XGRABSC

NAME

SYNOPSIS

DESCRIPTION

Command line options also allow reduction of colormaps, halftoning and dithering of color images, and direct mapping of color images to monochrome.

Options must be seperated with spaces or tabs. They may be preceded with a dash, but this optional and provided for Un*x addicts. Many may also be prefixed with 'no', or an additional dash, to turn them off.

The default output format is gray-scale non-encapsulated Postscript, with image compression (if image compression significantly reduces the amount of output).

If you desire an output format not produced by xgrabsc, try using the PBM package by Jef Poskanzer to convert xgrabsc to that format. PBM can read xgrabsc's XWD output and convert it to a lot of different formats.  

GENERAL OPTIONS

-d displayName or -display displayName

Use an alternate display. If no display is specified on the command line, xgrabsc looks for the environment variable DISPLAY for the name of the display and screen to grab from. Note that you must have permission to access the display on another computer.

-bell

The display's bell is normally rung while the screen is being accessed. This turns the bell on or off (-nobell will turn it off).

-grab

Enable server grabs. Normally xgrabsc will "grab" the server so that the screen is frozen while a rectangle is selected and the image is extracted. If the screen is not frozen, rubber-banding may cause video droppings on portions of the screen that are changing. Use -nograb to turn off server grabs.

-o output-file or -output output-file

Write output to output-file instead of standard output. The output-file name, minus directory and extension, is used as the internal name for the image in formats supporting image names. Postscript, xwd, pixmap and bitmap formats all support image names.

-s seconds or -sleep seconds

Sleep for seconds seconds before commencing operation. This should be used if you need some time to get the target image ready.

-post seconds

Sleep for seconds seconds after window/rectangle selection. This is commonly used to pop up menus after a window has been selected but before xgrabsc takes its snapshot.

-verbose

Display processing information on standard error output (stderr).

SELECTION OPTIONS

-id window ID

Dump the window with the given ID.

-key

Select the window under the mouse when the Control key is pressed. This option is normally used in getting images of menus. Pop up the menu, optionally move the pointer to the window containing the menu, and strike the Control key to begin the dump.

-root

Dump the entire screen (root window).

-stretch

Use rubber-band rectangle to select region to grab. This is the default.

-click

Wait for a click on a window and dump the selected window.

-coords widthxheight+x+y

Selects the given area of the screen, without mouse or keyboard interaction. Use this if you need to grab the same area of the screen over and over again.

IMAGE PROCESSING OPTIONS

-nobdrs or -noborders

Remove window-manager borders from window images. This option applies only to selection by ID (-id) or xwd-style selection (-click).

-bdrs or -borders

Include window-manager borders in window images. This option applies only to selection by ID (-id) or xwd-style selection (-click). Use -nobdrs or -noborders to turn it off.

-b percent or -brighten percent

brighten or darken the image by percent. Percentages are given as integers. 100 is the base and a larger number will brighten the image while a smaller number will darken the image.

-and andBits

Clear all colormap bits up to the given plane. This has the effect of darkening the image somewhat and shrinking the apparent depth of the image (and, consequently, the size of the color table). AndBits should be in the range [1-8] inclusive.

-or orBits

Set all colormap bits up to the given plane. This brightens the image somewhat and also shrinks the apparent depth of the image. When both -A and -O are specified, ANDing will occur before ORing.

-reverse

Reverse the colors in the image. The bits of each color used in the image are inverted.

-bw

Convert the source color image to a monochrome bitmap. All colors falling below the average color intensity are mapped to black. Others are mapped to white.

-halftone

Convert the source color image to a halftoned monchrome bitmap. Resolution is maintained by increasing the size of the image by a factor of four on both axes.

-mdither

Convert the source color image to a dithered monochrome bitmap. This is like halftoning, but resolution is sacrificed to keep the resulting image the same size as the original. The matrix dithering algorithm used with this option is most suitable for line-drawings and text. For more complex graphics the -dither option is recommended.

-dither

Convert the source color image to a dithered monochrome bitmap with the Floyd-Steinberg algorithm.

-nodither

Turns off any dithering. Use this if your XGRABSC environment variable specifies dithering and you want to override it to produce an undithered image.

OUTPUT FORMAT OPTIONS

-cps

Write output in Postscript format using the colorimage operator for color printers. Color to grayscale conversion is bundled into the output so you can actually use either color or cheaper grayscale printers. For monochrome displays, the -ps option will give more compact output.

-ps

Write output in Postscript format for greyscale printers. The number of bits per Postscript sample is determined by the depth of the image.

-xwd

Write output in xwd format. Use this if you want to convert to another output format with Pbm+.

Write output in FIxwd -xy format. This is like xwd, but allows black and

white images to be written with eight pixels per byte instead of the default one pixel per byte. While xwud and xpr will handle this format, some programs will not.

-bm

Write the output in X Bitmap format if the image is black and white, or X Pixmap format if the image is gray or color.

-bm2

Write the output in X Bitmap format if the image is black and white, or X Pixmap format 2 if the image is gray or color. -bm3 Write the output in X Bitmap format if the image is black and white, or X Pixmap format 3 if the image is gray or color.

-puzzle

Write output in a format suitable for loading into the puzzle program (see example below).

POSTSCRIPT OPTIONS

-compress

Enable or suppress Postscript image run-length encoding. Postscript output is normally compressed to minimize the size of output. If your printer can't handle compressed output, you should use -nocompress to turn off compression.

-eps

Create Encapsulated Postscript output, rather than normal stand-alone Postscript. This adds EPSF header comments and removes all scaling and translation of the image.

