.\" Copyright (c) 1989, University of Utah
.TH GET4D 1 "June 20, 1989" 1
.UC 4 
.SH NAME
get4d \- get RLE images to a Silicon Graphics Iris/4D display
.SH SYNOPSIS
.B get4d
[
.B \-D
] [
.B \-f
] [
.B \-{GS}
] [
.B \-g
.I "disp_gamma"
] [
.B \-{iI}
.I "image_gamma"
] [
.B \-n
] [
.B \-p
.I "xpos ypos"
] [
.B \-s
.I "xsize ysize"
] [
.B \-w
] [ 
.I infile
]

.SH DESCRIPTION
This program displays an
.IR RLE (5)
file on a
.I Silicon Graphics Iris/4D
display or
.I IBM RS6000
with the GL library.

The default behavior is to display the image in RGB color.  An option is
provided to force black and white display.  There is currently no support in
.I get4D
for non-24-bit color (lookup table modes), but the
.I getmex (1)
program should work on 8-bit 4D's which cannot do RGB display.

The GT graphics fast pixel access routines are used by default on 4D/GT and
GTX machines, and Personal Irises.  The
.B \-G
option is provided to force this mode, if the string returned by the
.IR gversion (3g)
function changes, or is different on future 4D's.

The penalty of GT mode is not being able to resize or pan the window, but
redisplay is so fast that there is no need to do so.  You can also go into
"slow mode" on GT machines by giving the
.B \-S
flag.  Slow mode allows resizing the window and panning with the mouse.
.SH OPTIONS
.TP
.B \fB\-p\ \fIxpos\ ypos\fR
Position of the lower left corner of the window.
.TP
.B \fB\-s\ \fIxsize\ ysize\fR
Initial size of the window (slow mode only.)
.TP
.B \-f
Normally,
.I get4d
will fork itself after putting the image on the screen, so that the
parent process may return the shell, leaving an "invisible" child to
keep the image refreshed.  If 
.B \-f
is specified, get4d will remain attached to the shell, whence it may be killed
with an interrupt signal.  In either case the window manager "quit" menu
button can be used to kill 
.I get4d.
.TP
.BI \-g " display_gamma"
Specify the gamma of the display monitor.  If this flag is not specified,
.I get4d
looks in the user's home directory for a .gamma file.  This file is 
produced by the
.IR gamma (1g)
SGI command (This is not done on the IBM R6000).  The value in the .gamma
file is used to determine the gamma of the display by calculating (2.4 /
.I gamma_value
) and using that as the 
.I disp_gamma.
.TP
.BI \-i " image_gamma"
Specify the gamma (contrast) of the image.  A low contrast image,
suited for direct display without compensation on a high contrast
monitor (as most monitors are) will have a gamma of less than one.
The default image gamma is 1.0.  Image gamma may also be specified by
a picture comment in the
.I RLE (5)
file of the form
.BI image_gamma= gamma.
The command line argument will override the value in the file if specified.
.TP
.BI \-I " image_gamma"
An alternate method of specifying the image gamma, the number
following
.B \-I
is the gamma of the display for which the image was originally
computed (and is therefore 1.0 divided by the actual gamma of the
image).  Image display gamma may also be specified by
a picture comment in the
.I RLE (5)
file of the form
.BI display_gamma= gamma.
The command line argument will override the value in the file if specified.
.TP
.B \-n
Do not draw a window border.
.TP
.B \-w
This flag forces
.I get4d
to produce a gray scale dithered image instead of a color image.
Color input will be transformed to black and white via the
.I NTSC Y
transform.
.TP
.B \-D
"Debug mode".  The operations in the input
.IR RLE (5)
file will be printed as they are read.
.TP
.I file
Name of the
.IR RLE (5)
file to display.  If not specified, the image will be read from the
standard input.
.LP
In "slow mode" You can "pan" a small window around in an image by
clicking the
.I left mouse button
in the image.  The position in the image
under the cursor will jump to the center of the window.  The
.I F9 key
or
.I Alt keys
reset the view to position the center of the image in the center of the
window.  Furthermore,
.I control-F9 (or control-Alt)
saves the current view, and
.I shift-F9 (or shift-Alt)
restores it.
.SH NOTE
If you have a shaded image that looks "too dark", it is probably because the
gamma is not set on the display.  (The default gamma is 1, which assumes that
gamma compensation will be done once and for all by programs producing images.)
.I gamma 2
is better when the image producing program does not do the gamma correction.
You may want to put a gamma command in your .login file.
.SH SEE ALSO
.IR getmex (1), 
.IR urt (1),
.IR gversion (3g), 
.IR gamma (1g),
.IR RLE (5).
.SH AUTHOR
Russ Fish, University of Utah.
Based on getX, by Spencer W. Thomas.