XIMAGE(1)                                                            XIMAGE(1)



NNAAMMEE
       ximage - RADIANCE picture display for X window system

SSYYNNOOPPSSIISS
       xxiimmaaggee [ ==ggeeoommeettrryy ][ --ddii ddiissppllaayy ][ --cc nnccoolloorrss ][ --dd ][ --bb ][ --mm ][ --gg
       ggaammmmaa ][ --ff ][ --ee ssppeecc ][ --oo_s_p_e_c ][ --tt iinnttvvll ][ --ss ] ppiiccttuurree ....

DDEESSCCRRIIPPTTIIOONN
       _X_i_m_a_g_e 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,  _a_u_t_o is given instead of a number of stops, then _x_i_m_a_g_e performs
       an automatic exposure adjustment similar to _p_c_o_n_d_(_1_)_,  compressing  the
       dynamic  range of the image to fit within the dynamic range of the dis-
       play.  If the special word, _h_u_m_a_n is given instead,  then  _x_i_m_a_g_e  per-
       forms  an  exposure  adjustment  similar  to  _p_c_o_n_d  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.

       The  _-_s  option tells _x_i_m_a_g_e to display multiple pictures sequentially,
       rather than all at once.  If no _p_i_c_t_u_r_e 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.

CCOOMMMMAANNDDSS
       Once  a  picture  is displayed, the user may perform a number of opera-
       tions.  Some of the operations make use of an area of interest, defined
       by  pressing  the left mouse button and dragging the cursor over a sec-
       tion 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.

       qq         Quit picture.  (Also Q or ^D.)

       <<ssppaaccee>>   Redraw the area of interest.

       ^^RR        Redraw the entire image.

       <<rreettuurrnn>>  Display the radiance averaged over the area of interest.  The
                 maximum of the three (RGB) channels is reported.

       ll         Display  the  photometrically-weighted luminance value in the
                 area of interest.  This assumes that the image was  correctly
                 computed in terms of luminance.

       cc         Display the color in the area of interest, as adjusted by the
                 current exposure setting.

       pp         Display the x and y location of the cursor.

       ii         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.

       tt         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 _x_i_m_a_g_e 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 adjust-
                 ment 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 adjust-
                 ment 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.)

       aa         Perform  automatic  exposure  compensation, as if _x_i_m_a_g_e were
                 started with the _-_e _a_u_t_o 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 out-
                 side pixels.)

       hh         Perform  human  expsoure  compensation,  as  if  _x_i_m_a_g_e  were
                 started  with the _-_e _h_u_m_a_n option.  See the 'a' command above
                 regarding pixel weighting.

       00         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).

       ff         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 _x_i_m_a_g_e was started.

       FF         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.

XX RREESSOOUURRCCEESS
       radiance.gamma the default gamma correction value

EENNVVIIRROONNMMEENNTT
       DISPLAY_GAMMA       the default gamma correction value

AAUUTTHHOORRSS
       Greg Ward
       Anat Grynberg (Paris)
       Philip Thompson (MIT)

SSEEEE AALLSSOO
       aedimage(1),  normtiff(1),  pcond(1),  pfilt(1),  rpict(1),  rtrace(1),
       rvu(1), xglaresrc(1), xshowtrace(1)



RADIANCE                           10/27/98                          XIMAGE(1)
