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--Web-Prep Glossary and Index-- This Glossary is part of the WebPrep document about preparing text and graphics for the Web. Glossary terms below are linked (indexed) to the main text (if there is any relevant material in the main text). If the term itself is underlined, it links to WebPrep chapters; links within the explanation are to other Glossary terms or to other pages or email addresses. 0-9 1-bit, 3-bit, 8-bit, 24-bit, 36-bit One, 3, 8, 24, or 36 bits-per-pixel reserved to describe colors or sound. Use ipaste to display 24-bit color. See bit depth. 3D Three-dimensional. See also VRML. 44444 The extension to call for help at NAS. support@nas.nasa.gov Also known as "FourFours," an expression left over from when we only had to dial four digit extensions. A B Acrobat, Acrobat Distiller, Acrobat Exchange Programs from Adobe Systems for creating and reading PDF (Portable Document Format) documents. With an Acrobat viewer (on the NAS system, use the acroread command) PDF documents can be viewed on the Web in their original page layouts. The NAS Multimedia Lab has Acrobat Exchange and Distiller for creating PDF files. The next version will be named Amber. ActiveX A standard that allows software components embedded in Web pages to interact with each other and run in your browser, independently of the language (such as Java) that they were written in. Intended as a "glue" to tie together an assortment of technologies to enable "Active" Web sites. Created by Microsoft. Currently runs pretty much only on Internet Explorer. See http://www.microsoft.com/ie/ie3/activex.htm adaptive media Media on the Web that adapts itself to the person using it. Users state their preferences, and thereafter the website adapts to the individual user's preferences. See, for example, www.affinicast.com Amber New name for Acrobat. See entry above. Ames Technical Reports Server Online index of technical reports written at NASA Ames Research Center. Includes NAS Reports. And is part of the NASA Technical Reports Server. See http://jit.arc.nasa.gov/atrs animated GIF A gif file that includes more than one image. Appears in a browser as an animation. See http://www.adobe.com/studio/tipstechniques/GIFanimation/main.html or http://iawww.epfl.ch/Staff/Yves.Piguet/clip2gif-home/GifBuilder.htm apanel Audio control panel on SGI Indys and Indigo2s; used to select input device when recording audio .aiff files. Also sets input and output levels and rates. Dynamic, interactive program that can run inside a Web page; written in Java code. ARCGraph Device-independent, standard function libraries and utilities created by Eric Hibbard's group at Ames Research Center to provide cross-platform formats for storing moves and draws for 3D graphic objects. Used, for example, to store individual frames for time-varying CFD frames and other images created by PLOT3D or FAST. Aspect Ratio Relation of width to height. Scaling an image in a document program can cause aspect ratio problems; better to scale in your image application program, or use xv to scale or fix aspect ratio. audio Sound. Bad Magic Unix error message returned from some NAS file conversion utilities; usually means that the file is not of the expected type. bit depth The number of bits-per-pixel reserved to describe the colors in an image file. [Also used to describe sound files ]. In an image file, more bits means more possible colors. Different shades of the same tint count as different colors. For each bit available, the rbg values of one color can be listed. It does not matter how primary or unusual the color is: each color has rgb values that are listed in a color lookup table (this is for indirect color). The bit depth determines how long the LIST of colors can be. Each bit has 2 possible values (0 or 1). To find the number of possible colors, raise 2 to the power of the bit depth. A bit depth of 3 ("3 bits-per-pixel") yields 2 raised to the third power equals 8 colors. 