 xref comp graphic 39078 alt graphic pixutil 5408 alt binari pictur util 4362 alt binari pictur 8964 alt binari pictur erotica 15266 comp answer 613 alt answer 249 new answer 8117 newsgroup comp graphic alt graphic pixutil alt binari pictur util alt binari pictur alt binari pictur erotica comp answer alt answer new answer path edu!tgl from tgl+ tom lane subject jpeg imag compress frequent ask question messag-id followup-to alt binari pictur summari us info jpeg jpg imag file program keyword jpeg imag compress faq sender new usenet new system supersed nntp-post-host gp repli-to jpeg-info uunet uu net organ school comput scienc carnegi mellon date mon 3 mai 1993 03 15 23 gmt approv new-answer-request mit edu expir mon 31 mai 1993 03 14 50 gmt line 1034 archiv-name jpeg-faq last-modifi 2 mai 1993 thi faq articl discuss jpeg imag compress suggest addit clarif new version 18 april 1993 new version xv support 24-bit view x window new version dvpeg imag alchemi do new version imag archiv pmview os 2 new list mgif monochrom-displai atari thi articl includ section 1 what jpeg? 2 why jpeg? 3 when jpeg stick gif? 4 how well jpeg compress imag? 5 what good qualiti set jpeg? 6 where jpeg softwar? 6a can softwar viewer 6b sourc code 7 what's hoopla color quantiz? 8 how jpeg work? 9 what lossless jpeg? 10 why argument file format? 11 how recogn file format it? 12 what arithmet code? 13 doe loss accumul repeat compress decompress? 14 what rule thumb convert gif imag jpeg? section 1-6 basic info jpeg user section 7-14 advanc info curiou thi articl post 2 week you find latest version new answer archiv rtfm mit 18 70 0 226 by ftp fetch pub usenet new answer jpeg-faq ftp send e-mail mail-server rtfm mit bodi send usenet new answer jpeg-faq mani faq articl store archiv for instruct archiv send e-mail address help quot separ line if repli server misread return address add path mynam mysit correct e-mail address repli ---------- 1 what jpeg? jpeg pronounc jai-peg standard imag compress mechan jpeg stand joint photograph expert group origin committe wrote standard jpeg design compress full-color grai-scale digit imag natur real-world scene it work well non-realist imag cartoon draw jpeg handl black-and-white 1-bit-per-pixel imag handl motion pictur compress standard compress type imag work committe name jbig mpeg jpeg lossi mean imag decompress ident origin the algorithm achiev compress exploit limit human ey notabl fact small color detail perceiv well small detail light-and-dark thu jpeg intend compress imag look human if plan machin-analyz imag small error introduc jpeg problem invis ey a properti jpeg degre lossi vari adjust compress paramet thi imag maker trade file size output imag qualiti you extrem small file mind poor qualiti index imag archiv make thumbnail view icon convers happi output qualiti default compress set jack qualiti satisfi accept lesser compress 2 why jpeg? there good reason imag file smaller store 24-bit-per-pixel color data 8-bit-per-pixel data make imag file smaller big win transmit file network archiv librari imag be compress 2 mbyte full-color file 100 kbyte big differ disk space transmiss time! if compar gif jpeg size ratio more detail if view softwar support jpeg directli convert jpeg format view manipul imag even jpeg-capabl viewer take longer decod view jpeg imag view imag simpler format gif instanc thu jpeg essenti time space tradeoff time order store transmit imag cheapli it's worth note network phone transmiss involv time save transfer shorter file greater extra time decompress file i'll arithmet the reason jpeg gradual replac gif standard usenet post format jpeg store full color 24 bit pixel 16 color 8 256 fewer color if 8-bit displai hardwar advantag within coupl year 8-bit gif obsolet black-and-white macpaint format todai furthermor reason detail 7 jpeg gif exchang imag peopl vari color displai hardwar henc jpeg consider appropri gif usenet post standard 3 when jpeg stick gif? jpeg go displac gif entir type imag gif superior imag qualiti file size on thing learn jpeg kind imag appli as rule