Note: the formatting of this document is somewhat messy due to the process by which it was created from the original HTML page, but all of the information is present in the form of "link to:" messages following each item that was a hypertext link in the original page. Transparent/Interlaced GIF Resources (link to: "http://www.pointcom.com/") (link to: "http://home.netscape.com/") The Transparent/Interlaced GIF Resource Page *** Version 2.51 (2/12/96) *** This document resides at http://dragon.jpl.nasa.gov/~adam/transparent.html (link to: "http://dragon.jpl.nasa.gov/~adam/transparent.html") The Highlight If you're doing everything right but your GIFs are coming out wrong, check the list of known bugs (link to: "bugs.html") involving transparency and interlacing. Contents Disavowal of Originality (aka: Standing On the Shoulders of Giants) (link to: s of Giants)) Introduction (link to: "#Introduction") Tools by Platform: (link to: "#Tools") (link to: "#DOS/Windows")DOS/Windows ( link to: "#Mac")Mac (link to: "#Unix")Unix (link to: "#Online")Online Programming (C) (link to: "#Programming") Further References (link to: "#References") Disavowal of Originality Actually this document is not the first of its kind. Check out some of the other pages that have already been devoted to the subject: Creative Internet's Transparent GIF info page (link to: "http://www.galcit.caltech.edu/~ta/tgif/transgifnotes.html") Yahoo's resource list (link to: "http://www.yahoo.com/Computers/World_Wide_Web/Programming/Transparent_Images/") Transparent Images page (link to: "http://melmac.corp.harris.com/transparent_images.html") by Chuck Musciano (Nice tutorial, for dumb folks like me.) And other Web pages that include related information: SIGWEB's mac-comms-utils page (in the UK) (link to: "http://www.qub.ac.uk/sigweb/mac-comms-utils.html#stillc") (Mac Utilities) Aaron Giles' project pages (link to: "http://guru.med.cornell.edu/~giles/projects.html") (Transparency for the Mac) They don't seem to mention interlacing, though, so perhaps there's a raison d'etre ("raisin of being") for this page after all. Introduction Wondering what transparent or interlaced GIFs are? A transparent GIF is an image that has a certain bit set on one of its colormap entries, so that a Web browser's background will show through wherever that color appears in the image. The GIF image at the top of this page is really rectangular, but the image background around the blob is set to be transparent, so that the page background shows through. (If you don't see this, you are experiencing Netscape bug #3 in my unofficial bug list. (link to: "bugs.html") Try reloading the page.) An interlaced GIF, instead of being transmitted and displayed top-to-bottom like a normal image, is first displayed at its full size with a very low resolution, then at a higher resolution, until it finally attains a normal appearance. After initially being enchanted by interlacing, I have come to regard it as a useless and annoying tric k in most cases (interlaced images take longer to redisplay, and interlacing combined with transparency tends to bring out bugs in Netscape), but it may still have its uses. See also Thomas Boutell's WWW FAQ. (link to: "http://www.boutell.com/faq") Transparency is supported on almost all graphical browsers, while interlacing may not be on some; however, it has no ill effects (or any effects whatsoever) on those that do not support it. (link to: "#Contents")Return to table of contents Tools by Platform DOS / Windows General: These utilities, as well as nearly any other free/shareware programs for PCs, are archived at the SimTel mirror sites. If you have trouble with any of these links, try one of the other SimTel mirrors, (link to: "pcmirror.html") in a directory something like "win3/graphics". There is a beautifully done page on working with GIFs at the Guide to Digital Pictures & More. (link to: "http://www.algonet.se/~dip/") It will be slow loading for US users, but you may find it worth