Goにおける画像ファイル処理 / golang.tokyo #19

ImageFlux
Goにおける画像ファイル処理
Golang.Tokyo #19 Talks.2 / 2018-11-03

Transcript

1. (Pחֶֽ׷歗⫷ؿ؋؎ٕⳢ椚 )BSVLBTBO
   
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   ˋ
    Gopher images were created by Takuya Ueda (https://twitter.com/tenntenn). Licensed under the Creative Commons 3.0 Attributions license.
2. )BSVLBTBO
   
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   4IVOTVLF ؾؙءـ吳䒭⠓爡
   *NBHF'MVY✲噟鿇鿇ꞿ
   ؾؙءـذؙظٗآ٦ؤ吳䒭⠓爡㛁遤䕵㆞
   䎃倜⼼Ⰵ爡
   歗⫷㢌䳔⟃㢩חכծOHJOYծر٦ةⴓ匿㛇湍זו
3. 63-
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   4
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4. *NBHF'MVYה(P ˖ *NBHF'MVYך؝،؝ٝه٦طٝزך㢳ֻכ(Pד㹋鄲ׁ׸גְ׷
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   ˖ 넝鸞ַא㸜Ⰻז)551؟٦غ㹋鄲ծ$ך垥彊ٓ؎ـٓٔㄎן⳿׃זוָ〳腉׌׏׋ ֿהָ㣐ֹז椚歋
   ˖ *NBHF'MVYךקרⰋגך؝ٝه٦طٝزכ)551؟٦غה׃ג㹋鄲
 崧遤ךٙ٦سד鎉ֲהو؎ؙٗ؟٦ؽأ
5. *NBHF
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6. *NBHF
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7. &OE
   VTFS %JTQMBZ *OQVU .FEJB Electromagnetic wave 8IBU
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8. +1&( *NBHF
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9. +1&( +1&(+'*'
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   رؿ؋ؙزהז׏גְ׋ؿؓ٦وحز׾垥彊⻉׃׋׮ך
   &9*'
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   MF
   TUSVDUVSF &9*'
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10. R +1&( IUUQTDPNNPOTXJLJNFEJBPSHXJLJ'JMF$$%QOH 㛇劤涸ז،ٕ؞ٔؤي
    
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11. 1/( 1/(
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    1/(כ[MJC
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12. 8FC1 8FC1
    1PSUBCMF
    /FUXPSL
    (SBQIJDT 71ךؗ٦ؿٖ٦ي歗⫷׾3*''؝ٝذشח鯹ׇ׋歗⫷䕎䒭
    +1&(״׶׮㣐ⴓ倜׃ְךדծ넝ㅷ颵ծ넝㖇簭׾ֲ׋׏גְ׷
    ⹛歗䕎䒭׾ك٦أה׃גְ׷׋׭ծ563
    #5䕎䒭ך:67ؕٓ٦ٌرٕ׾⢪ֲ
    +1&(ך:$C$Sהכ⦼㚖ָ殯ז׷
    ؟ـ؟ٝفؚٖٔٝءؔכ׃ַ؟ه٦ز׃גְזְךד+1&(״׶׮רװֽ׷ ֿהָ㢳ְ
13. *NBHF
    1SPDFTTJOH
    JO
    (P
14. JNBHF*NBHF type Image interface { // ը૾ͷΧϥʔϞσϧΛฦ͢ ColorModel() color.Model // ը૾ͷBoundsΛฦ͢ Bounds() Rectangle // (x, y)ϐΫηϧͷ৭Λฦ͢ɻAt(0,0)͸Ұ൪ࠨ্ɺ
 // At(Bounds().Max.X-1, Bounds().Max.Y-1)͸Ұ൪ӈԼΛฦ͢ɻ At(x, y int) color.Color } 歗⫷ر٦ةⰟ鸐ך؎ٝة٦ؿؑ٦أ
    "U Y
    Z ׾欽ְ׷ֿהדծぐ歗稆ך葿׾《䖤דֹ׷
    DPMPS$PMPSכ3(#葿瑞꟦ח㢌䳔׃ג葿׾《䖤דֹ׷
15. JNBHF:$C$S type YCbCr struct { Y, Cb, Cr []uint8 YStride int CStride int SubsampleRatio YCbCrSubsampleRatio Rect Rectangle } :ծ$Cծ$S׉׸׊׸ךꂁ⴨ח؝ٝه٦طٝز׀הךر٦ةָろת׸גְ׷
    1MBOFS 
 :$C$S4VCTBNQMF3BUJPכ؟ـ؟ٝفؚٔٝ嫰׾㹀纏ׅ׷ Y Y Y Y Y Y Y Y 0 … Y Y Y Cb Cb Cb Cb Cb Cb Cb 0 0 … Cb Cb Cb Cr Cr Cr Cr Cr Cr Cr 0 0 … Cr Cr Cr :4USJEF $4USJEF
16. JNBHF/3(#" type NRGBA struct { Pix []uint8 Stride int Rect Rectangle } 3(#"ָ♧אךꂁ⴨ח鑥׭׵׸גְ׷
    1BDLFE
    3(#"
    3(#"ה/3(#"ך麩ְכ1SFNVMUJQMJFE
    "MQIBה/PO1SFNVMUJQMJFE
    "MQIBך麩ְ RGBA R G B A R G B A 0 0 R G B … 4USJEF
17. 歗⫷غحؿ؋הأزٓ؎س R G B A R G B A R G B A R G B A 0 0 R G B A R G B A R G B A R G B A 0 0 R G B A R G B A R G B A R G B A 0 0 R G B A R G B A R G B A R G B A 0 0 R G B A R G B A R G B A R G B A 0 0 R G B A R G B A R G B A R G B A 0 0 R G B A R G B A R G B A R G B A 0 0 R G B A R G B A R G B A R G B A 0 0 8JEUI 4USJEF 歗⫷غحؿ؋כ剑黝⻉ך׋׭4USJEF؟؎ؤד،ٓ؎ًٝٝزׁ׸גְ׷
    Y
    Z
    ָ妜׃ְהֹכ1JY< Z3FDU.JO: 4USJEF
    
