xview

XLI(1)                       General Commands Manual                      XLI(1)



NAME
       xli, xsetbg, xview - load images into an X11 window or onto the root
       window

SYNOPSIS
       xli [global_options] {[image_options] image ...}
       xli [global_options] [image_options] stdin < image

DESCRIPTION
       xli displays images in an X11 window or loads them onto the root window.
       See the IMAGE TYPES section below for supported image types.

       If the filename stdin is given, xli will read the image from standard
       input.

       If the destination display cannot support the number of colors in the
       image, the image will be dithered (monochrome destination) or have its
       colormap reduced (color destination) as appropriate.  This can also be
       done forcibly with the -halftone, -dither, and -colors options.

       A variety of image manipulations can be specified, including gamma
       correction, brightening, clipping, dithering, depth-reduction, rotation,
       and zooming.  Most of these manipulations have simple implementations;
       speed was opted for above accuracy.

       If you are viewing a large image in a window, the initial window will be
       at most 90% of the size of the display unless the window manager does not
       correctly handle window size requests or if you've used the -fullscreen
       or -fillscreen options.  You may move the image around in the window by
       dragging with the first mouse button.  The cursor will indicate which
       directions you may drag, if any.

       When the keyboard focus is in the window you can:
       Type 'q' or '^C' to exit xli.
       Type space, 'n' or 'f' to move to the next image in the list.
       Type 'b' or 'p' to move to the previous image in the list.
       Type . to reload the image.
       Type l to rotate the image anti-clockwise.
       Type r to rotate the image clockwise.
       Type 0 to set the images assumed gamma to your display gamma
              (usually darkens images)
       Type 1 to set the images assumed gamma to 1.0
              (usually lightens images)
       Type 5-2 to lighten the image (5 in small steps, up to 2 in large steps)
       Type 6-9 to darken the image (6 in small steps, up to 9 in large steps)

       A wide variety of common image manipulations can be done by mixing and
       matching the available options.  See the section entitled HINTS FOR GOOD
       IMAGE DISPLAYS for some ideas.

       Xsetbg is equivalent to xli -onroot -quiet and xview is equivalent to xli
       -view -verbose.

RESOURCE CLASS
       xli uses the resource class name _XSETROOT_Id for window managers which
       need this resource set.

GLOBAL OPTIONS
       The following options affect the global operation of xli.  They may be
       specified anywhere on the command line.

       -default
              Set the root background to the default root weave.  This is the
              same as xsetroot with no arguments.

       -debug Talk to the X server in synchronous mode.  This is useful for
              debugging.  If an X error is seen while in this mode, a core will
              be dumped.

       -dumpcore
              Signals will not be trapped, and instead a coredump will occur.

       -display display_name
              X11 display name to send the image(s) to.

       -dispgamma Display_gamma
              Specify the gamma correction value appropriate for the display
              device.  This overides the value read from the environment
              variable DISPLAY_GAMMA, or the default value of 2.2, which is
              approximately correct for many displays. A value of between 1.6
              and 2.8 is reasonable. If individual images are too bright or
              dark, use the -gamma option.

       There is an image provided with xli called 'chkgamma.jpg' that lets you
       set the display gamma reasonably accurately.  This file contains two
       grayscale ramps. The ramps are chosen to look linear to the human eye,
       one using continuous tones, and the other using dithering.  When the
       display gamma is correct, then the two ramps should look symmetrical, and
       the point at which they look equally bright should be almost exactly half
       way from the top to the bottom. (To find this point it helps if you move
       away a little from the screen, and de-focus your eyes a bit.)

       If the equal brightness point is above center increase the gamma, and
       decrease it if it is below the center. The value will usually be around
       2.2 Once you've got it right, you can set the DISPLAY_GAMMA environment
       variable in your .profile

       -fillscreen
              Use the whole screen for displaying an image. The image will be
              zoomed so that it just fits the size of the screen. If -onroot is
              also specified, it will be zoomed to completely fill the screen.

       -fit   Force image to use the default visual and colormap.  This is
              useful if you do not want technicolor effects when the colormap
              focus is inside the image window, but it may reduce the quality of
              the displayed image.  This is on by default if -onroot or
              -windowid is specified.

       -fork  Fork xli.  This causes xli to disassociate itself from the shell.
              This option automatically turns on -quiet.

       -fullscreen
              Use the whole screen for displaying an image. The image will be
              surrounded by a border if it is smaller than the screen. If
              -onroot is also specified, the image will be zoomed so that it
              just fits the size of the screen.

