PNG-hom nta, daim ntawv thov thiab yog vim li cas rau lub chaw

Ib tug loj ua hauj lwm txojkev imposers qhov chaw tshiab yog ceev loading nplooj ntawv Browser. Txij li thaum tsawg heev tsim zoo li nws tsis yog tag nrho cov neeg yuav tsum nrhiav ib tug hais nruab nrab ntawm qhov zoo nkauj tsim nrog elegant graphics thiab cov kev ceev ntawm lub web kev pab. Yav tas los, nyob rau hauv thiaj li yuav txo tau qhov ceeb thawj ntawm cov dluab, cov developers ntawm qhov chaw siv los yog GIF, los yog JPG. Tam sim no ntau thiab ntau web designers siv cov dluab nyob hauv PNG hom. Ua ke, cia peb sim kom to taub yog vim li cas qhov no yog tshwm sim.

PNG-hom Vim li cas coined

Tsiaj ntawv, uas yog ib lub npe ntawm no hom ntawm kev kos duab, tsim los ntawm tus thawj tsiaj ntawv li nram qab no English lus: portable network graphics, uas muaj peev xwm muab txhais raws li "placeable graphics siv nyob rau hauv lub network." PNG-hom tau hais devised kom kov yeej lub disadvantages ntawm compression siv ib tug yooj yim algorithm GIF, uas maj mam pib los ua obsolete. Nyob rau hauv tas li ntawd, tej zaum nws yuav rau qee yam twg yuav siv los hloov cov ib tug ntau loj TIFF, siv mas rau editing.

Yuav ua li cas yog PNG-hom

Niaj hnub no lug siv ob versions ntawm lub algorithm. Nyob rau hauv lub yav tas los cov ntaub ntawv yog muaj ntaub ntawv muaj 8-ntsis xim palette, thiab nyob rau hauv lub thib ob - 24 ntsis. Duab nyob rau hauv PNG-8 hom ntawv, piv rau GIF-version txawv dog dig zoo degree ntawm compression thiab tsis muaj kev muaj peev xwm tsim animations. Txawm tias muaj tseeb hais tias xws li dluab yuav muaj ib tug tshaj plaws ntawm 256 cov xim, qhov no algorithm yog dav siv los tsim ib tug graphical ntawv nyeem, logos, dluab nrog cov npoo thiab cov dluab nrog gradient transparency. Nyob rau hauv tus neeg mob nyob qhov twg no yog tsis txaus, developers siv 24-ntsis PNG-hom, uas muaj ib tug ntau ntawm cov kev pab, xws li:

• Superior compression algorithm, uas thiaj li mus tsis muaj nuj nqis ib yam tsis zoo.
• Lub peev xwm siv alpha transparency muab 256 txawv muaj ntau seem ntawm transparency.
• Lub xub ntiag ntawm gamma kho, uas cia li kho cov brightness ntawm daim duab thaum uas ua si nyob rau hauv txawv kev pab cuam.
• Lub peev xwm siv txog 16,7 lab xim.

Tag nrho cov no tswj hauv daim ntawv thov PNG24 ua ke rau hlob tej duab muaj lub pob tshab feem ntawm drawings uas muaj ntau xim thiab ntse npoo ntawm daim duab.

txoj kev loj hlob qauv

Txawm tias muaj tseeb hais tias cov kis ntawm PNG-hom tseem tsis txaus los ntawm cov laus browsers, raws li zoo raws li tsis txaus thiab tsis tag them nyiaj yug ntawm no algorithm nta nyob rau hauv tshiab versions, PNG rau web graphics yog heev pheej. Piv nrog rau GIF nws muaj peb loj zoo: ib tug alpha channel, gamma kho thiab ob-dimensional interlacing (ib txoj kev hnyav zaub duab). Thiab piv nrog JPEG nws twb tsis muaj tsis zoo. Nco ntsoov tias lub PNG-hom yog invented los ntawm Lub ib hlis ntuj 4, 1995. Txij thaum ntawd los 18 xyoo dhau los, thiab nws los ua ib tug lead rau cov kev siv nyob rau hauv websites, GIF thawb mus rau hauv ob qhov chaw. Feem ntau cov kev cai graphics software (xws li MS Xim) hnub no saws nws raws li ib tug txheej txheem rau txuag cov ntaub ntawv "los ntawm lub neej ntawd". Tej zaum, yog hais tias tsis animation thiab cov quirks ntawm cov laus versions Internet Explorer, GIF muab txoj kev rau nws cov yeeb ncuab lawm.