1 bit = 2 colors 3 bits = 8 colors 4 bits = 16 colors 8 bits = 256 colors 16 bits = 65,536 colors 24 bits = 16,777,216 colors 36 bits = 68,719,476,736 colors Here is an example of a 3-bit color lookup table: 1 148 148 148 2 050 050 050 3 238 021 199 4 000 255 000 5 148 000 148 6 000 000 255 7 000 123 000 8 255 255 255 Bit depth is allocated for every pixel in the file. The greater the bit depth, the bigger the file; an 8-bit file is about 15% the size of a 24 bit file. Unless your image needs millions of colors, don't use more than 8 bits. For black and white (without shades of gray) use 1-bit!!! Use xv to change bit depth. Or Photoshop. See also: GIF and TIFF. Compare bit depth to resolution. Bit depth is similar to resolution in that greater bit depth shows more subtle variations in color. In a photograph, this allows the differentiation of areas that might appear all the same color with less bit depth. Bit depth also applies to the number of colors that a monitor is capable of displaying. bitmap image Image composed of pixels. "Bitmap" is used now as synonymous with raster to refer to color values at points, which together describe an image. The points are arranged on a grid. In an image file, each pixel has a designated color; the colors of the pixels can be changed, but there are no graphic objects as there are in vector graphics. Screen dumps are bitmaps. BoundingBox (BB) Coordinates of the lower-left and upper-right corners of the image in an EPS file. Takes the form: %%BoundingBox: llx lly urx ury where the coordinate llx is the lower left corner. In an EPS file, the BB statement MUST appear in the header. The PostScript coordinate system is based on points. One point = 1/72 in. Origin = lower left, and 612 792 = upper right (portrait orientation). browser Provides user interface to the Web. Allows user to access text, graphics, audio, 3-D data, and video. See Netscape and Mosaic. C D CAD Computer-Aided Design. Usually, vector-based drafting. The AutoCAD format, DXF, can be imported by FrameMaker 4. Capture (FrameMaker) A feature in the File Menu of the FrameMaker program; grabs a selected rectangle of whatever is on the screen. Xbm format. Variable quality. CGI, cgi-bin Common Gateway Inteface, a standard for interfacing external applications with information servers. Programs on a Web server, in the cgi-bin directory, used to provide special features such as forms processing, imagemap processing, text searching and URL redirection. A CGI program is executed in real-time, so that it can output dynamic information. Often written in Perl, Tcl, or as shell scripts. You can write your own CGI programs to perform special functions. AT NAS, contact web-team@nas.nasa.gov to install your cgi-bin scripts. See also: http://hoohoo.ncsa.uiuc.edu/cgi/primer.html or http://www.comvista.com/net/Web/cgi.html CGM Computer Graphics Metafile. Platform-independent interchange format for bitmap and vector data. Feature-rich, compact. At NAS, gplot can read and create CGM files, and FrameMaker can import CGM. compression Algorithms used to reencode data into a more compact representation conveying (approximately) the same info. Makes smaller files for roughly the same images. decimal tabs in FrameMaker tables Trick to use when you are trying to align numbers vertically on the decimal point: Create a new Paragraph tag = decimal.cell Apply decimal.cell to all columns containing decimals With cursor in a decimal cell, use Paragraph Designer, set decimal tab and apply to Paragraph Catalog Create an Autonumber (/t) in Paragraph Designer for decimal.cell To center the numbers in the column, use Resize from the Table menu; resize column to width of cells' contents. Doctor HTML A great site that checks your spelling and HTML. Documentation Center doc-center, in Building 258, upstairs; carries hard-copy documents relating to NAS, and PostScript files of many of the documents. Sometimes called "the library," not to be confused with the Ames Library, now called Research Information Resources, in Bldg. 202. Dump Screen (FAST) Means of creating .sgi files from images viewable in FAST. In FAST 1.1a, use VIEWER/Viewer/Save-Restore/Dump Screen. duplex double-sided printing (printing on both sides of the paper). At NAS, use lpr -Pqms2dup filename and look in rm 209 for the output. dvips Unix utility for converting TeX .dvi files to PostScript. DXF (CAD format) Date eXchange Format. Vector graphics file format used by AutoCAD. FrameMaker 4 can import DXF files. E F EPS or EPSF Encapsulated PostScript or Encapsulated PostScript Format. PostScript describing one page or less, with special header to make it easier to "swallow" by a text formatting program. The basic requirements for an EPS file are: The first line of the file must be: %!PS-Adobe-3.0 EPSF-3.0 (The version numbers can be different). Another line near the top must have the Bounding Box. The PostScript must be well-behaved (should not contain page size or fonts--except font names--should not call erasepage or quit). ALSO, to be displayed in most Web PostScript readers, the EPS file needs to have a screen preview image. To get a file into EPS, use tops or ps2epsi. EPSI EPS (see above) with a screen preview Image. Ez3d (previously called Movieola) from Radiance Software; commercially available software to create VRML models on SGI workstations. See http://www.webcom.com/~radiance/ FAST Flow Analysis Software Toolkit. A software environment created at NASA Ames Research Center. For visualizing data, particularly flow solutions. FAST Expeditions A type of "scientific expedition": a 3D, interactive exploration through scientific data with "what-if" capabilities. Instead of sending data as pixels to a movie player, data is sent in the form that can be analyzed by sophisticated analysis tools running on the recipient's computer. 