       -geometry WxH[{+-X}{+-}Y]
              This sets the size of the window onto which the images are loaded
              to a different value than the size of the image.  When viewing an
              image in a window, this can be used to set the size and position
              of the viewing window.  If the size is not specified in the
              geometry, (or is set to 0), then the size will be chosen to be
              small enough to able to fit the window in the screen (as usual).

       -goto image_name
              When the end of the list of images is reached, go to image
              image_name.  This is useful for generating looped slideshows.  If
              more than one image of the same name as the target exists on the
              argument list, the first in the argument list is used.

       -help [option ...]
              Give information on an option or list of options.  If no option is
              given, a simple interactive help facility is invoked.

       -identify
              Identify the supplied images rather than display them.

       -install
              Forcibly install the images colormap when the window is focused.
              This violates ICCCM standards and only exists to allow operation
              with naive window managers.  Use this option only if your window
              manager does not install colormaps properly.

       -list  List the images which are along the image path.

       -onroot
              Load image(s) onto the root window instead of viewing in a window.
              This option automatically sets the -fit option.  This is the
              opposite of -view.  XSetbg has this option set by default.  If
              used in conjunction with -fullscreen, the image will be zoomed to
              just fit. If used with -fillscreen, the image will be zoomed to
              completely fill the screen. -border, -at, and -center also affect
              the results.

       -path  Displays the image path and image suffixes which will be used when
              looking for images.  These are loaded from ~/.xlirc and optionally
              from a system wide file (normally /usr/lib/xlirc).

       -pixmap
              Force the use of a pixmap as backing-store.  This is provided for
              servers where backing-store is broken (such as some versions of
              the AIXWindows server).  It may improve scrolling performance on
              servers which provide backing-store.

       -private
              Force the use of a private colormap.  Normally colors are
              allocated shared unless there are not enough colors available.

       -quiet Forces xli and xview to be quiet.  This is the default for xsetbg,
              but the others like to whistle.

       -supported
              List the supported image types.

       -verbose
              Causes xli to be talkative, telling you what kind of image it's
              playing with and any special processing that it has to do.  This
              is the default for xview and xli.

       -version
              Print the version number and patchlevel of this version of xli.

       -view  View image(s) in a window.  This is the opposite of -onroot and
              the default for xview and xli.

       -visual visual_name
              Force the use of a specific visual type to display an image.
              Normally xli tries to pick the best available image for a
              particular image type.  The available visual types are:
              DirectColor, TrueColor, PseudoColor, StaticColor, GrayScale, and
              StaticGray.  Nonconflicting names may be abbreviated and case is
              ignored.

       -windowid hex_window_id
              Sets the background pixmap of a particular window ID.  The
              argument must be in hexadecimal and must be preceded by "0x" (eg
              -windowid 0x40000b.  This is intended for setting the background
              pixmap of some servers which use untagged virtual roots (eg HP-
              VUE), but can have other interesting applications.

PERSISTENT IMAGE OPTIONS
       The following options may precede each image.  They take effect from the
       next image, and continue until overridden or canceled with -newoptions.

       -border color
              This sets the background portion of the window or clipped image
              which is not covered by any images to be color.

       -brighten percentage
              Specify a percentage multiplier for a color images colormap.  A
              value of more than 100 will brighten an image, one of less than
              100 will darken it.

       -colors n
              Specify the maximum number of colors to use in the image.  This is
              a way to forcibly reduce the depth of an image.

       -cdither

       -colordither
              Dither the image with a Floyd-Steinberg dither if the number of
              colors is reduced.  This will be slow, but will give a better
              looking result with a restricted color set. -cdither and
              -colordither are equivalent.

       -delay secs
              Sets xli to automatically advance to the following image, secs
              seconds after the next image file is displayed.

       -dither
              Dither a color image to monochrome using a Floyd-Steinberg
              dithering algorithm.  This happens by default when viewing color
              images on a monochrome display.  This is slower than -halftone and
              affects the image accuracy but usually looks much better.

       -gamma Image_gamma
              Specify the gamma of the display the image was intended to be
              displayed on.  Images seem to come in two flavors: 1) linear color
              images, produced by ray tracers, scanners etc. These sort of
              images generally look too dark when displayed directly to a CRT
              display. 2) Images that have been processed to look right on a
              typical CRT display without any sort of processing. These images
              have been 'gamma corrected'. By default, xli assumes that 8 bit
              images have been gamma corrected and need no other processing. 24
              bit images are assumed to be linear.  If a linear image is
              displayed as if it is gamma corrected it will look too dark, and a
              gamma value of 1.0 should be specified, so that xli can correct
              the image for the CRT display device. If a gamma corrected image
              is displayed as if it were a linear image, then it will look too
              light, and a gamma value of (approximately) 2.2 should be
              specified for that image.  Some formats (RLE) allow the image
              gamma to be embedded as a comment in the file itself, and the
              -gamma option allows overriding of the file comment.  In general,
              values smaller than 2.2 will lighten the image, and values greater
              than 2.2 will darken the image.  In general this will work better
              than the -brighten option.

