O le a le Compression Leiloa?<\/h3>\n
O le fa’amalosi e leai se gau e fa’aitiitia ai le tele o faila e ala i le fa’ailoaina ma le fa’ate’aina o fa’amaumauga e aunoa ma le aveesea o so’o se fa’amatalaga. Pe a fa’apalapala, o le faila e tutusa lelei ma le ulua’i faila, e matua leai lava se gau i le lelei po’o le fa’amaoni o fa’amaumauga.<\/p>\n <\/div>\n <\/div>\n \n
Fa’afefea ona Gaioiina le Compression Leai<\/h3>\n
E fa’aogaina e le algorithms compression lossless auala eseese e fa’aitiitia ai le tele o faila a’o fa’amautinoa le toe fa’aleleia atoatoa o fa’amaumauga muamua. O nei metotia e su’esu’e ai mamanu, alaleo, ma fausaga i totonu o fa’amaumauga ina ia fa’aoga lelei e aunoa ma le leiloa o fa’amatalaga.<\/p>\n \n
Fa’ailoga Umi-Uumi (RLE)<\/h4>\n
E sui e le RLE fa’asologa o elemene fa’amaumauga tutusa (taufetuli) ma se tau e tasi ma le faitau. Mo se fa’ata’ita’iga, “AAAAAABBBCCCCC” ua avea ma “6A3B5C”, fa’aitiitia tele mo fa’amaumauga ma le tele o fa’asologa faifaipea.<\/p>\n
Original: WWWWWWWWWWBBBWWWWWWWWWWWWBBBWWWWWWWWWW\nCompressed: 10W3B12W3B10W<\/pre>\n <\/div>\n <\/div>\n \n\n\n <\/i>\n <\/div>\nHuffman Coding<\/h4>\n
O lenei metotia e tu’uina atu ai tulafono laiti e fesuisuia’i umi i mataitusi e fa’aofi, fa’atasi ai ma fa’ailoga pupuu mo mataitusi masani. O lenei faiga fa’afuainumera e fa’amalieina ai le fa’ailoga e fa’atatau i le fa’asoa fa’asologa o uiga.<\/p>\n
\n Faataitaiga:<\/strong>\nFrequent character 'e': 101\nLess frequent 'z': 1010101011<\/pre>\n <\/div>\n <\/div>\n \n\n\n <\/i>\n <\/div>\nLZ77 & LZ78 Algorithms<\/h4>\n
O nei metotia fa’avae lomifefiloi e sui ai fa’amatalaga fa’asolosolo fa’atasi ma fa’asino i se kopi e tasi ua uma ona iai i le vaitafe e le’i fa’apipi’iina. Latou te faia le fa\u02bbavae mo fa\u02bbasalalauga lauiloa e pei o le ZIP ma le GIF.<\/p>\n
\n Faataitaiga:<\/strong>\nInstead of storing \"compression compression\"\nStore \"compression [pointer to earlier instance]\"<\/pre>\n <\/div>\n <\/div>\n \n\n\n <\/i>\n <\/div>\nDeflate Algorithm<\/h4>\n
Fa\u02bbatasia le LZ77 ma le Huffman coding, Deflate e maua ai le fa\u02bbamalosi lelei ma le saoasaoa lelei. O lo’o fa’aogaina i le ZIP, PNG, ma le HTTP compression (gzip), ma avea ai ma se tasi o algorithms sili ona fa’aogaina.<\/p>\n
\n Talosaga:<\/strong>\n\n
- ZIP archives<\/li>\n
- ata PNG<\/li>\n
- HTTP compression (gzip)<\/li>\n <\/ul>\n <\/div>\n <\/div>\n \n
\n\n <\/i>\n <\/div>\nFa’ailoga Fa’ailoga<\/h4>\n
O lenei metotia o lo\u02bbo fa\u02bbatusalia ai se fe\u02bbau e pei o se numera o numera i le va o le 0 ma le 1. E mafai ona ausia fa\u02bbatusatusaga fa\u02bbamalosi e latalata i le fa\u02bbatapula\u02bbaina o le entropy fa\u02bbata\u02bbita\u02bbiga, e sili ona lelei mo nisi ituaiga o fa\u02bbamaumauga.<\/p>\n
\n Tulaga lelei:<\/strong>\nE mafai ona fa’apipi’i vaega ninii i le fa’ailoga, e sili atu le fa’amalosi nai lo Huffman mo le tele o fa’apogai.<\/p>\n <\/div>\n <\/div>\n \n
\n\n <\/i>\n <\/div>\nDelta Encoding<\/h4>\n