thumb jpeg superior gif store full-color grai-scale imag realist scene scan photograph materi jpeg superior 24-bit displai hardwar lot superior see 7 detail gif better imag distinct color cartoon draw in larg area pixel exactli color compress effici gif jpeg squeez file gif introduc visibl defect thi sort imag best gif form in singl-color border cheap gif file avoid jpeg file jpeg hard time sharp edg row pure-black pixel adjac row pure-white pixel exampl sharp edg tend blur high qualiti set again sort thing scan photograph fairli gif file border overlaid text the blurri objection text pixel high if gif lot small-size overlaid text jpeg comput-drawn imag rai-trace scene instanc fall scan imag cartoon term complex the complex subtli render imag jpeg well the semi-realist artwork fantasi draw plain black-and-white level imag convert jpeg you 16 grai level jpeg grai-scale imag it gif lossless grai-scale imag 256 level jpeg if exist librari gif imag wonder convert jpeg you lose imag qualiti section 7 argu jpeg imag qualiti superior gif appli format start full-color origin if start gif irretriev lost great deal jpeg thing wors howev disk space save justifi convert thi decis if convert gif librari jpeg 14 hint be prepar leav imag gif format gif convert well 4 how well jpeg compress imag? pretti darn well here sampl file size imag handi 727x525 full-color imag ship harbor the three file comparison purpos rest creat free jpeg softwar describ 6b file size byte comment ship ppm 1145040 origin file ppm format compress 24 bit 3 byte pixel byte overhead ship ppm z 963829 ppm file pass unix compress compress accomplish lot note other text-orient compressor ship gif 240438 convert gif ppmquant -fs 256 ppmtogif most save result lose color info gif save 8 bit pixel 24 see 7 ship jpg95 155622 cjpeg -q 95 highest qualiti set thi indistinguish 24-bit origin nonprofession eyebal ship jpg75 58009 cjpeg -q 75 default set you mighti darn close distinguish origin on-screen ship jpg50 38406 cjpeg -q 50 thi slight defect jpege origin still good imag qualiti post usenet pictur group ship jpg25 25192 cjpeg -q 25 jpeg's characterist blocki appar set djpeg -blocksmooth help still i've plenti usenet post poorer imag qualiti ship jpg5o 6587 cjpeg -q 5 -optim -optim cut tabl overhead blocki perfectli satisfactori preview index purpos note file tini compress ratio origin 173 1 ! in case jpeg file factor smaller gif compar qualiti -q 75 file bit good gif better full-color displai thi typic ratio real-world scene 5 what good qualiti set jpeg? most jpeg compressor pick file size imag qualiti tradeoff select qualiti set there widespread confus mean set qualiti 95 not 95 claim the qualiti scale pure arbitrari percentag the game jpeg pick lowest qualiti set smallest file size decompress imag indistinguish origin thi set vari imag observ rule thumb the default qualiti set -q 75 best choic thi set lowest expect defect typic imag try -q 75 defect except experiment purpos -q 95 -q 100 produc file three time larg -q 95 better qualiti if imag perfect qualiti -q 50 objection degrad on hand higher qualiti set avoid degrad the second case appli time convert gif jpeg the default -q 75 compress 24-bit imag -q 85 95 better convert gif 14 info if small file preview index purpos prepar toler larg defect -q set rang 5 10 -q 2 amus op art note qualiti set discuss articl appli free jpeg softwar describ 6b program base other jpeg implement imag alchemi complet qualiti scale some program provid numer scale high medium low -style choic 6 where jpeg softwar? most program describ ftp if ftp faq articl how find sourc if direct access ftp read ftpmail server articl that articl appear regularli new answer send e-mail mail-server rtfm mit send usenet new answer find-sourc bodi the anonym ftp list faq help --- usenet new answer ftp-list faq new answer archiv note list chang constantli if copi coupl month latest jpeg faq new answer archiv 6a if can softwar viewer the list system-specif program kind system if machin check portabl jpeg softwar describ list note list concentr