3-D data interactive is a new medium for the Web. It allows much more information to be conveyed with much smaller files than movies. The users download scientific data files, then use a visualization program such as FAST to view the data. Pre-written scripts can be used for a guided tour of the data, or the users can explore the data on their own. FASTtreks short for FAST Expeditions. See entry above. Fetch telnet For the Macintosh, provides interactive access from the Mac to telnet hosts on the network (for example, workstations). Transfers files to and from the Mac. When putting or getting binary files, choose Raw Data, not MacBinary. fm2a Converts a FrameMaker file to formatted ASCII. fm2ahpp Semi-automatically converts a FrameMaker file to html. Works much better than fm2html. Contact CustCom for info. fm2html Old version of fm2ahpp. FrameMaker Document formatting program supported on the workstations at NAS. Gracefully imports many graphic file types, including: CCITT G4, CGM, EPS and EPSF (the graphic appears as a gray box on the screen in FrameMaker, but prints correctly and displays in PostScript viewers), EPSI (this is EPS with a screen preview image), PICT, PCX, Sun rasterfile (rf), TIFF, and xwd. Use the File/Print menu to dump a PostScript file of the document. To start FrameMaker from system prompt, type maker. See also fm2ahpp, our section on FrameMaker. and NAS FrameMaker Users. Address FrameMaker questions to framers@nas.nasa.gov To join the framers list, send email to nasinfo@nas.nasa.gov ftp File Transfer Protocol, used to move files from one machine to another. Fetch for the Macintosh has a good ftp utility. G H ghostscript PostScript-style freeware on the NAS system; also available from GNU Software, tim@cs.wisc.edu ghostview PostScript viewer, part of "ghostscript" (See above). GIF Graphic Interchange Format. (Pronounced "JIFF" like the peanut butter). A graphic file format created by CompuServe Inc., used to store bitmap images and exchange them between platforms. Can store multiple images in one file. 1 to 8 bits-per-pixel. LZW compression. The most widely used graphics format on the Web; all graphical browsers read GIF. See also http://www.put.poznan.pl/hypertext/Internet/faq/t-gif/transparent.html GNUPLOT Command-driven interactive function plotting program. gplot Post processing utility for CGM metafiles. On IRIX 5.2, gplot is in /usr/new/bin. On vn, it is in /usr/unsupported/bin. gra An ARCGraph file extension, for a mixture of graphic types. graphical information map See Imagemap. graphic A drawing made in accordance to the rules of mathematics. Strictly, a computer graphic file contains vector art, as opposed to bitmap art. Graphic is used loosely to mean any art. Graphics Lab See Visualization Lab gs GhostScript. help at NAS Nas User Services. Extension 44444, or 415-604-4444. support@nas.nasa.gov HEX Hexadecimal; a numerical system based on 16 digits. The lower digits are 0 through 9. The higher digits are A through F. On the Web, six-digit HEX numbers are used to specify (among other things) rgb color values. The first two places represent red, next 2 = green, last 2 = blue. For example, color="FF0000" would call for rgb 255,0,0 which is pure red. For more info see http://www.davesite.com/webstation/html/hexchart.shtml or for an rgb to HEX converter, see http://www.public.iastate.edu/~cschan/rgb.html For a HEX color sampler see http://www.albany.net/~hfrankel/colorhex.htm HotJava Web browser built by Sun Microsystems to showcases the capabilities of the Java language. See JAVA. html HyperText Markup Language. The basic language of the Web. Used to create documents that are formatted by the Web browsers; that is, the formatting is not fixed by html; only styles--such as heading1--are assigned. See also the Web Weavers page for more info. I J IBM PC, getting files from See PC. image map A graphic (such as any of the alpha-pads in this file) that has been scripted with links. See also http://www.hway.net/ihip/ Import File menu/Import, in FrameMaker, used to bring graphic files into a document. Fairly robust and tolerant. IndyCam A digital camera that comes with some models of the SGI Indy.