Gulp PNG-Optimierung verbessern Aufgabe

Question

Dies ist Quelle PNG mit Transparenz: http://i.imgur.com/7m0zIBp.png (13.3kB)

• optimiert mit compresspng.com: http://i.imgur.com/DHUiLuO.png (5.4kB)
• optimiert mit tinypng.com: http://i.imgur.com/rEE2hzg.png (5,6 kb)
• optimiert gulp-imagemin + imagemin-pngquant: http://i.imgur.com/OTqI6lK.png (6,6 kb)

Wie Sie sehen können, sind Online-Tools besser als Gulp. Gibt es eine Möglichkeit, die PNG-Optimierung mit Gulp zu verbessern?

Nur für den Fall, hier ist meine schluck Aufgabe:

gulp.task('images', function() { 
    return gulp.src('frontend/images/*') 
    .pipe(imagemin({ 
     progressive: true, 
     use: [pngquant()] 
    })) 
    .pipe(gulp.dest('public/images')); 
}); 

Answer 1

können Sie prüfen, was die verschiedenen Algorithmen mithilfe von ImageMagicks identify -verbose Werkzeug gemacht haben, wie diese

identify -verbose com.png > com.txt 
identify -verbose tin.png > tin.txt 
identify -verbose gulp.png > gulp.txt 

und dann die Ausgänge vergleichen - ich opendiff auf dem Mac verwenden. Sie werden das sehen, wenn Sie com.txt (compresspng) im Vergleich zu gulp.txt

vergleichen und dies, wenn Sie vergleichen winzig (tinypng) im Vergleich zu gulp.txt

Der Unterschied ist in der Anzahl der Farben beibehalten - Schluck verwendet 94 Farben, compresspng verwendet 66, und kleine Anwendungen 53.

Falls Sie oder jemand anderes, andere Aspekte zu vergleichen möchte, paste ich in den 3 o utoput Dateien unten als Referenz:

Schluck.txt

Image: gulp.png 
    Format: PNG (Portable Network Graphics) 
    Mime type: image/png 
    Class: DirectClass 
    Geometry: 560x290+0+0 
    Units: Undefined 
    Type: PaletteAlpha 
    Endianess: Undefined 
    Colorspace: sRGB 
    Depth: 8-bit 
    Channel depth: 
    red: 8-bit 
    green: 8-bit 
    blue: 8-bit 
    alpha: 8-bit 
    Channel statistics: 
    Pixels: 162400 
    Red: 
     min: 1 (0.00392157) 
     max: 245 (0.960784) 
     mean: 110.922 (0.434989) 
     standard deviation: 104.067 (0.408106) 
     kurtosis: -1.74946 
     skewness: 0.208663 
     entropy: 0.3477 
    Green: 
     min: 40 (0.156863) 
     max: 245 (0.960784) 
     mean: 124.973 (0.490091) 
     standard deviation: 61.139 (0.239761) 
     kurtosis: -1.32326 
     skewness: 0.222376 
     entropy: 0.330503 
    Blue: 
     min: 113 (0.443137) 
     max: 244 (0.956863) 
     mean: 170.131 (0.667179) 
     standard deviation: 53.7786 (0.210897) 
     kurtosis: -1.86628 
     skewness: 0.233095 
     entropy: 0.346704 
    Alpha: 
     min: 0 (0) 
     max: 255 (1) 
     mean: 197.075 (0.772845) 
     standard deviation: 106.443 (0.417423) 
     kurtosis: -0.298155 
     skewness: 1.3014 
     entropy: 0.157855 
    Image statistics: 
    Overall: 
     min: 0 (0) 
     max: 255 (1) 
     mean: 115.988 (0.454854) 
     standard deviation: 84.8383 (0.332699) 
     kurtosis: -0.730342 
     skewness: 0.117783 
     entropy: 0.295691 
    Alpha: srgba(76,105,113,0) #4C697100 
    Colors: 94 
    Histogram: 
     660: ( 1, 40,117,255) #012875 srgba(1,40,117,1) 
     8: ( 1, 58,131,255) #013A83 srgba(1,58,131,1) 
     4: ( 1, 66,138,255) #01428A srgba(1,66,138,1) 
     6: ( 1, 75,145,255) #014B91 srgba(1,75,145,1) 
     2: ( 1, 84,152,255) #015498 srgba(1,84,152,1) 
     4: ( 1, 93,159,255) #015D9F srgba(1,93,159,1) 
     3: ( 1,102,166,255) #0166A6 srgba(1,102,166,1) 
     6: ( 1,111,173,255) #016FAD srgba(1,111,173,1) 
     4: ( 1,119,180,255) #0177B4 srgba(1,119,180,1) 
     4: ( 1,128,187,255) #0180BB srgba(1,128,187,1) 
     1: ( 1,137,194,255) #0189C2 srgba(1,137,194,1) 
     20: ( 1,146,201,255) #0192C9 srgba(1,146,201,1) 
     5: ( 1,155,208,255) #019BD0 srgba(1,155,208,1) 
     3: ( 1,163,215,255) #01A3D7 srgba(1,163,215,1) 
     5: ( 1,172,222,255) #01ACDE srgba(1,172,222,1) 
    59271: ( 1,181,229,255) #01B5E5 srgba(1,181,229,1) 
     91: ( 1,181,229,143) #01B5E58F srgba(1,181,229,0.560784) 
     80: ( 1,181,229,224) #01B5E5E0 srgba(1,181,229,0.878431) 
     79: ( 1,181,229, 1) #01B5E501 srgba(1,181,229,0.00392157) 
     66: ( 1,181,229, 64) #01B5E540 srgba(1,181,229,0.25098) 
     61: ( 1,181,229, 16) #01B5E510 srgba(1,181,229,0.0627451) 
     54: ( 1,181,229, 36) #01B5E524 srgba(1,181,229,0.141176) 
     50: ( 1,181,229, 99) #01B5E563 srgba(1,181,229,0.388235) 
     46: ( 1,181,229,168) #01B5E5A8 srgba(1,181,229,0.658824) 
     46: ( 1,181,229, 9) #01B5E509 srgba(1,181,229,0.0352941) 
     45: ( 1,181,229, 4) #01B5E504 srgba(1,181,229,0.0156863) 
     39: ( 1,181,229,195) #01B5E5C3 srgba(1,181,229,0.764706) 
     32: ( 1,181,229, 25) #01B5E519 srgba(1,181,229,0.0980392) 
     30: ( 1,181,229,120) #01B5E578 srgba(1,181,229,0.470588) 
     29: ( 1,181,229, 80) #01B5E550 srgba(1,181,229,0.313725) 
     29: ( 1,181,229, 49) #01B5E531 srgba(1,181,229,0.192157) 
     4: (15, 41,118,255) #0F2976 srgba(15,41,118,1) 
     64: (16,185,230,255) #10B9E6 srgba(16,185,230,1) 