free sharewar program internet commerci program list x window xv sharewar 25 excel viewer jpeg gif imag format it format convers simpl imag manipul it's ftp export lc mit 18 24 0 12 file contrib xv-3 00 tar z version 3 00 major upgrad support 24-bit displai improv brand bug lurk if prefer bleed edg stick version 2 21 export note version 2 21 good choic 24-bit displai 8-bit color convert 24-bit imag jpeg but 2 21 work fine convert gif 8-bit imag jpeg caution glitch version 2 21 check save normal size checkbox save jpeg file file blurri anoth good choic x window john cristi's free imagemagick packag export lc mit file contrib imagemagick tar z thi packag handl imag process convers task the imagemagick viewer handl 24-bit displai correctli colormap displai better slower color quantiz xv basic free jpeg softwar both larg complex packag if simpl imag viewer xloadimag xli xloadimag support jpeg latest releas 3 03 xloadimag free export lc mit file contrib xloadimag-3 03 tar z xli variant version xloadimag fan faster robust origin the current xli faster robust current xloadimag respect jpeg file ijg v4 decod xloadimag 3 03 hack-over v1 the xloadimag releas xli free export lc mit file contrib xli 1 14 tar z both program thing 24-bit displai ms-do thi cover plain do window os 2 program head on good choic eric praetzel's free dvpeg view jpeg gif file the current version 2 5 ftp sune uwaterloo 129 97 50 50 file pub jpeg viewer dvpeg25 zip thi good basic viewer work 286 386 486 machin the user interfac flashi function anoth freewar jpeg gif tga viewer mohammad rezaei's hiview the current version 1 2 simtel20 mirror site note file msdo graphic hv12 zip hiview requir 386 better cpu vcpi-compat memori manag qemm386 386max work window os 2 hiview current fastest viewer imag bigger screen for larger imag scale imag fit screen pan scroll viewer you prefer approach deni slow load larg imag consider note instal bit tricki read direct carefulli! a sharewar altern colorview do 30 thi easier instal freewar altern it user interfac spiffier-look person find harder --- keystrok inconsist behavior it faster dvpeg slower hiview hardwar for imag larger screen size dvpeg colorview speed faster hiview the current version 2 1 simtel20 mirror site note file msdo graphic dcview21 zip requir vesa graphic driver vesadrv2 zip vesa-tsr zip directori mani pc built-in vesa driver load vesa driver colorview complain driver miss a second sharewar altern fullview kick net stabl archiv locat the current version inferior viewer the author tell version fullview shortli submit simtel20 archiv time the well-known gif viewer compushow cshow support jpeg latest revis 8 60a howev cshow's jpeg implement good slow half speed viewer imag qualiti poor hi-color displai too bad it'd nice good jpeg capabl cshow sharewar 25 avail simtel20 mirror site note file msdo gif cshw860a zip due remark varieti pc graphic hardwar viewer work machin if work convers program convert jpeg gif view favorit gif viewer if hi-color hardwar gif intermedi format find targa-capabl viewer vpic5 0 reput thing hi-color displai the independ jpeg group's free jpeg convert ftpabl simtel20 mirror site note file msdo graphic jpeg4 zip jpeg4386 zip 386 extend memori these file do compil free sourc code describ 6b convert jpeg gif targa ppm format handmad softwar offer free jpeg gif convers tool gif2jpg jpg2gif these slow limit convers gif format 24-bit color output jpeg the major advantag tool read write hsi's proprietari jpeg format well usenet-standard jfif format sinc hsi-format file widespread bbse capabl version 2 0 tool free prior version sharewar get simtel20 mirror site note file msdo graphic gif2jpg2 zip note hsi format file post internet readabl non-pc platform handmad softwar sharewar imag convers manipul packag imag alchemi thi translat jpeg file jfif hsi format imag format it displai imag a demo version imag alchemi version 1 6 2 simtel20 mirror site note file msdo graphic alch162 zip note about simtel20 the internet's kei archiv site pc-relat program simtel20 full wsmr-simtel20 