       -gray  Convert an image to grayscale.  This is very useful when
              displaying colorful images on servers with limited color
              capability.  The optional spelling -grey may also be used.

       -idelay secs
              Set the delay to be used for this image to secs seconds (see
              -delay).  If -delay was specified, this overrides it.  If it was
              not specified, this sets the automatic advance delay for this
              image while others will wait for the user to advance them.

       -smooth
              Smooth a color image.  This reduces blockiness after zooming an
              image up.  If used on a monochrome image, nothing happens.  This
              option can take awhile to perform, especially on large images.
              You may specify more than one -smooth option per image, causing
              multiple iterations of the smoothing algorithm.

       -title window_title
              Set the titlebar of the window used to display the image.  This
              will overide any title that is read from the image file. The title
              will also be used for the icon name.

       -xpm color_context_key
              Select the prefered xpm colour map. XPM files may contain more
              than one color mapping, each mapping being appropriate for a
              particular visual.  Normally xli will select an apropriate color
              mapping from that supported by the XPM file by checking on the
              default X visual class and depth.  This option allows the user to
              overide this choice.  Legal values of  color_context_key are: m,
              g4, g and c.  m = mono, g4 = 4 level gray, g = gray, c = color ).

       -xzoom percentage
              Zoom the X axis of an image by percentage.  A number greater than
              100 will expand the image, one smaller will compress it.  A zero
              value will be ignored.  This option, and the related -yzoom are
              useful for correcting the aspect ratio of images to be displayed.

       -yzoom percentage
              Zoom the Y axis of an image by percentage.  See -xzoom for more
              information.

       -zoom percentage
              Zoom both the X and Y axes by percentage.  See -xzoom for more
              information.  Technically the percentage actually zoomed is the
              square of the number supplied since the zoom is to both axes, but
              I opted for consistency instead of accuracy.

       -newoptions
              Reset options that propagate.  The -bright, -colors, -colordither,
              -delay, -dither, -gamma, -gray, -normalize, -smooth, -xzoom,
              -yzoom, and -zoom options normally propagate to all following
              images.

LOCAL IMAGE OPTIONS
       The following options may precede each image.  These options are local to
       the image they precede.

       -at X,Y
              Indicates coordinates to load the image at X,Y on the base image.
              If this is an option to the first image, and the -onroot option is
              specified, the image will be loaded at the given location on the
              display background.

       -background color
              Use color as the background color instead of the default (usually
              white but this depends on the image type) if you are transferring
              a monochrome image to a color display.

       -center
              Center the image on the base image loaded.  If this is an option
              to the first image, and the -onroot option is specified, the image
              will be centered on the display background.

       -clip X,Y,W,H
              Clip the image before loading it.  X and Y define the upper-left
              corner of the clip area, and W and H define the extents of the
              area.  A zero value for W or H will be interpreted as the
              remainder of the image.  Note that X and Y may be negative, and
              that W and H may be larger than the image. This causes a border to
              be placed around the image. The border color may be set with the
              -border option.

       -expand
              Forces the image (after all other optional processing) to be
              expanded into a True Color (24 bit) image. This is useful on
              systems which support 24 bit color, but where xli might choose to
              load a bitmap or 8 bit image into one of the other smaller depth
              visuals supported on your system.

       -foreground color
              Use color as the foreground color instead of black if you are
              transferring a monochrome image to a color display.  This can also
              be used to invert the foreground and background colors of a
              monochrome image.

       -halftone
              Force halftone dithering of a color image when displaying on a
              monochrome display.  This option is ignored on monochrome images.
              This dithering algorithm blows an image up by sixteen times; if
              you don't like this, the -dither option will not blow the image up
              but will take longer to process and will be less accurate.

       -invert
              Inverts a monochrome image.  This is shorthand for -foreground
              white -background black.

       -merge Merge this image onto the base image after local processing.  The
              base image is considered to be the first image specified or the
              last image that was not preceded by -merge.  If used in
              conjunction with -at and -clip, very complex images can be built
              up.  Note that the final image will be the size of the first
              image, and that subsequent merged images overlay previous images.
              The final image size can be altered by using the -clip option on
              the base image to make it bigger or smaller.  This option is on by
              default for all images if the -onroot or -windowid options are
              specified.