(IndyCam=trademark of SGI). Takes movies or stills, directly into digital files. Stays attached to the Indy. interlace Arrangement of data in a GIF file to allow the image to be viewed (on the Web) as it is being downloaded. An interlaced image displays starting with every eighth row, then every fourth, and so on, allowing more of the developing image to be "seen" than if displayed one line at a time from the top. There is service on the Web that will convert your .gif files to interlaced files. see: http://www.vrl.com/Imaging/interlace.html Or use ppmtogif. At NAS, use Photoshop to make interlaced GIFs. Or, on the NAS system, to interlace a GIF file, use: giftopnm image.gif | ppmtogif -interlaced > image-interlaced.gif To convert a TIFF file to an interlaced, transparent-background GIF, try this: tifftopnm filename.tiff | ppmquant -256 | ppmtogif -interlace -transparent rgbi:1/1/1 >out.gif intranet Web site for information within an organization, as opposed to a site that is open to the world-wide public. ipaste (for display) Utility for displaying image files on a SGI graphics workstation. Unlike xv, will display 24 bits. IRIX Unix operating system for SGI workstations. Java New object-oriented programming language developed at Sun Microsystems. Used on the Web to to run "applets" that allow sound and motion to be presented within Java-enabled browsers such as Netscape Navigator 2 or later. See http://java.sun.com/ See also HotJava. JavaScript A simple scripting language, almost totally unrelated to Java programming language. Runs on Navigator 2 later. See: http://www.netscape.com/comprod/products/navigator/version_2.0/script/ K L KQML Knowledge Query Markup Language landscape Orientation of a page with the long dimension horizontal, as a typical picture of a landscape. As opposed to portrait. LaTeX Preformatted version of TeX; command-based text formatter; author types directives into text file, then runs latex on the file, and gets a printable, formatted .dvi file. Easier to use than TeX, but still a pain if you aren't used to it. Not WYSIWYG. Good for formatting formulas. See latex2html. latex2html Converts LaTeX formatted files to html files. Calls many other programs and therefore is broken frequently. ledger Large size paper: 11"x17". At NAS, use lpr -Pqms2led filename and look in rm 209 for the output. link On the Web, a hyperlink to another place on the Web. For example, if you click here, your browser will open the titlepage of this document. The HTML coding for this page links the word here to the titlepage. It could have been linked to anywhere on the Web. Links are perhaps the most important feature of the Web. line art See vector. M N Macintosh, getting files from To get graphic files from a Mac to a workstation, save them in an interchange format such as GIF or TIFF or EPS or CGM. Use Fetch on the Mac to ftp the file to your workstation. FrameMaker MIF format can be saved on a Mac (or PC) and opened on a workstation. mailcap Configuration file that maps MIME types to external viewers. maker Command to evoke FrameMaker at NAS. Mathematica A math utility that allows users to apply mathematical transformations to symbolic inputs to derive symbolic results, numerical results, or Fortran programs. Use psfix to get Mathematica .eps files importable into FrameMaker. matlab Command to evoke MATLAB, matrix laboratory. Use psfix to get Mathematica .eps files importable into FrameMaker or xv meta data Data about data; keywords, etc. used to make the contents of a file more searchable. Using META tags in your HTML will help users find your page. See www.virtualpromote.com/metatag.html MIME type Multipurpose Internet Mail Extensions. Standard for indicating file type on the Internet. See list of extensions to MIME file types. Used with mailcap. Mosaic Mosaic, the first World Wide Web browser. Used to display text, graphics etc. from the Web. Movies Sequence of 2D images that alternate fast enough to simulate movement. Motion picture, animation. Multimedia Lab At NAS, a facility for helping NAS staff and NAS-system users create multimedia presentations, such as web pages, reports, summaries and professional papers. NAS The Numerical Aerospace Simulation facility, a supercomputing facility in building 258 at NASA Ames Research Center, Moffett Field CA. This glossary and the