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ximage (1)
NAME
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ximage - RADIANCE driver for X window system |
SYNOPSIS
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ximage [ =geometry ][ -di display ][
-c ncolors ][ -d ][ -b ][ -m ][
-g gamma ][ -f ][ -e spec ][
-ospec ][ -t intvl ][ -s ]
picture .. |
DESCRIPTION
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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 -t option
specifies a minimum interval (in milliseconds) between
successive ray outputs in mouse tracking mode (right button
pressed). |
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The -e option specifies an exposure compensation in
f-stops (powers of two). Only integer stops are allowed, for
efficiency. If the special word, auto is given
instead of a number of stops, then ximage performs an
automatic exposure adjustment similar to pcond(1),
compressing the dynamic range of the image to fit within the
dynamic range of the display. If the special word,
human is given instead, then ximage performs
an exposure adjustment similar to pcond with the
-s and -c options, which compensate for human
contrast and color sensitivity at the corresponding scene
luminance levels. This option yeilds and appearance of the
scene on the display that closely matches what would be
experienced in the real world. |
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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. |
COMMANDS
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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. |
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q Quit picture. (Also Q or ^D.) |
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Redraw the area of interest. |
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^R Redraw the entire image. |
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Display the radiance averaged over the area of
interest. |
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l Display the luminance value in the area of
interest. This assumes that the image was correctly computed
in terms of luminance. |
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c Display the color in the area of
interest. |
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p Display the x and y location of the
cursor. |
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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. |
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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: |
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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. Pressing and
holding the right mouse button is equivalent to continuously
pressing the 't' key. |
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= 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. |
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@ Same as '=' command, only the exposure is adjusted
to provide roughly the same visibility for the selected
region on screen as a viewer would experience in the actual
space. Like the 'l' command, this adjustment assumes that
the image has been correctly computed in terms of luminance.
(See also the 'h' command, below.) |
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a Perform automatic exposure compensation, as if
ximage were started with the -e auto option.
If a rectangular area has been selected, the pixels in this
region will be emphasized in the histogram, offering this
area exposure preference. (Each pixel within the rectangle
will be weighted as 21 outside pixels.) |
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h Perform human expsoure compensation, as if
ximage were started with the -e human option.
See the 'a' command above regarding pixel
weighting. |
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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). |
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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. |
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F Switch off the fast redraw option. This frees up
some memory on the server, as well as the color table for
other windows. |
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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. |
X RESOURCES
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radiance.gamma the default gamma correction
value |
ENVIRONMENT
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DISPLAY_GAMMA the default gamma correction
value |
AUTHORS
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Greg Ward
Anat Grynberg (Paris)
Philip Thompson (MIT) |
SEE ALSO
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