Nai lo le teuina o tulaga taua, delta encoding e teuina eseesega i le va o tulaga taua. E fa’apitoa lea mo fa’amaumauga e tutusa tulaga taua, pei o fa’ata’ita’iga fa’alogo po’o faitauga fa’alogo.<\/p>\n
\n Faataitaiga:<\/strong>\nOriginal: 105, 107, 106, 110, 108\nDelta: 105, +2, -1, +4, -2<\/pre>\n <\/div>\n <\/div>\n <\/div>\n \nFa’asologa masani o faila e leai se leiloa<\/h3>\n
\n\n\n <\/i>\nFa’amaumauga<\/h4>\n <\/div>\n
\nZIP<\/div>\nRAR<\/div>\n7Z<\/div>\nGZIP<\/div>\nBZIP2<\/div>\nTAR<\/div>\n <\/div>\n <\/div>\n \n\n\n <\/i>\nAta<\/h4>\n <\/div>\n
\nPNG<\/div>\nTIFF<\/div>\nBMP<\/div>\nGIF<\/div>\nWebP (le leiloa)<\/div>\n <\/div>\n <\/div>\n \n\n\n <\/i>\nLeo<\/h4>\n <\/div>\n
\nFLAC<\/div>\nALAC<\/div>\nWAV<\/div>\nAPE<\/div>\nWavPack<\/div>\n <\/div>\n <\/div>\n <\/div>\n <\/div>\n <\/section>\n \n \n\n Fa’amatalaina le Compression Lossy<\/h2>\n \n
\n\n\n <\/i>\n <\/div>\n\nO le a le Lossy Compression?<\/h3>\n
O le fa’aletonu fa’amalosi e fa’aitiitia ai le tele o faila e ala i le fa’amutaina tumau o fa’amatalaga fa’apitoa, ae maise fa’amatalaga fa’aletonu po’o fa’amatalaga le taua. O le faila decompressed e ese mai le uluai, ae o eseesega ua mamanuina e faigata pe le mafai e tagata ona iloa i lalo o tulaga masani.<\/p>\n <\/div>\n <\/div>\n \n
Fa’afefea ona galue le Compression Lossy<\/h3>\n
O le fa’aliga fa’aletonu e maua ai le maualuga maualuga o fa’atusatusaga fa’amalosi e ala i le faia o fa’ai’uga fa’atatau e uiga i fa’amaumauga e lafoa’i. O nei algorithms e fa’aogaina ai le malamalama e uiga i le va’aiga a le tagata-mea e mafai ma e le mafai e o tatou mata ma taliga ona iloa-e aveese fa\u02bbamatalaga i auala e fa\u02bbaitiitia ai le a\u02bbafiaga o le lelei.<\/p>\n \n
\n\n\n <\/i>\n <\/div>\nSuia Coding<\/h4>\n
O lenei metotia e suia ai fa\u02bbamatalaga mai le tasi vaega (pei o le fa\u02bbafanua) i le isi (pei o taimi) lea e mafai ai ona fa\u02bbaoga lelei le fa\u02bbamalosi. O le Discrete Cosine Transform (DCT) o lo\u02bbo fa\u02bbaaogaina i le JPEG o se fa\u02bbata\u02bbita\u02bbiga sili.<\/p>\n
\n Fa’agasologa:<\/strong>\n\n
- Su’e poloka ata i vaega fa’atele<\/li>\n
- Fa’ato’a fa’afuainumera vaega fa’aautu maualuga<\/li>\n
- O mata o le tagata e itiiti le maaleale i nei alaleo<\/li>\n <\/ul>\n <\/div>\n <\/div>\n \n
\n\n <\/i>\n <\/div>\nQuantization<\/h4>\n
O le fa’atusatusaga e fa’aitiitia ai le sa’o o fa’amaumauga. O lo’o fa’afanua ai le tele o tau fa’aoga i se seti la’ititi o fa’atauga, fa’aitiitia lelei le aofa’i o pusi e mana’omia e fa’atusa ai fa’amaumauga.<\/p>\n
\n Faataitaiga:<\/strong>\nOriginal values: 4.13, 4.28, 4.97, 4.02\nQuantized to: 4, 4, 5, 4<\/pre>\n <\/div>\n <\/div>\n \n\n\n <\/i>\n <\/div>\nFa’ata’ita’iga a le Psychoacoustic<\/h4>\n
E fa’aogaina i le fa’alogo leo, o lenei metotia e fa’aogaina ai tapula’a o le fa’alogo a tagata. E iloa ai po’o fea vaega leo e mafai ona aveese e aunoa ma le afaina o le lelei o le leo.<\/p>\n
\n Manatu Autu:<\/strong>\n\n
- Ufiufi fa’alogo: Ufiufi leotele leo sili atu le leo<\/li>\n
- Ma’ale’ale fa’alava: E sili ona lelei le fa’alogo a tagata i alaleo vaeluagalemu<\/li>\n