it. Transparent Images: For DOS, I refer you to The Transparent Images page, (link to: "http://melmac.corp.harris.com/transparent_images.html") which gives a cookbook method for using the "giftrans" utility listed below. Adobe's GIF89a Export (link to: "http://www.adobe.com/Software.html#gif89win") [341 Kb], a PhotoShop plug-in for producing transparent GIFs (Windows) giftrans.exe (link to: "http://melmac.corp.harris.com/files/giftrans.exe") (DOS) Interlaced Images: Graphics Workshop for Windows (link to: "http://www.north.net/alchemy/gww.html") (Windows) WinGIF (link to: "ftp://ftp.best.com/pub/craig/windows_apps/wingif14.zip") (Windows) Both Transparent and Interlaced Images: Paint Shop Pro 3.11 (link to: "ftp://ftp.winternet.com/users/jasc/psp311.zip") [1880 Kb], a full-featured graphics manipulation package (Windows) [Instructions here] (link to: "psp311-info.html") LView Pro 1B (link to: "ftp://ftp.uoknor.edu/mirrors/SimTel/win3/graphics/lviewp1b.zip") [305 Kb], anothe r full-featured graphics manipulation package (Windows) [Instructions here] (link to: "http://www.magi.com/~kk/transg.html") [Or here] (link to: "http://www.infi.net/~rdralph/icons/tutorial/") GIF Construction Set for Windows (link to: "http://www.north.net/alchemy/gifcon.html") (Windows) VuePrint (link to: "http://www.primenet.com/~hamrick") (Windows) GDIT (link to: "ftp://ftp.demon.co.uk/pub/winnt/gdit.zip") (GD InTerpreter) is a new program that not only produces T/I GIFs but also edits or creates new GIFs on the fly, for use in CGI scripts in which, for example, there is dynamic data to be plotted. (Windows 32) SnapShot/32, (link to: "http://198.207.242.3/authors/gregko/snap32.htm") a screen capture utility that offers T/I GIF output (Windows-95 and NT) GIFTOOL, (link to: "http://www.homepages.com/tools/") a command line tool with batch conversions, comment adding, etc. (DOS) GDS, (link to: "ftp://ftp.netcom.com/pub/ph/photodex") a graphical utility for cataloging, viewing, and converting graphics files (also available at SimTel mirrors, (link to: "pcmirror.html") under "msdos/graphics") (DOS) (link to: "#Contents")Return to table of contents Macintosh General: Virtually all Mac free/shareware is distributed from the Info-Mac FTP site, (link to: "ftp://sumex-aim.stanford.edu/info-mac") including most of the programs listed below. Since this site is overloaded, some of the links below point instead to one of its mirror sites, uiarchive.cso.uiuc.edu. (link to: "ftp://uiarchive.cso.uiuc.edu/pub/systems/mac/info-mac") If you still have trouble with any of the following links, or if you are not located in the US, try another Info-Mac mirror (link to: "macmirror.html") site, in a directory something like "/pub/info-mac/_Graphic_&_Sound_Tool/_Graphic". There is also a concentration of graphics utilities and file specs for the two GIF formats (for programmers) at U. Texas, (link to: "ftp://ftp.utexas.edu/pub/mac/graphics") which seems to have a partial mirror of the Info-Mac archives. You will find a very attractive and complete cookbook on creating T/I GIFs at Stephen Collins' Web66 Cookbook page (link to: "http://web66.coled.umn.edu/Cookbook/contents.html") (under "A More Appetizing Presentation"), which also includes recipes for all other aspects of Web server administration. This site maintains local copies of the binaries for all of the required software (listed below), which saves you the hassle of trying to get them from the usual overcrowded FTP sites. Transparent images: Transparency (link to: "ftp://uiarchive.cso.uiuc.edu/pub/systems/mac/info-mac/_Graphic_and_Sound_Tool/_Graphic/transparency-10.hqx") [35 Kb] IconToGIF, (link to: "http://rhino.harvard.edu/dan/IconToGIF.html") a program to create transparent GIFs from desktop icons Interlaced Images: GIFConverter (link to: "http://www.kamit.com/gifconverter.html") Both Transparent and Interlaced Images: Adobe's v3.0.5 Update (link to: "http://www.adobe.com/Software.html#ps305mac") (for Photoshop v3.0.4) includes a GIF89a