attached report are intended for NAS users. NAS Reports Papers written by NAS staff describing results of work. Our document, Web-Prep: How To Prepare Text and Media For the World Wide Web, is about preparing NAS Reports for the Web. All work-related documents by NAS staff --such as research results, professional papers, benchmark information, and user guides--are eligible to be NAS Reports. Making a paper a NAS Report is recommended because it gives the paper an identifying number and a place on the Web. See GUIDELINES for NAS Reports. For assistance, see NAS Reports Coordinator (entry below this) or CustCom. NAS Reports Coordinator Pam Walatka; person to contact for help with any stage of your potential NAS Report. Netpbm Newest version of pbm. Netscape Company that produces Navigator and the new Communicator browsers and servers for the World Wide Web. O P PageMaker Program on the Macintosh for formatting text and graphics. Can be saved in Adobe Acrobat PDF, viewable on the Web in original layout. paint programs Utilities to manipulate pixel images. At NAS, on the workstations, paint programs include pbmplus, pixedit. Adobe Photoshop 3.0 for the SGI is now available at NAS! Type photoshop on the command line. PC, transferring file from To get graphic files from a PC to a workstation, save them in an interchange format such as GIF or TIFF or EPS or CGM. For text files, FrameMaker MIF format can be saved on a PC (or Mac) and opened on a workstation. Use ftp on a NAS PC to transfer your files to a NAS workstation. PBM, pbm Portable Bitmap Utilities, pbmplus: freeware monochrome bitmap manipulation utilities. New version called netpbm. See also PBM Conversion Table. PCX PC Paintbrush File Format, also called DCX or PCC. Bitmapped. Mono, 4-bit, 8-bit or 24-bit. Widely used in PC land. PDF Portable Document Format, part of the Acrobat system from Adobe. Format allows any user with a PDF reader (free from Adobe or use acroread at NAS) to view documents in their original layout. Most browsers now open PDF automatically. To convert a PostScript file to PDF, use ghostscript or ps2pdf. Perl A language for processing text (derived from awk, C and sed). Compiled. Used extensively for writing CGI programs. May be eclipsed by JAVA? See: http://homepage.seas.upenn.edu/~mengwong/forms/ Photoshop A powerful utility for image creation and manipulation, available on the NAS workstations with the command photoshop. PICT Macintosh graphic file format, usually vector-based. Created, for example, by MacDraw. Easily placed in almost any Mac page layout program, but not usable in Unixland. pix, pixel The basic element of a bitmapped image. Picture element. The smallest unit on a display device, or the smallest unit in an image file. Often represented as a square, but actually is a sampling point. pixel editors Applications that allow manipulation of images (as opposed to vector graphics). At NAS, use pixtools (see below). Adobe Photoshop 3.0 for the SGI is available on NAS fileservers. pix2ps Converts an image file to a postscript image file. CAUTION: pix2ps does not create an Encapsulated PostScript (EPS) file; the .ps files are printable on PostScript printers, but cannot be imported into most documents. pixtools Suite of tools developed by Diana Choi and David Yip at NAS; includes pixedit, pix2ps, pixsave, pix2qms, pixconv. Available to the public from http://www.cosmic.uga.edu/. Specifically, see http://cognac.cosmic.uga.edu/abstracts/arc-12830.html. *pix* Use the man utilityname command to see more about these utilities: pixedit, pix2qms, pixsave, pixsize, pixtype, pixscan, gif2pix, gif2iris, pix2gif, pix2sun, pix2tiff, sgi2pix, pix2sgi, ras2pix, pix2ras, pixkodak. For the latest and longest list, use the man -k pix command. platform Hardware environment that supports the running of a computer system. A "cross-platform format" would work on many different types of computers. PLOT3D, PLOT3D format PLOT3D is a scientific visualization program developed by Pieter Buning at NASA Ames, and used throughout the world by thousands of CFD scientists. Keyboard-command driven. PLOT3D format is a standard for grid and solution files. portrait Vertical orientation for page setup, with the long edge (e.g., 11") vertical. For changing portrait files to landscape, see rotate. PostScript text and PostScript images Page description language created by Adobe Systems. Very widely-used, roughly device-independent. Can be either vector- or bitmap-based. High-level. Describes one page at a time. PostScript files can be viewed by some users on the Web with a