armi mil 192 88 110 20 simtel20 run non-unix system weird directori name document refer directori msdo graphic simtel20 pd1 if physic milnet expect slow ftp transfer rate simtel20 there internet site maintain copi mirror simtel20 archiv ftp user mirror site a popular usa mirror site oak oakland 141 210 10 117 keep simtel20 file pub msdo graphic if ftp capabl retriev file simtel20 e-mail inform post comp archiv msdo find if usa consult newsgroup learn nearest simtel20 mirror microsoft window there window program capabl displai jpeg imag window viewer gener slower do viewer hardwar window' system overhead note do convers program describ insid window do window the newest entri winecj free extrem fast version 1 0 ftp rahul net file pub bryanw pc jpeg wecj zip requir window 3 1 256-or-more-color mode thi no-frill viewer bad habit hog machin complet decod imag qualiti notic wors viewer but fast preview jview freewar fairli fast good on-line help write decompress imag window bmp format creat jpeg file view gif jview lack featur sharewar viewer bright adjust excel basic viewer the current version 0 9 ftp cica indiana 129 79 20 84 file pub pc win3 desktop jview090 zip mirror archiv internet site includ wuarchiv wustl winjpeg sharewar 20 displai jpeg gif targa tiff bmp imag file write format convert it nifti featur includ color-balanc adjust slideshow the current version 2 1 simtel20 mirror site note file msdo window3 winjp210 zip thi slow 286-compat version regist 386-onli version roughli 25 faster colorview sharewar entri 30 thi earli promis contend updat time point real advantag winjpeg if current version 0 97 ftp cica indiana file pub pc win3 desktop cview097 zip understand version appear author finish colorview do dvpeg do head work window full-screen mode window os 2 the file hobb nmsu 128 123 35 151 note check pub upload version --- hobb moder fast move upload perman directori pub os2 2 graphic jpegv4 zip 32-bit version free ijg convers program version 4 pub os2 graphic jpeg4-16 zip 16-bit version os 2 1 pub os2 2 graphic imgarc12 zip imag archiv 1 02 imag convers view pm graphic interfac strong convers function view bit weaker sharewar 15 pub os2 2 graphic pmjpeg11 zip pmjpeg 1 1 os 2 2 port winjpeg popular viewer window descript window sharewar 20 pub os2 2 graphic pmview85 zip pmview 0 85 jpeg gif bmp viewer gif view fast jpeg view fast huge amount ram speed program strong 24-bit displai support sharewar 20 macintosh most mac jpeg program reli appl's jpeg implement quicktim system extens quicktim instal to quicktim 68020 better cpu run system 6 0 7 if run system 6 instal 32-bit quickdraw extens built-in system 7 you quicktim ftp ftp appl file dt mac quicktim quicktim hqx as 11 92 file quicktim 1 5 better qt 1 0 wai with respect jpeg margin faster consider prone crash fed corrupt jpeg file howev applic compat problem qt 1 5 mac user mind quicktim's jpeg format pict jpeg usenet-standard jfif jpeg format see 10 detail if post imag usenet jfif format most program mention gener format the choic jpegview free program view imag jfif format pict jpeg format gif format it convert jpeg format the current version 2 0 big improv prior version get sumex-aim stanford 36 44 0 6 file info-mac app jpeg-view-20 hqx requir system 7 quicktim on 8-bit displai jpegview produc best color imag qualiti current mac jpeg viewer jpegview view larg imag memori mac viewer fact deal jpeg imag 640x480 pixel typic 4mb mac given larg imag jpegview automat scale fit screen present scroll bar viewer you zoom desir portion some peopl behavior overal jpegview's user interfac well thought gifconvert sharewar 40 imag viewer convert support jfif pict jpeg well gif imag format the latest version 2 3 2 get sumex-aim stanford file info-mac art gif gif-convert-232 hqx requir system 6 0 5 gifconvert better jpegview plain jpeg gif viewer extens imag manipul format convers capabl find worth sharewar fee lot plai imag also newest version gifconvert load save jfif imag quicktim best bet machin quicktim but faster quicktim note if gifconvert run