Export plug-in that provides transparency and interlacing PhotoGIF, (link to: "http://www.aris.com/boxtop/PhotoGIF") a PhotoShop plug-in that provides interlacing and transparency Graphic Converter (link to: "ftp://uiarchive.cso.uiuc.edu/pub/systems/mac/info-mac/_Graphic_and_Sound_Tool/_Graphic/graphic-converter-23.hqx") [1143 Kb], a fairly polished and versatile program Clip2GIF (link to: "ftp://uiarchive.cso.uiuc.edu/pub/systems/mac/info-mac/_Graphic_and_Sound_Tool/_Graphic/clip-to-gif-07.hqx") [118 Kb], a freeware scriptable program for converting PICT to GIF and JPEG (link to: "#Contents")Return to table of contents Unix General: All of the more common X11 applications are archived at the central FTP distribution site, (link to: "ftp://ftp.x.org") under the "contrib" or "R5contrib" directories. Several of the programs listed below are referenced to this site, but if you have trouble with the links, try the mirror at Sunsite (link to: "ftp://sunsite.unc.edu/pub/X11/contrib") o r one of the other mirrors. (link to: "xmirror.html") NOTE TO SILICON GRAPHICS USERS: SGI machines come standard with a graphic utility called "imgworks" that handles both transparency and interlacing, so you need not bother with any of this software. Transparent images: The Transparent Images page (link to: "http://melmac.corp.harris.com/transparent_images.html") is (once again) the place to look, with a nice tutorial to walk you through the process (this is Unix, after all, so instead of menus and buttons it is a process). But if you just want links to the tools themselves: giftrans.c, (link to: "http://melmac.corp.harris.com/files/giftrans.c") a command-line C program XV 3.10 (link to: "ftp://ftp.cis.upenn.edu/pub/xv/xv-3.10a.tar.gz") [3315 Kb], which does NOT support transparency, but which you will want to use in conjunction with "giftrans" (to get color indices), and which you should have anyway, just on general principles ImageMagick, (link to: "ftp://ftp.x.org/contrib/applications/I mageMagick/") which provides command-line conversion between many popular image formats (Use "convert"), as well as a point-and-click interface for image manipulation (Use "display"), including transparency Interlaced Images: The PBMPLUS graphics conversion package (link to: "ftp://ftp.x.org/R5contrib/pbmplus10dec91.tar.Z") [678 Kb] (Use "ppmtogif -interlace") Both Transparent and Interlaced Images: GIFTOOL, (link to: "http://www.homepages.com/tools/") a command line tool with batch conversions, comment adding, etc. The NETPBM graphics conversion package (link to: "ftp://ftp.x.org/R5contrib/netpbm-1mar1994.tar.gz") [825 Kb] (Use "pnmtogif -trans -interlace") WebGIF (link to: "http://www.boutell.com/gd/#webgif") is a utility built on the GD libraries (see Programming (link to: "#Programming")). GIFMOM, (link to: "http://www.louisville.edu/public/jadour01/mothersoft/gifmom/") also built on the GD libraries, operates on piped image data as well as on image files. GDIT (link to: "ftp://ftp.de mon.co.uk/pub/unix/unix/gdit/gdit.tar.gz") (GD InTerpreter) is a new program that not only produces T/I GIFs but also edits or creates new GIFs on the fly, for use in CGI scripts in which, for example, there is dynamic data to be plotted. You will need the GD library (see Programming (link to: "#Programming")). (link to: "#Contents")Return to table of contents Online (Platform-Independent) If you really groove on doing things across the net, you can actually exchange your old worn-out GIFs for shiny new T/I GIFs online, using some smart Web pages. However, note that you probably need to be running an HTTPD server on your computer in order to use these services; they generally ask you for the URL of an image, and then open their own connection as a client to your server, fetch the image by HTTP, and manipulate it. Transparent Images: Fefe's Transparency Apparatus, (link to: "http://www.inf.fu-berlin.de/~leitner/trans/") point-and-click, very easy. Located in Germany, so probably the most conveni ent