICLR2

Puts an extended VGA with HiColor DAC (such as the STB PowerGraph Ergo)
into 800 x 600 x 32768-color mode.  Some HiColor boards and monitors may
not support this mode due to very close timing tolerances.

~PAINTJET

Images are printed to the HP PaintJet at 90 DPI.  Currently only
true-color images may be printed, so COLOR and UNMAP must be used to
print others.

~LASERJET

Currently only grayscale images may be printed to the HP LaserJet.
The variable DPI can be set to 75, 150, or 300 to determine the
output resolution.  If DPI is set to 300, the LaserJet must have more
than 1 MB of memory to print properly.

Each image pixel will generate four pixels on the printer, regardless
of DPI.  This is so that more accurate grayscale can be obtained.

~