memori load larg jpeg convert file gif jpeg convert view gif version jpeg convert mac version free ijg jpeg convers util sumex-aim stanford file info-mac app jpeg-convert-10 hqx thi mac file convers view you conjunct gif viewer previou version faq recommend imageri jpeg v0 6 jpeg gif convert base version ijg code if program definit replac jpeg convert appl's free program pictpixi view imag jfif quicktim jpeg gif format convert format you pictpixi ftp appl file dt mac quicktim qt 1 0 stuff pictpixi hqx requir quicktim pictpixi intend develop's tool best choic fool quicktim some drawback requir lot memori produc poor color imag qualiti 24-bit displai unfriendli user interfac wors pictpixi unsupport program mean minor bug appl intend there version pictpixi call pictcompressor float net if trash buggier also quicktim starter kit includ clean-up descend pictpixi call pictur compressor note pictur compressor not free distribut net storm technolog's pictur decompress free jpeg viewer convert thi program inferior program wai system 7 quicktim forc older system it 32-bit quickdraw machin you sumex-aim stanford file info-mac app pictur-decompress-201 hqx you set file type download imag file 'jpeg' allow pictur decompress open if machin 32-bit quickdraw mac plu instanc gifconvert choic singl-program jpeg view if pai gifconvert jpeg convert free gif viewer more commerci mac applic support jpeg deal usenet-standard jfif format adob photoshop version 2 0 1 read write jfif-format jpeg file jpeg plug-in acquir menu you set file type download jpeg file 'jpeg' allow photoshop recogn amiga most program list store aminet archiv amiga physik unizh ch 130 60 80 80 there mirror site archiv closest in usa good choic wuarchiv wustl mirror amiga physik unizh ch hamlab plu excel jpeg viewer convert well gener imag manipul tool it's cheap sharewar 20 read format jpeg the current version 2 0 8 a demo version amiga physik unizh ch mirror site file amiga gfx edit hamlab208d lha the demo version crop imag larger 512x512 fulli function rend24 sharewar 30 imag render displai jpeg ilbm gif imag the program creat anim captur frame on-the-fly render packag lightwav the current version 1 05 amiga physik unizh ch mirror site file amiga os30 gfx rend105 lha note directori supposedli amigado 3 0 program program amigado 1 3 2 04 2 1 viewtek free jpeg ilbm gif anim viewer the current version 1 04 amiga physik unizh ch mirror site file amiga gfx viewtek104 lha if spend real monei commerci packag support jpeg two written thoma krehbiel author rend24 viewtek these cinemorph standalon imag morph packag imagefx impress 24-bit imag captur convers edit paint effect prepress packag includ cinemorph both distribut great vallei product art depart profession adpro asdg inc commerci imag manipul softwar amiga imagemast black belt system well-regard commerci graphic packag jpeg support the free ijg jpeg softwar compil amiga amiga physik unizh ch mirror site directori amiga gfx conv file amigajpegv4 lha these program convert jpeg ppm gif targa format the amiga heavili infest quick-and-dirti jpeg program base ancient beta-test version free ijg jpeg softwar magazin publish disk-of-the-month notifi author among augjpeg newamyjpeg vjpeg heard in opinion older ijg version 3 march 1992 worth disk space store program trash newer atari st the free ijg jpeg softwar compil atari st tt atari archiv umich file atari graphic jpeg4bin zoo these program convert jpeg ppm gif targa format for monochrom st monitor mgif manag achiev four-level grayscal flicker version 4 1 read jpeg file avail atari archiv umich file atari graphic mgif41b zoo heard free sharewar jpeg-capabl viewer atari sure now? pointer appreci acorn archimed !changefsi suppli risc os 3 version 3 10 convert view jpeg jfif format provis convert imag jpeg cli doubl-click recent version 7 11 sharewar program translat handl jpeg 30 imag format while older version archimed bboard current version regist author john kortink nutterbrink 31 7544 wj ensched the netherland price 35 dutch guilder 22 10 pound there's commerci