       -name image_name
              Force the next argument to be treated as an image name.  This is
              useful if the name of the image is -dither, for instance.

       -normalize
              Normalize a color image.

       -rotate degrees
              Rotate the image by degrees clockwise.  The number must be a
              multiple of 90.

EXAMPLES
       To load the rasterfile "my.image" onto the background and replicate it to
       fill the entire background:

            xli -onroot my.image

       To load a monochrome image "my.image" onto the background, using red as
       the foreground color, replicate the image, and overlay "another.image"
       onto it at coordinate (10,10):

            xli -foreground red my.image -at 10,10 another.image

       To center the rectangular region from 10 to 110 along the X axis and from
       10 to the height of the image along the Y axis:

            xli -center -clip 10,10,100,0 my.image

       To double the size of an image:

            xli -zoom 200 my.image

       To halve the size of an image:

            xli -zoom 50 my.image

       To brighten a dark image:

            xli -brighten 150 my.image

       To darken a bright image:

            xli -brighten 50 my.image

HINTS FOR GOOD IMAGE DISPLAYS
       Since images are likely to come from a variety of sources, they may be in
       a variety of aspect ratios which may not be supported by your display.
       The -xzoom and -yzoom options can be used to change the aspect ratio of
       an image before display.  If you use these options, it is recommended
       that you increase the size of one of the dimensions instead of shrinking
       the other, since shrinking looses detail.  For instance, many GIF and G3
       FAX images have an X:Y ratio of about 2:1.  You can correct this for
       viewing on a 1:1 display with either -xzoom 50 or -yzoom 200 (reduce X
       axis to 50% of its size and expand Y axis to 200% of its size,
       respectively) but the latter should be used so no detail is lost in the
       conversion.

       When zooming color images up you can reduce blockiness with -smooth.  For
       zooms of 300% or more, I recommend two smoothing passes (although this
       can take awhile to do on slow machines).  There will be a noticeable
       improvement in the image.

       You can perform image processing on a small portion of an image by
       loading the image more than once and using the -merge, -at and -clip
       options.  Load the image, then merge it with a clipped, processed version
       of itself.  To brighten a 100x100 rectangular portion of an image located
       at (50,50), for instance, you could type:

            xli my.image -merge -at 50,50 -clip 50,50,100,100 -brighten 150
       my.image

       If you're using a display with a small colormap to display colorful
       images, try using the -gray option to convert to grayscale.

XLITO
       xlito (XLoadImageTrailingOptions) is a separate utility that provides a
       file format independent way of marking image files with the appropriate
       options to display correctly.  It does this by appending to file a string
       specified by the user, marked with some magic numbers so that this string
       can be extracted by a program that knows where to look. Since almost all
       image files have some sort of image size specifier, the programs that
       load or manipulate these files do not look beyond the point at which they
       have read the image, so trailing information can safely be appended to
       the file. If appending this information causes trouble with other
       utilities, it can simply be deleted.

       xli will recognize these trailing options at the end of the image files,
       and will treat the embedded string as if it were a sequence of command
       line IMAGE OPTIONS. Any GLOBAL OPTIONS will be ignored, and the IMAGE
       OPTIONS are never propagated to other images.

       Trailing options can be examined with:

            xlito image_file ...

       Changed or added with:

            xlito -c "string of options" image_file

       And deleted with:

            xlito -d image_file ...

       For example, if you have a gif file fred.gif which is too dark and is the
       wrong aspect ratio, then it may need to be viewed with:

            xli -yzoom 130 -gamma 1.0 fred.gif

       to get it to look OK. These options can then be appended to the file by:

            xlito -c "-yzoom 130 -gamma 1.0" fred.gif

       and from then on xli will get the appropriate options from the image file
       itself.  See the  xlito manual entry for more details about this utility.


PATHS AND EXTENSIONS
       The file ~/.xlirc (and optionally a system-wide file) defines the path
       and default extensions that xli will use when looking for images.  This
       file can have two statements: "path=" and "extension=" (the equals signs
       must follow the word with no spaces between).  Everything following the
       "path=" keyword will be prepended to the supplied image name if the
       supplied name does not specify an existing file.  The paths will be
       searched in the order they are specified.  Everything following the
       "extension=" keyword will be appended to the supplied image name if the
       supplied name does not specify an existing file.  As with paths, these
       extensions will be searched in the order they are given.  Comments are
       any portion of a line following a hash-mark (#).