PostScript display program such as GhostScript, but there is no good PostScript display program for the Macintosh. ppm A graphics format, subset of PBM. ppmtogif Converts a portable pixmap into a GIF file; use -interlace option for interlaced GIF and -transparent option for transparency. preview image See screen preview image. program, running program from browser Web browsers have the ability to launch programs. See our section on FAST Expeditions or our chapter on Java. ps Filename extension, or abbreviation, for PostScript files. ps2epsi. Converts a PostScript file to EPS with a screen preview image. ps2gif Converts PostScript to GIFF. PostScript filename must end in .ps. psfix Corrects the PostScript created by Matlab or Mathematica. Q R Quark Express On the Macintosh, a widely-used program for formatting text and graphics for printing. ras An extension for ARCGraph files; pixel file screen dump. raster Originally, a display device in which the screen is a matrix of pixels (the current normal graphics display). Now roughly synonymous with bitmap . To "rasterize" is to convert from graphic objects (vectors) to bitmaps; the process is also called RIP (Raster Image Processing). RealAudio Audio that plays in real time, without pre-downloading audio file. See: http://www.realaudio.com recordaiff Program on SGI Indys and Indigo2s that records audio .aiff files. relative path In Unix, the path to a file, relative to the location of a file that references the file. As opposed to an absolute path which by definition begins with a leading / character. Keep your graphic files in the same directory as your text file, or use caution with relative paths. remote collaboration Simultaneous viewing (of scientific data) at multiple sites, with swapping of control. See also, www.ncsa.uiuc.edu/SDG/IT94/Proceedings/DDay/clucas/clucas.html or www.nas.nasa.gov/Software/FAST/FASTexpeditions/paper/paper.html for a paper by Jean Clucas and Val Watson. Report See NAS Report. resolution The measure of detail in an image. The physical size of an image in number of pixels wide by scan lines long. Also expressed as per-inch, as in 72 dpi (dots per inch). 72 dpi is the resolution for images to be displayed on the Web. Whereas bit depth refers to the number of colors available per pixel, resolution refers to the number of pixels. rgb Red, Green and Blue, the three primary colors of light. At NAS, used to denote an image file type; same thing as .sgi, almost the same thing as .pix. Use pixtools to convert back and forth from .pix to .sgi files. The continuous-tone Kodak printers at NAS print rgb files (and PostScript). Use xv to convert other graphic file types to rgb. For the Web, use xv to convert .rgb files to .gif files. rotate Change portrait orientation to landscape. The easiest way to rotate a graphic for the Web is in xv. Click one of the little curved arrows in the lower right corner or the xv control panel. A PostScript file can be rotated in ghostview. Or, if possible, take care of page orientation problem within your graphics application. See also: ourPostScript section. S T sampling rate Samples per second in audio file. sampling format Bits per sample in an audio file, for example 8 bit or 16 bit. scanners Devices for converting hard copy images or text to digital files. screen preview image Part of an EPS file header that allows the graphic to be displayed on the screen (as opposed to printed on hard copy). If you get a gray box where your graphic should be, you need a screen preview image. Use ps2epsi. sgi format Native image file format for Silicon Graphics workstations. Bitmapped. See our section on file conversion utilities. Shockwave Macromedia's format for delivering multimedia on the Web. Runs on Macs and PCs. See http://www.macromedia.com Showcase Program that comes with SGI graphic workstations; uses vector graphics. Can "place" bitmap images. Fairly good for adding text or arrows to images. Has hyperlink capability. snapshot Utility for capturing images on the display screen. streaming Presenting multimedia data in a real time stream from server to browser, eliminating the need to download big data files. Feature of new generation of browsers. Available on old browsers in special-case audio. Sun rasterfile (rf) Sun Raster, native bitmapped format for Sun Microsystems UNIX platforms. tables Are supported by HTML3.2 Tech-Pubs See CustCom. TeX Pronounced "tech." Text formatting and typesetting program that uses commands interspersed in text. Not WYSIWYG. TeX outputs a typesetter independent file (called DVI which is short for DeVice Independent). Use latex2html to create an HTML file for the Web. Good for formatting formulas. An easier-to-use version of TeX is LaTeX. TIFF Tag Image File Format. 