product call !jpeg jpeg read write function direct jpeg view well host imag format convers process option thi expens better program contact dt softwar freepost cambridg uk tel 0223 841099 portabl softwar system if fit situat compil free jpeg convers softwar describ 6b you'll viewer program if displai 8 bit gif viewer fine displai color capabl find viewer read targa ppm 24-bit imag file there numer commerci jpeg offer pop dai recommend spend monei find free sharewar softwar vastli slow in case purchas hardwar-assist product ask point question product compli final jpeg standard handl jfif file format earliest commerci releas compat els's file 6b if sourc code work free portabl c code jpeg compress independ jpeg group lead a packag sourc code document small test file place the offici archiv site sourc code ftp uu net 137 39 1 9 192 48 96 9 look directori graphic jpeg current releas jpegsrc v4 tar z thi compress tar file forget retriev binari mode you retriev file ftp uucp if pc cope tar z format prefer zip format find simtel20 mirror site note file msdo graphic jpegsrc4 zip thi file compuserv graphsupport forum go pic librari 15 jpsrc4 zip if ftp access retriev sourc nearest comp sourc misc archiv version 4 appear issu 55-72 volum 34 if retriev comp sourc misc post faq articl how find sourc refer top 6 the free jpeg code convers jpeg jfif format imag file gif pbmplu ppm pgm utah rle truevis targa file format the core compress decompress modul easili reus program imag viewer the packag highli portabl test machin rang pc crai we releas softwar noncommerci commerci compani basi jpeg-relat product we royalti acknowledg product literatur readm file distribut detail we hope softwar industri-qualiti --- free offer warranti accept liabil the independ jpeg group volunt organ contribut improv softwar join 7 what's hoopla color quantiz? most peopl full-color 24 bit pixel displai hardwar typic displai hardwar store 8 fewer bit pixel displai 256 fewer distinct color time to displai full-color imag comput map imag appropri set repres color thi process call color quantiz thi misnom color select better term we're stuck standard usag clearli color quantiz lossi process it turn imag detail color quantiz algorithm much impact final imag qualiti error introduc jpeg lowest jpeg qualiti set sinc jpeg full-color format convert color jpeg imag displai 8-bit-or-less hardwar requir color quantiz thi true color jpeg feed 256-or-less-color gif jpeg decompressor 256 color thousand color thi jpeg's lossi pixel differ pixel start ident color color each origin color smear group nearbi color therefor quantiz requir displai color jpeg colormap displai imag sourc the avoid quantiz grai-scale output incident meaningless talk number color jpeg imag even attempt count number distinct pixel valu jpeg decod roundoff error differ occasion post imag describ 256-color jpeg thi tell poster read faq convert jpeg gif jpeg classifi color grai-scale photograph number color concept jpeg on hand gif imag definit quantiz 256 fewer color a gif definit number color palett format allow 256 palett entri for purpos usenet pictur distribut gif advantag sender precomput color quantiz recipi thi disadvantag gif stuck sender's quantiz if sender quantiz number color displai re-quantiz poorer imag qualiti quantiz full-color imag furthermor sender high-qualiti color quantiz algorithm luck for reason jpeg offer promis better imag qualiti user machin match sender's displai hardwar jpeg's full color imag quantiz precis match user's displai hardwar furthermor advantag futur improv quantiz algorithm lot activ area purchas better displai hardwar better view jpeg imag with gif stuck forevermor it's worth mention gif-view program includ shoddi quantiz routin if view 256-color gif 16-color ega displai exampl wors imag thi partli inevit consequ color quantiz creat gif displai sloppi jpeg convers program forc high qualiti quantiz order accept normal quantiz directli number color displai thu jpeg provid better averag gif program low-color-resolut displai well high-resolut on! final