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get4d - get RLE images to a Silicon Graphics Iris/4D display
get4d
[ -D ] [ -f ] [ -{GS} ] [ -g disp_gamma ] [ -{iI} image_gamma ] [ -n ] [ -p xpos
ypos ] [ -s xsize ysize ] [ -w ] [ infile ]
This program displays
an RLE(5)
file on a Silicon Graphics Iris/4D display or 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 get4D for non-24-bit color (lookup table modes), but the 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 -G option is provided to force this mode,
if the string returned by the 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 -S flag. Slow
mode allows resizing the window and panning with the mouse.
- -p xpos ypos
- Position of the lower left corner of the window.
- -s xsize ysize
- Initial size
of the window (slow mode only.)
- -f
- Normally, 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
-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 get4d.
- -g display_gamma
- Specify the gamma
of the display monitor. If this flag is not specified, get4d looks in the
user's home directory for a .gamma file. This file is produced by the 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 /
gamma_value ) and using that as the disp_gamma.
- -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 RLE (5)
file
of the form image_gamma=gamma. The command line argument will override the
value in the file if specified.
- -I image_gamma
- An alternate method of specifying
the image gamma, the number following -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 RLE (5)
file of the form display_gamma=gamma.
The command line argument will override the value in the file if specified.
- -n
- Do not draw a window border.
- -w
- This flag forces get4d to produce a gray
scale dithered image instead of a color image. Color input will be transformed
to black and white via the NTSC Y transform.
- -D
- "Debug mode". The operations
in the input RLE(5)
file will be printed as they are read.
- file
- Name of
the RLE(5)
file to display. If not specified, the image will be read from
the standard input.
In "slow mode" You can "pan" a small window around in
an image by clicking the left mouse button in the image. The position in
the image under the cursor will jump to the center of the window. The F9
key or Alt keys reset the view to position the center of the image in the
center of the window. Furthermore, control-F9 (or control-Alt) saves the
current view, and shift-F9 (or shift-Alt) restores it.
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.) 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.
getmex(1)
,
urt(1)
, gversion(3g)
, gamma(1g)
, RLE(5)
.
Russ Fish, University of
Utah. Based on getX, by Spencer W. Thomas.
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