- Ufiufi fa’aletino: E mafai e leo ona ufiufi isi e tutupu i se taimi lata mai a’o le’i mae’a<\/li>\n <\/ul>\n <\/div>\n <\/div>\n \n
\n\n <\/i>\n <\/div>\nFa’ailoga Fa’ailoga<\/h4>\n
E tutusa ma le fa\u02bbata\u02bbita\u02bbiga o le psychoacoustic ae mo fa\u02bbamatalaga va\u02bbaia, o lenei auala e aveese ai fa\u02bbamatalaga e tau le iloa e mata o le tagata, aemaise lava i fa\u02bbamatalaga maualuga ma fesuiaiga o lanu.<\/p>\n
\n Talosaga:<\/strong>\nFa’aoga ile JPEG, MPEG, ma isi tulaga fa’apipi’i va’aia e fa’amuamua ai fa’amatalaga taua.<\/p>\n <\/div>\n <\/div>\n \n
\n\n <\/i>\n <\/div>\nTaui Lafo<\/h4>\n
Vitio fa’apipi’i auala e fa’aogaina ai le fa’aagaga fa’aletino e ala i le fa’avasegaina o eseesega i va o fa’avaa nai lo fa’avaa atoa ta’itasi. E na’o suiga mai le tasi fa’avaa i le isi fa’apolokalame atoa.<\/p>\n
\n Fa’agasologa:<\/strong>\n\n
- Teu fa’agata “fa’ava’ava’a” (I-frames) i lea taimi ma lea taimi<\/li>\n
- Mo isi fa’avaa, teu na’o eseesega (P-frames) po’o eseesega fa’asinoala (B-frames)<\/li>\n
- I’uga i le fa’aitiitia tele o faila mo le viti\u014d<\/li>\n <\/ul>\n <\/div>\n <\/div>\n \n
\n\n <\/i>\n <\/div>\nChroma Subsampling<\/h4>\n
O lenei metotia e fa\u02bbaitiitia ai fa\u02bbamatalaga lanu nai lo fa\u02bbamatalaga susulu, fa\u02bbaaogaina le sili atu ona maaleale mata o le tagata i le susulu nai lo le eseesega o lanu.<\/p>\n
\n Fa’asologa masani:<\/strong>\n\n
- 4:4:4 – Leai se subsampling (lanu atoa)<\/li>\n
- 4:2:2 – afa fa’alava fa’alava fa’ai’uga lanu<\/li>\n
- 4:2:0 – Fa’afa’afa fa’alava ma fa’alava fa’ai’uga lanu<\/li>\n <\/ul>\n <\/div>\n <\/div>\n <\/div>\n \n
Fa’asologa masani o faila faila<\/h3>\n
\n\n\n <\/i>\nAta<\/h4>\n <\/div>\n
\nJPEG<\/div>\nWebP (gaimau)<\/div>\nJPEG 2000<\/div>\nHEIF<\/div>\nAVIF<\/div>\n <\/div>\n <\/div>\n \n\n\n <\/i>\nLeo<\/h4>\n <\/div>\n
\nMP3<\/div>\nAAC<\/div>\nVorbis<\/div>\nOpus<\/div>\nWMA<\/div>\n <\/div>\n <\/div>\n \n\n\n <\/i>\nVitio<\/h4>\n <\/div>\n
\nH.264<\/div>\nH.265<\/div>\nVP9<\/div>\nAV1<\/div>\nWebM<\/div>\n <\/div>\n <\/div>\n <\/div>\n <\/div>\n <\/section>\n \n \n\n Talosaga Fa’atino ma Tulaga Fa’aoga<\/h2>\n \n
\n\n\n\n <\/i>\n <\/div>\nAta fa’atekinolosi<\/h3>\n <\/div>\n
\nFa’amatega e leai se gau<\/h4>\n
\n
- Fa’asaoina le fa’asologa o le RAW mo tagata pueata fa’apolofesa<\/li>\n
- Fa’amaumauga-lelei le teuina o ata taua<\/li>\n
- Ata e mana’omia ai le tele o le fa’agaioiga po’o le fa’atonutonu<\/li>\n
- PNG fa’atulagaina mo ata fa’atusa ma tusitusiga po’o pito ma’ai<\/li>\n <\/ul>\n \n
Lossy Compression<\/h4>\n
\n
- JPEG mo ata o aso uma ma fefa\u02bbasoaa\u02bbi i luga o le upega tafa\u02bbilagi<\/li>\n
- Fa’atupuina ata mo ata ma mua’i va’aiga<\/li>\n
- Fa’asalalauga fa’aagafesootai fa’apipi’i pe a fa’atapula’aina le tele<\/li>\n
- Imeli fa’apipi’i ma tusi talosaga fe’au<\/li>\n <\/ul>\n \n
\n Fa’ata’ita’iga Sili:<\/strong> Pu’e i le RAW po’o le leai se fa’asologa, faia ni fa’amatalaga leiloa mo le fefa’asoaa’i, fa’amaumau matai leiloa mo le fa’amaumauga.\n <\/div>\n <\/div>\n <\/div>\n \n\n\n\n <\/i>\n <\/div>\n