       The following is a sample ~/.xlirc file:

         # paths to look for images in
         path= /usr/local/images
               /home/usr1/guest/madd/images
               /usr/include/X11/bitmaps

         # default extensions for images; .Z is automatic; scanned in order
         extension= .csun .msun .sun .face .xbm .bm

       Versions of xli prior to version 01, patchlevel 03 would load the system-
       wide file (if any), followed by the user's file.  This behavior made it
       difficult for the user to configure her environment if she didn't want
       the default.  Newer versions will ignore the system-wide file if a
       personal configuration file exists.

IMAGE TYPES
       xli currently supports the following image types:

         CMU Window Manager raster files
         Faces Project images
         Fuzzy Bitmap (.fbm) images
         GEM bit images
         GIF images (Including GIF89a compatibility)
         G3 FAX images
         JFIF style jpeg images
         McIDAS areafiles
         MacPaint images
         Windows, OS/2 RLE Image
         Monochrome PC Paintbrush (.pcx) images
         Photograph on CD Image
         Portable Bitmap (.pbm, .pgm, .ppm) images
         Sun monochrome rasterfiles
         Sun color RGB rasterfiles
         Targa (.tga) files
         Utah Raster Toolkit (.rle) files
         X pixmap (.xpm) files (Version 1, 2C and 3)
         X10 bitmap files
         X11 bitmap files
         X Window Dump (except TrueColor and DirectColor)

       Normal, compact, and raw PBM images are supported.  Both standard and
       run-length encoded Sun rasterfiles are supported.  Any image whose name
       ends in .Z is assumed to be a compressed image and will be filtered
       through "uncompress". If HAVE_GUNZIP is defined in the Makefile.std make
       file, then any image whose name ends in

       Any file that looks like a uuencoded file will be decoded automatically.

AUTHORS
       The original Author is:
       Jim Frost
       Saber Software
       jimf@saber.com

       Version 1.16 of xli is derived from xloadimage 3.01 has been brought to
       you by:
       Graeme Gill
       graeme@labtam.oz.au

       Version 1.17 of xli is derived from xli 1.16 by
       smar@reptiles.org

       For a more-or-less complete list of other contributors (there are a lot
       of them), please see the README file enclosed with the distribution.

FILES
            xli                      - the image loader and viewer
            xsetbg                  - pseudonym which quietly sets the background
            xview                   - pseudonym which views in a window
            xlito                   - the trailing options utility
            /usr/lib/X11/Xli        - default system-wide configuration file
            ~/.xlirc                - user's personal configuration file

COPYRIGHT
       Copyright (c) 1989, 1990, 1991, 1992, 1993 Jim Frost, Graeme Gill and
       others.

       Xli is copywritten material with a very loose copyright allowing
       unlimited modification and distribution if the copyright notices are left
       intact.  Various portions are copywritten by various people, but all use
       a modification of the MIT copyright notice.  Please check the source for
       complete copyright information.  The intent is to keep the source free,
       not to stifle its distribution, so please write to me if you have any
       questions.

BUGS
       Zooming dithered images, especially downwards, is UGLY.

       Images can come in a variety of aspect ratios.  Xli cannot detect what
       aspect ratio the particular image being loaded has, nor the aspect ratio
       of the destination display, so images with differing aspect ratios from
       the destination display will appear distorted.  The solution to this is
       to use xlito to append the appropriate options to the image file. See
       HINTS FOR GOOD IMAGE DISPLAYS and XLITO for more information.

       The GIF format allows more than one image to be stored in a single GIF
       file, but xli will only display the first.

       One of the pseudonyms for xli, xview, is the same name as Sun uses for
       their SunView-under-X package.  This will be confusing if you're one of
       those poor souls who has to use Sun's XView.

       Some window managers do not correctly handle window size requests.  In
       particular, many versions of the twm window manager use the MaxSize hint
       instead of the PSize hint, causing images which are larger than the
       screen to display in a window larger than the screen, something which is
       normally avoided.  Some versions of twm also ignore the MaxSize
       argument's real function, to limit the maximum size of the window, and
       allow the window to be resized larger than the image.  If this happens,
       xli merely places the image in the upper-left corner of the window and
       uses the zero-value'ed pixel for any space which is not covered by the
       image.  This behavior is less-than-graceful but so are window managers
       which are cruel enough to ignore such details.

       The order in which operations are performed on an image is independent of
       the order in which they were specified on the command line.  Wherever
       possible I tried to order operations in such a way as to look the best
       possible (zooming before dithering, for instance) or to increase speed
       (zooming downward before compressing, for instance).

       Display Gamma should setable in the ~/.xlirc file.

       Embedded trailing options overide the command line Image Options. Command
       line options should really overide trailing options.



                                   27 Jul 1994                            XLI(1)