for European users. Creative Internet site (link to: "http://www.galcit.caltech.edu/~ta/tgif/tgif.html") MIT Transweb page (link to: "http://www.mit.edu:8001/transweb.html") Both Transparent and Interlaced Images: VRL Image Machine (link to: "http://www.vrl.com/Imaging/") (also various other services) (link to: "#Contents")Return to table of contents Programming (C) Programmers, take heart! Thomas Boutell's GD (link to: "http://www.boutell.com/gd/") is a C graphics manipulation library that provides calls for performing all sorts of operations on GIF images, including transparency and interlacing. You might also be interested in the GD InTerpreter, GDIT (for Unix (link to: "ftp://ftp.demon.co.uk/pub/unix/gdit/gdit.tar.gz") or 32-bit Windows) (link to: "ftp://ftp.demon.co.uk/pub/winnt/gdit.zip"). File specs for GIF87a and GIF89a can be had at U. Texas archives. (link to: "ftp://ftp.utexas.edu/pub/mac/graphics") (link to: "#Contents")Return to table of contents Further Referenc es I have compiled a brief list of commonly observed bugs (link to: "bugs.html") involving transparency and interlacing, which may save you from knocking yourself out trying to fix a problem that is inherent to your browser. The best resource in the universe for tricky problems with Web graphics is the Usenet newsgroup comp.infosystems.www.authoring.images. (link to: "news:comp.infosystems.www.authoring.images") Make sure your news host is defined in your browser's preferences in order to access any newsgroup. You all might want to check out Bryan Woodworth's WWW Graphics Page, (link to: "http://www.best.com/~bryanw") (shut down "until further notice" as of Feb. 10, 1996) which is muy bueno for all kinds of graphics stuff (it has links to a lot of the sites I've mentioned, and much, much more). For pointers to archives of downloadable GIFs, try Yahoo, (link to: "http://www.yahoo.com/Computers/World_Wide_Web/Programming/Icons/") or get the compressed tar file of graphics (~375 GIFs) from Stanford's ar chives. (link to: "http://www-pcd.stanford.edu/gifs/") For imagemap info, NCSA has a general tutorial (link to: "http://wintermute.ncsa.uiuc.edu:8080/map-tutorial/image-maps.html") aimed primarily at Unix users, Joseph Walker has a more complete introduction (link to: "http://www2.ncsu.edu/bae/people/faculty/walker/hotlist/imagemap.html") to the topic and list of resources, and the WWW FAQ has a list of imagemap-making programs (link to: "http://sunsite.unc.edu/boutell/faq/imagemap.htm") for various platforms. There's also a very friendly Imagemap Help Page (link to: "http://www.hway.net/ihip/") from the folks at Hiway Technologies. NOTE: You may rest assured that I am happy -- no, more than that, ecstatic -- to help you with any remaining questions or related issues, but before you send me email, PLEASE do me (and yourself) a favor and look first at the WWW FAQ (link to: "http://www.boutell.com/faq/"), which in all likelyhood has the answer to your question. It'll be faster for you, and easier for me. Thank you too much. Speaking of FAQ's: Where, you may ask, could you get any other FAQs, if you so desired? You could FTP to MIT archives (link to: "ftp://rtfm.mit.edu/pub/usenet-by-hierarchy") or University of Lyon (link to: "ftp://grasp.insa-lyon.fr/pub/faq-by-newsgroup") archives which contain archives by newsgroup of every FAQ there is, or you could use the Usenet FAQ (link to: "http://www.cis.ohio-state.edu/hypertext/faq/usenet/top.html") Web page at Ohio State, which includes all FAQs posted in the news.answers group. For a complete FAQ reference (finding them, writing them, falling in love all over again with them), see Infinite Ink's (link to: "http://www.jazzie.com/ii/internet/faqs.html") comprehensive page on the subject. (link to: "#Contents")Return to table of contents Additions and corrections to this document are welcome. Adam Bernstein / adam@dragon.jpl.nasa.gov (link to: "/~adam/homepage.html") You can send me Email. (link to: "mailto:adam@dragon.jpl.nasa.gov")