ever-grow number peopl better-than-8-bit displai hardwar 15-bit hi-color pc displai true 24-bit displai workstat macintosh for peopl gif obsolet repres imag full capabl displai jpeg imag drive displai effect thu jpeg all-around better choic gif repres imag machin-independ fashion 8 how jpeg work? the buzz-word chromin subsampl discret cosin transform coeffici quantiz huffman arithmet entropi code thi articl's long i'm go for technic comp compress faq thi new answer archiv rtfm mit file pub usenet new answer compress-faq 1-3 if help new answer archiv top articl 9 what lossless jpeg? there's great deal confus subject the jpeg committe defin lossless compress algorithm guarante final output bit-for-bit ident origin input howev lossless mode common regular lossi jpeg algorithm offer compress at implement lossless jpeg exist commerci sai -q 100 free jpeg softwar doe not lossless imag what rid deliber loss coeffici quantiz step there good deal loss color subsampl step with v4 free jpeg code -sampl 1x1 turn subsampl keep mind commerci jpeg implement cope file even quantiz subsampl turn regular jpeg algorithm lossless subject roundoff error calcul the maximum error count pixel highli perceiv human ey concern machin process imag at minimum-loss set regular jpeg produc file half size uncompress 24-bit-per-pixel imag true lossless jpeg roughli amount compress guarante bit-for-bit accuraci if applic requir lossless storag imag 6 bit pixel color compon jbig bilevel imag compress standard thi perform better jpeg lossless imag jpeg lossless superior jbig imag 6 bit pixel jpeg public domain huffman jbig techniqu heavili cover patent 10 why argument file format? strictli speak jpeg refer famili compress algorithm refer specif imag file format the jpeg committe prevent defin file format turf war intern standard organ sinc exchang imag agre common file format leav problem in absenc offici standard number jpeg program writer thing result program compat els's the closest thing de-facto standard jpeg format work coordin peopl c-cube microsystem thei defin jpeg-base file format jfif jpeg file interchang format low-end format transport pixel tiff jpeg aka tiff 6 0 extens aldu tiff format tiff high-end format record want imag lot - tiff lot complex jfif well prove transport vendor histor implement incompat subset tiff it's ad jpeg mix improv situat both format develop input major vendor jpeg-relat product reason futur commerci product adher standard usenet adopt jfif replac gif pictur post jfif simpler tiff tiff 6 0 spec offici unus vagu crucial detail even tiff jpeg well defin jfif format support lowest common denomin tiff jpeg file transport a case peopl interest appl's quicktim softwar macintosh quicktim jfif-compat format wrap insid mac-specif pict structur convers jfif quicktim jpeg pretti straightforward mac program mac portion 6a if editor handl binari file strip quicktim jpeg pict jfif hand 11 detail anoth case handmad softwar's program gif2jpg jpg2gif imag alchemi these program capabl read write jfif format by default write proprietari format develop hsi thi format not readabl non-hsi program usenet post us -j switch jfif output thi appli version program current releas emit jfif format default you care post hsi-format file flame peopl non-pc platform 11 how recogn file format it? if alleg jpeg file softwar read hsi format proprietari jpeg-base format you inspect byte file 1 a jfif-standard file start charact hex ff d8 ff e0 variabl byte hex 00 10 'jfif' 2 if ff d8 start rest raw jpeg file thi decod as-is jfif softwar --- worth 3 hsi file start 'hsi1' you're luck hsi softwar portion file plain jpeg data decompress properli non-hsi program 4 a macintosh pict file jpeg-compress coupl byte header jfif header scan 'jfif' strip ff d8 read 5 anyth proprietari format jpeg if lucki file consist header raw jpeg data stream if identifi start jpeg data stream ff d8 strip in uuencod usenet post characterist jfif pattern m c x uuencod hsi file start m '-i if learn check save troubl download non-jfif file 12 what arithmet code? the