1 to 24-bit, compressible, very popular bitmap file format. Can be used on almost any platform. Excellent quality. Produces large files. tops Utility available at NAS for converting an sgi or rgb image file to bitmap PostScript, with the option of encapsulating it. for b+w: tops filename.sgi -eps > filename.eps for color: tops filename.sgi -eps -rgb > filename.eps The odd thing is that the option (-eps) follows the filename. Don't forget the " > ". To check the eps file use: gs filename.eps If you get a grey box when you import the EPS into a document program, use ps2epsi. transparent GIF An image file with a transparent background, allowing the color of the browser background to show through. Gives the appearance that an object is floating on the browser, rather than enclosed in a rectangle. You can do gif transparency by using ppmhist or xv to find the color index for the background, then giving that color as a -transparent color to the final ppmtogif. NAS also has the giftrans program online. see also: http://www.put.poznan.pl/hypertext/Internet/faq/t-gif/transparent.html Also, Photoshop has a File/Export/GIF89a utility for saving files as transparent GIFs. troff Text formatting and typesetting language that was popular before WYSIWYG editors became available. U V Unix Operating system used at NAS. vector graphics Computer graphic files based on graphic objects. Vectors are quantities specified by magnitude and direction; vector graphics are specified by specific points and qualities. For example, a line is specified as being drawn from point x1, y1 to point x2,y2 with a specified line width and perhaps a specified arc. Within a vector drawing program such as Adobe Illustrator, the line can be selected, moved and changed. Vector graphics are the opposite of bitmap graphics. Viewgraphs, Web use of Most viewgraph file formats are unacceptable for the Web but the contents of viewgraphs are often desirable. Save the files as plain text and then reformat them in HTML, or ask for help from the Multimedia Lab. You could use Web Presenter to make the viewgraphs (again, ask the Multimedia Lab). Visualization Lab VisLab. NAS facility near the lobby in Bldg. 258, where visualization experts help NAS people create images, video, audio, etc. VRML Virtual Reality Markup Language; protocol and file format standard for 3D graphic object language, analogous to HTML. Online standard developed and released as freeware by Mark Peche and Anthony Parisi's InterVista Software. VRML was adapted from Open Inventor from Silicon Graphics, with help from Gavin Bell. Displays a 3D model which the user can navigate through. Includes links. See http://vrml.wired.com/ or http://www.vrml.org The Multimedia Lab has staff to help NAS staff with VRML. W X wwwmaster@nas.nasa.gov email address for the NAS Web administrator: Andrew Hoag. For a complete listing of the NAS Web team, click on the big image on the NAS home page, or see http://www.nas.nasa.gov/ WebToon World Wide Web Cartoon. WebToons use images of humans with word balloons that are links to information within the document. Web Weavers People who create documents for the Web. See Chris Beaumont's Web Weavers Page. Word Microsoft Word. WorldView WorldView viewer for VRML. World Wide Web (Web) The part of the Internet that offers information in multimedia format-- text, graphics, audio, video, and 3D data interactive-- to anyone with a Web browser and a computer connected to the Internet. xbm Bitmap graphic file format, acceptable for images on the Web. See PBM graphic file conversion table. xpm X PixMap. Bitmap graphic file format. Standard format supported by many image editors and file converters. xv Interactive image display and manipulation program for the X Window System. Displays images in the GIF, JPEG, TIFF, PBM, PGM, PPM, X11 bitmap, Utah Raster Toolkit RLE, PDS/VICAR, Sun Rasterfile, BMP, PCX, IRIS RGB, possibly PostScript, and PM formats on workstations and terminals running the X Window System, Version 11. Allows changing file format, resizing, cropping, etc. Documentation is available on the NAS SPS machines; use man xv on sally. xwd X Window Dump. Bitmap graphic file. Created (for example) by FrameMaker's File/Capture feature, and importable by FrameMaker. Variable quality.

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Curator: Mark Wallace	Last Update: September 29, 2003
NASA Official: Walt Brooks	NAS-96-002