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ximage - RADIANCE driver for X window system
ximage [ =geometry ][ -di display ][ -c ncolors ][ -d ][ -b
][ -m ][ -g gamma ][ -f ][ -e +/-stops ][ -ospec ][ -s ]
picture ..
Ximage takes one or more RADIANCE picture files and displays
them on an X server. The -c option specifies the number of
colors to use (default fills color table). The -d option
turns off color dithering. The -b option displays the image
in black and white (greyscale). The -m option forces
monochrome output. The -g option specifies the exponent
used in gamma correction; the default value is 2.2. The -f
option stores a Pixmap on the server side for faster
refresh. This may not work with large images on some
servers. The -o option specifies a sequence of information
to print to the standard output for the `t' command (see
below). The -e option specifies an exposure compensation in
f-stops (powers of two). Only integer stops are allowed,
for efficiency.
The -s option tells ximage to display multiple pictures
sequentially, rather than all at once. If no picture is
given, input is read from stdin provided either the -b or -m
option is in effect, or the X server is capable of 24-bit
color. However, many of the commands given below will not
work.
Once a picture is displayed, the user may perform a number
of operations. Some of the operations make use of an area
of interest, defined by pressing the left mouse button and
dragging the cursor over a section of the image. Pressing
the button and immediately releasing it defines a single
point as the area of interest. A command is a single
character.
- q
- Quit picture. (Also Q or ^D.)
- <space>
- Redraw the area of interest.
- ^R
- Redraw the entire image.
<return> Display the radiance averaged over the area of
interest.
- l
- Display the luminance value in the area of
interest. This assumes that the image was
correctly computed in terms of luminance.
- c
- Display the color in the area of interest.
- p
- Display the x and y location of the cursor.
- i
- Identify identical pixels by assigning a random
color at the cursor position. This is useful for
displaying contours, especially when combined with
the -b option.
- t
- Print information about the pixel under the cursor
according to the string following the -o command
line option. The valid characters for this option
correspond roughly to the other ximage commands:
- o
- ray origin
- d
- ray direction
- v
- radiance value
- l
- luminance value
- p
- pixel position
The default output is "-ood", which prints the ray
origin and direction. This can be used as input
to rtrace(1) to get additional information about
the image (ie. pipe the output of ximage into
rtrace). Pressing the middle mouse button is
equivalent to typing the `t' key.
- =
- Adjust the exposure to the area of interest. A
crude adjustment is made immediately, and the
number of stops is printed while the colors are
resampled. After a few seconds to a minute, the
final image is redisplayed. If the area of
interest is already within 1/2 stop of the ideal,
no adjustment is made.
- @
- Same as `=' command, only the exposure is adjusted
to provide roughly the same visibility on screen
as a viewer would experience in the actual space.
The area selected should be a darker region in the
scene, representative of objects a real observer
might be trying to resolve. Like the `l' command,
this adjustment assumes that the image has been
correctly computed in terms of luminance.
- 0
- Reset the origin to the upper left corner of the
image. This command is used to restore the
original image position after using the shift or
control key with the mouse to relocate the image
within the frame (see below).
- f
- Switch on the fast redraw option (-f), loading the
image pixmap over to the server side. This
command is useful when network delays are causing
slow image refresh, and the user didn't notice it
until after ximage was started.
- F
- Switch off the fast redraw option. This frees up
some memory on the server, as well as the color
table for other windows.
In addition to the commands listed above, the control or
shift key may be held while the cursor is dragged to
reposition the image within the window.
radiance.gamma the default gamma correction value
- DISPLAY_GAMMA
- the default gamma correction value
Greg Ward
Anat Grynberg (Paris)
Philip Thompson (MIT)
aedimage(1), pfilt(1), rpict(1), rtrace(1), rview(1),
xglaresrc(1), xshowtrace(1)
Header and Footer
XIMAGE(1) RADIANCE (12/13/95) XIMAGE(1)
Page 1 (printed 7/17/96)
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