jpeg spec defin modul final output compress data huffman code arithmet code allow the choic impact imag qualiti arithmet code produc smaller compress file on typic imag arithmet code produc file 5 10 percent smaller huffman code all file-size number cite huffman code unfortun variant arithmet code jpeg standard subject patent own ibm at t mitsubishi thu legal arithmet code licens compani the fair doctrin allow peopl implement test algorithm store imag dubiou best at short recommend peopl worri arithmet code space save great justifi potenti legal hassl in arithmet code imag exchang usenet there small chanc legal situat chang futur stai tune detail 13 doe loss accumul repeat compress decompress? it nice compress imag jpeg decompress manipul crop border recompress imag degrad lost initi unfortun thi is not the case in gener recompress alter imag lose lost time the best thing decompress imag recompress chang loss ident jpeg file even true current free jpeg softwar it's essenti problem accumul roundoff error if repeatedli compress decompress imag eventu degrad visibl chang first-gener output it take cycl visibl chang on thing to-do list accumul error avoid limit optimist in case guarante compress unmodifi full-color output djpeg origin qualiti set introduc loss even simpl chang crop border roundoff-error degrad if wonder pixel-block boundari move if crop multipl 16 pixel safe mighti limit capabl! the bottom jpeg format archiv storag transmiss imag intermedi format sequenc imag manipul step us lossless format ppm rle tiff work imag jpeg readi file asid avoid degrad save lot compress decompress time - 14 what rule thumb convert gif imag jpeg? as state earlier lose amount imag convert exist gif imag jpeg if origin full-color data gif better jpeg but save space gif work suggest maximum space save minimum loss qualiti the rule convert gif librari jpeg happi throw correspond gif chanc re-do convers higher qualiti set some gif better left gif explain 3 cartoon-type gif sixteen fewer color convert well you find jpeg file reason qualiti larger gif so check size experi suggest larg high-visual-qualiti gif best candid convers jpeg thei chew storag offer potenti save convert jpeg degrad don't wast time convert gif 100 kbyte also expect jpeg file convert gif small creat directli full-color origin to maintain imag qualiti convert file big straight-through jpeg file shoot 1 2 1 3rd size gif file 1 4th suggest earlier comparison mani peopl develop odd habit put larg constant-color border gif imag while useless free term storag cost gif file it not free jpeg file sharp border boundari creat visibl artifact ghost edg do favor crop border jpege if x window system xv's manual automat crop function painless cjpeg's default q set 75 appropri full-color input gif input q set 85 95 avoid imag degrad if appli smooth suggest higher q set color gif photograph complex artwork dither fool ey 256 color gif store if enlarg imag adjac pixel color normal size ey averag pixel produc illus intermedi color the troubl dither jpeg high-spatial-frequenc color nois jpeg compress nois well the jpeg file larger lower imag qualiti jpege origin full color imag to smooth gif imag compress smooth averag nearbi pixel approxim color thought process rid rapid color chang jpeg troubl appropri smooth avoid high q factor reduc size compress file obtain better-look output imag smooth with v4 free jpeg softwar product base simpl smooth capabl built try -smooth 10 convert gif valu 10 25 work well high-qualiti gif heavi-hand dither requir larger smooth factor if regular fine-scale pattern gif imag enlarg strong smooth definit call too larg smooth factor blur output imag if imag process wizard smooth separ filter program pnmconvol pbmplu packag howev cjpeg's built-in smoother lot faster pnmconvol the upshot cjpeg -qualiti 85 -smooth 10 good start point convert gif but care imag check set --------------------- for jpeg gener free jpeg softwar contact independ jpeg group jpeg-info uunet uu net -- tom lane organ independ jpeg group internet tgl bitnet tgl carnegi 