    Y3FDU.JO9 >
    
18. *NBHF'MVY
    1SPDFTTJOH
    JO
    (P
19. JNBHFVY4DBO-JOF3FBEFS type ScanLineReader interface { io.Closer // Config returns the configurations of the image planes. Config() *Config // ReadScanLines reads scan lines into the p for each image component. it // reads up to len(p[0]) at once and returns number of bytes read and any // error. When the image is YCbCr 4:2:0, // ReadScanLines(p) returns // p[0]: read scan lines of the Y component. // p[1]: read scan lines of the Cb component. // p[2]: read scan lines of the Cr component. // // ReadScanLines returns an error in the same manner of io.Reader. ReadScanLines(ctx context.Context, p [][]byte) (n int, err error) // ReadLen returns the minimum buffer length that needs to read from this. ReadLen() (n int) }
20. 3FBE4DBO-JOFT 㛇劤涸חכ如⯋ꂁ⴨ח䭁䓸׃׋JP3FBEFS
    ؝ٝذؗأز׾欽ְג铣׫鴥׫ךة؎ي،ؐزծٍؗٝإָٕדֹ׷ // ReadScanLines reads scan lines into the p for each image component… ReadScanLines(ctx context.Context, p [][]byte) (n int, err error) p[0]: Y Y Y Y Y Y Y Y … p[1]: Cb Cb Cb Cb Cb Cb Cb Cb … p[2]: Cr Cr Cr Cr Cr Cr Cr Cr … +1&(
    %FDPEFS p[0]: R G B A R G B A … 1/(
    %FDPEFS
21. 4DBO-JOF3FBEFS׾㹋鄲׃׋؝ٝه٦طٝز ׾אזֺさ׻ׇ׷
    func NewDecoder(src io.ReadCloser, cfg Config) (imageflux.ScanLineReader, error) ر؝٦تכJP3FBEFSַ׵غ؎ز⴨׾「ֽ《׏ג歗⫷׾ر؝٦سׅ׷
22. 4DBO-JOF3FBEFS׾㹋鄲׃׋؝ٝه٦طٝز ׾אזֺさ׻ׇ׷
    func NewScaler(src imageflux.ScanLineReader, cfg Config) (imageflux.ScanLineReader, error) Ⰵ⸂הז׷4DBO-JOF3FBEFS׾䒷侧חה׏גծ⳿⸂׾铣׫鴥׬׋׭ך4DBO-JOF3FBEFS׾鵤ׅ
    ر؝٦تַ׵ؒٝ؝٦تתדػ؎فٓ؎ٝ׾⡲׷ֿהח״׏ג歗⫷㢌䳔׾遤ֲ
23. 4DBO-JOF3FBEFS׾㹋鄲׃׋؝ٝه٦طٝز ׾אזֺさ׻ׇ׷
    func Write(ctx context.Context, dst io.Writer, src imageflux.ScanLineReader) error ؒٝ؝٦تכ4DBO-JOF3FBEFS׾「ֽ《׏גؒٝ؝٦س穠卓׾JP8SJUFSח剅ֹ鴥׬
24. JPEG PNG GIF WebP RGB Compositing Scaling Clipping Color Converter JPEG PNG GIF WebP 4DBO-JOF3FBEFS׾㹋鄲׃׋؝ٝه٦طٝز ׾אזֺさ׻ׇ׷
    +1&(׾+1&(ךתתٔ؟؎ؤׅ׷הֹכ葿瑞 ꟦ך㢌䳔כ遤׻זְ ٥
    