-l or -landscape

Use landscape layout (with page width and height exchanged) for Postscript output. This option is ignored if Encapsulated Postscript output is requested. Width and height may be specified with the -page option.

-bin

Write Postscript output in binary rather than using hexidecimal encoding. This causes the image portion of the output to use half as much space, decreasing transmission time to the printer. Note that not all print spoolers can handle 8 bit binary data, so this may not work on your system!

-limit

For Postscript output, check printer memory availability before attempting to print an image (the code to perform the checks is integrated into the output of xgrabsc). This is turned off if Encapsulated Postscript output is requested, and may be disabled completely when building the xgrabsc program. On the command line it may be turned off with -nolimit.

-preview or -prev

Selects Encapsulated Postscript output with an EPSI preview image in its header. The preview image, if necessary, is dithered to black and white either with a default dithering algorithm or one you specify on the command line (e.g., -mdither). Programs such as Frame use preview images to display the postscript image during editing sessions. If you don't have a preview image, Frame will display a blank rectangle. The image will print OK but you won't see it while editing.

-previewonly

Like -preview but writes only the preview portion, not the postscript image. This may be used to add the preview to an existing EPS file after having displayed it using a PostScript interpreter.

-page widthxheight-marginWidth-marginHeight

Sets the size of the paper and the borders you desire around the edge of the paper. Xgrabsc will reduce the image if necessary to keep it within the borders you specify. The default page size and margins are set when xgrabsc is built. Measurements are in inches (e.g., 8.5x11.0-0.5-0.5)

PROCESSING ORDER

Processing is done in five phases: 1) set up, 2) obtain image, 3) process colors, 4) poly->monochrome conversions, and 5) output conversion.

The set-up phase includes processing command-line options, sleeping, connecting to X-Windows, freezing the screen, and grabbing the mouse if necessary.

If the mouse is grabbed for rubber-banding, an upper-left-corner cursor is displayed until the left mouse button is pressed. A lower-left-corner cursor is then displayed while drawing rubber-rectangles until the mouse button is released.

If the mouse is grabbed for xwd-style window selection, an xwd-style cursor is displayed until the left mouse button is pressed.

The mouse is then released.

The bell is then run and the image is pulled from the screen.

Following the image-grab, the bell is run twice and the screen is released.

If the image is not monochrome, the color manipulation functions are then applied in this order: brighten, AND, and OR, reverse.

Only one polychrome to monochrome conversion is allowed. If none of these is chosen, the color table of a polychrome image is compressed in preparation for output conversion.

The output stream is then opened and the image is written in the selected output format.

ENVIRONMENT

DISPLAY - specifies the name of the display that xgrabsc should grab from.

EXAMPLES

      xgrabsc >outfile.ps

To write output in Postscript format and send to the printer, use

      xgrabsc | lpr

It is sometimes helpful to brighten an image somewhat before it is formatted for Postscript output. E.g., to brighten by 30%

      xgrabsc -b 130 | lpr

If your printer supports color, and your display is color, you can have xgrabsc generate color output instead of gray scale:

      xgrabsc -cps | lpr

The default Postscript output attempts to scale the image so that it will all fit on one page, and is centered on the page. If you are grabbing images to include in documents, such as with FrameMaker, you should ask for Encapsulated Postscript output with the -eps switch. For example:

     
  xgrabsc -eps -o image1.eps

To select an entire window, write output in puzzle format and read into the puzzle program, use the commands

      xgrabsc -click -puzzle >outfile.pzl

      puzzle -picture outfile.pzl

To have xgrabsc sleep for three seconds before rubber-banding, display processing information, and have the result displayed with xwud,

      xgrabsc -xwd -verbose -s 3 | xwud

To grab an image from another server and then reduce the colormap to three bits by ANDing, use

      xgrabsc -d other:0.0 -and 5 -bm >outfile.xpm

You will, of course, have to go to the other machine to select the image with that machine's mouse.

LIMITATIONS

The default screen visual is used as the visual for the image. Visuals are associated with particular windows, and xgrabsc pretends ignorance about any windows but the root.

This software has been tested with StaticGray and 8-plane PseudoColor on DECStations (using both UWS 2.2 and X11 Release 4). It has also been tested with 8-plane PseudoColor on Sun SparcStations and various other platforms using X11 Release 4 and Release 5.

X11 Pixmap format is rather verbose. You may want to run large images through the compress utility before storing them in a file. E.g.,

      xgrabsc -bm | compress >outfile.xpm.Z

AUTHOR

     Bruce Schuchardt
    Servio Corporation
      bruce@slc.com

ACKNOWLEGEMENTS

Some of the source code for xgrabsc came from the xloadimage project by Jim Frost (jimf@saber.com) and others. Jim's copyright has been included both here and in the source code.

The idea for using run-length encoding for Postscript output came from the xwd2ps project by Robert Tatar and Craig A. McGowan.

The ad2c.sed script that makes it possible to let you run xgrab without installing XGrab.ad everywhere is part of the ad2c package developed by George Ferguson.

CONTRIBUTORS

Yves Arrouye wrote the EPS Preview and page-configuration enhancements.

COPYRIGHT

Xgrabsc 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 cpyright.h 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.

THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.  

SEE ALSO

Index

NAME

SYNOPSIS

DESCRIPTION

GENERAL OPTIONS

SELECTION OPTIONS

IMAGE PROCESSING OPTIONS

OUTPUT FORMAT OPTIONS

POSTSCRIPT OPTIONS

PROCESSING ORDER

ENVIRONMENT

EXAMPLES

LIMITATIONS

AUTHOR

ACKNOWLEGEMENTS

CONTRIBUTORS

COPYRIGHT

SEE ALSO