NAME¶
ximage - RADIANCE picture display for X window system
SYNOPSIS¶
ximage [
=geometry ][
-di display ][
-c ncolors ][
-d ][
-b ][
-m ][
-g gamma ][
-f ][
-e
spec ][
-ospec ][
-t intvl ][
-s ]
picture
..
DESCRIPTION¶
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).
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 yields and appearance
of the scene on the display that closely matches what would be experienced in
the real world.
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¶
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.
The maximum of the three (RGB) channels is reported.
- l
- Display the photometrically-weighted 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, as adjusted by
the current exposure setting.
- 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. Pressing and holding the right mouse button is equivalent to
continuously pressing 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 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.)
- 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.)
- h
- Perform human expsoure compensation, as if ximage
were started with the -e human option. See the 'a' command above
regarding pixel weighting.
- 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.
X RESOURCES¶
radiance.gamma the default gamma correction value
ENVIRONMENT¶
DISPLAY_GAMMA the default gamma correction value
AUTHORS¶
Greg Ward
Anat Grynberg (Paris)
Philip Thompson (MIT)
SEE ALSO¶
aedimage(1),
normtiff(1),
pcond(1),
pfilt(1),
rpict(1),
rtrace(1),
rvu(1),
xglaresrc(1),
xshowtrace(1)