25. JPEG PNG GIF WebP RGB Compositing Scaling Clipping Color Converter JPEG PNG GIF WebP 4DBO-JOF3FBEFS׾㹋鄲׃׋؝ٝه٦طٝز ׾אזֺさ׻ׇ׷
    +1&(׾+1&(ךתתٔ؟؎ؤׅ׷הֹכ葿瑞 ꟦ך㢌䳔כ遤׻זְ
    ػ؎فٓ؎ٝך穄畭כ♧菙涸זJP3FBEFSծ JP8SJUFSד㹋鄲ׁ׸גְ׷ךדծIUUQ$MJFOU װIUUQ3FTQPOTF8SJUFSהאזּֿהד歗⫷㢌 䳔فٗؗء׾⡲׷ֿהָדֹ׷ ٥
    ٥
    IUUQ$MJFOU IUUQ3FTQPOTF8SJUFS
26. JPEG PNG GIF WebP RGB Compositing Scaling Clipping Color Converter JPEG PNG GIF WebP 4DBO-JOF3FBEFS׾㹋鄲׃׋؝ٝه٦طٝز ׾אזֺさ׻ׇ׷
    ؔ٦غ٦ٖ؎さ䧭׾遤ֲꥷכ3(#葿瑞꟦ח㢌 䳔׃גַ׵さ䧭׾遤ֲ ٥
    
27. *NBHF'MVYחֶֽ׷歗⫷㢌䳔 ˖ ػ؎فٓ؎ٝⳢ椚ח״׏גغحؿ؋؟؎ؤ׾剑㼭⻉דֹ׷
    ˖ 歗⫷ؿ؋؎ٕךر؝٦سծؒٝ؝٦سחכ垥彊涸ז$ٓ؎ـٓٔ׾欽ְ׷
 MJCKQFHUVSCPծMJCQOHծHJJCזו
    ˖ 葿瑞꟦ך㢌䳔ծؔ٦غ٦ٖ؎さ䧭כأٍؗٝٓ؎ٝ׀החתה׭ג遤ֲ
 1MBO،إٝـٔ׾欽ְג4*.%剑黝⻉
    ˖ *NBHF'MVYך椚䟝
    ـٓؐؠָ邌爙דֹ׷歗⫷כׅץג㢌䳔דֹ׷
 垥彊鋉呓ה׃ג姻׃ֻג׮ـٓؐؠכ姻׃ֻ䪔׻זְֿהָ֮׷
 㸣Ⰻח㠨׸׋歗⫷ד׮ـٓؐؠכז׿ַ姻׃ֻ邌爙׃ג׃תֲֿהָ֮׷
    ˖ ؕٓ٦فٗؿ؋؎ٕזו歗⫷ر٦ة⟃㢩׮䪔ֲֿהָדֹ׷
28. ؕٓ٦فٗؿ؋؎ٕך䪔ְ ˖ +1&(ծ1/(ծ8FC1חכ*$$䕎䒭ךؕٓ٦فٗؿ؋؎ٕ׾㙵׭鴥׬ֿהָדֹ׷
    ˖ -JUUMF
    $.4׾ⵃ欽׃גؕٓ٦فٗؿ؋؎ٕ׾欽ְ׋葿瑞꟦ך㢌䳔׾㹋植
    ˖ (PךJNBHFחろת׸גְ׷ر؝٦تծؒٝ؝٦تכؕٓ٦فٗؿ؋؎ٕ׾؟ه٦ ز׃גְזְ
    ˖ JNBHFKQFHװJNBHFQOHד*$$ךغ؎شָٔ《䖤דֹ׷״ֲח׃גֶֻה葺ְַ ׮
29. תה׭ ˖ *NBHF'MVYך歗⫷㢌䳔Ⳣ椚כ(Pד剅ַ׸גְ׷
    ˖ 歗⫷Ⳣ椚荈⡤כ׌ְ׋ְ$ד㹋鄲ׁ׸גְ׷
    ˖ ぐٓ؎ـٓٔך؎ٝة٦ؿؑ٦أ׾(Pד㹋鄲ׅ׷ֿהד笺뜧ח㹋鄲דֹ׷
    ˖ JP3FBEFSהJP8SJUFS׾؎ٝة٦ؿؑ٦أה׃ג⢪׏גֶֻה)551האז־׋׶ ؿ؋؎ٕה籬־׋׶דֹג⤑ⵃ