     4: (30, 42,119,255) #1E2A77 srgba(30,42,119,1) 
     40: (32,189,231,255) #20BDE7 srgba(32,189,231,1) 
     3: (44, 43,119,255) #2C2B77 srgba(44,43,119,1) 
     46: (47,193,232,255) #2FC1E8 srgba(47,193,232,1) 
     7: (59, 44,120,255) #3B2C78 srgba(59,44,120,1) 
     281: (62,197,233,255) #3EC5E9 srgba(62,197,233,1) 
     3: (73, 45,121,255) #492D79 srgba(73,45,121,1) 
    35876: (76,105,113, 0) #4C697100 srgba(76,105,113,0) 
     29: (77,201,234,255) #4DC9EA srgba(77,201,234,1) 
     1: (88, 46,122,255) #582E7A srgba(88,46,122,1) 
     39: (93,205,235,255) #5DCDEB srgba(93,205,235,1) 
     5: (102, 47,123,255) #662F7B srgba(102,47,123,1) 
     24: (108,209,236,255) #6CD1EC srgba(108,209,236,1) 
     18: (117, 48,124,255) #75307C srgba(117,48,124,1) 
     267: (123,213,237,255) #7BD5ED srgba(123,213,237,1) 
     3: (131, 49,124,255) #83317C srgba(131,49,124,1) 
     27: (138,217,237,255) #8AD9ED srgba(138,217,237,1) 
     2: (145, 50,125,255) #91327D srgba(145,50,125,1) 
     28: (154,221,238,255) #9ADDEE srgba(154,221,238,1) 
     4: (160, 51,126,255) #A0337E srgba(160,51,126,1) 
     16: (169,225,239,255) #A9E1EF srgba(169,225,239,1) 
     16: (174, 52,127,255) #AE347F srgba(174,52,127,1) 
     202: (184,229,240,255) #B8E5F0 srgba(184,229,240,1) 
     41: (199,233,241,255) #C7E9F1 srgba(199,233,241,1) 
     2: (203, 54,128,255) #CB3680 srgba(203,54,128,1) 
     43: (215,237,242,255) #D7EDF2 srgba(215,237,242,1) 
     2: (216, 55,129,195) #D83781C3 srgba(216,55,129,0.764706) 
     3: (218, 55,129,255) #DA3781 srgba(218,55,129,1) 
     49: (230,241,243,255) #E6F1F3 srgba(230,241,243,1) 
    53788: (232, 56,130,255) #E83882 srgba(232,56,130,1) 
     77: (232, 56,130, 99) #E8388263 srgba(232,56,130,0.388235) 
     72: (232, 56,130, 16) #E8388210 srgba(232,56,130,0.0627451) 
     71: (232, 56,130,143) #E838828F srgba(232,56,130,0.560784) 
     69: (232, 56,130,224) #E83882E0 srgba(232,56,130,0.878431) 
     65: (232, 56,130, 64) #E8388240 srgba(232,56,130,0.25098) 
     62: (232, 56,130,195) #E83882C3 srgba(232,56,130,0.764706) 
     52: (232, 56,130, 36) #E8388224 srgba(232,56,130,0.141176) 
     52: (232, 56,130, 4) #E8388204 srgba(232,56,130,0.0156863) 
     52: (232, 56,130, 1) #E8388201 srgba(232,56,130,0.00392157) 
     46: (232, 56,130, 9) #E8388209 srgba(232,56,130,0.0352941) 
     34: (232, 56,130, 80) #E8388250 srgba(232,56,130,0.313725) 
     33: (232, 56,130,168) #E83882A8 srgba(232,56,130,0.658824) 
     27: (232, 56,130, 25) #E8388219 srgba(232,56,130,0.0980392) 
     26: (232, 56,130,120) #E8388278 srgba(232,56,130,0.470588) 
     22: (232, 56,130, 49) #E8388231 srgba(232,56,130,0.192157) 
     57: (233, 68,137,255) #E94489 srgba(233,68,137,1) 
     34: (234, 80,144,255) #EA5090 srgba(234,80,144,1) 
     62: (234, 91,151,255) #EA5B97 srgba(234,91,151,1) 
     402: (235,103,159,255) #EB679F srgba(235,103,159,1) 
     51: (236,115,166,255) #EC73A6 srgba(236,115,166,1) 
     35: (237,127,173,255) #ED7FAD srgba(237,127,173,1) 
     34: (238,139,180,255) #EE8BB4 srgba(238,139,180,1) 
     43: (239,151,187,255) #EF97BB srgba(239,151,187,1) 
     44: (239,162,194,255) #EFA2C2 srgba(239,162,194,1) 
     56: (240,174,201,255) #F0AEC9 srgba(240,174,201,1) 
     38: (241,186,208,255) #F1BAD0 srgba(241,186,208,1) 
     58: (242,198,216,255) #F2C6D8 srgba(242,198,216,1) 
     41: (243,210,223,255) #F3D2DF srgba(243,210,223,1) 
     53: (243,221,230,255) #F3DDE6 srgba(243,221,230,1) 
     71: (244,233,237,255) #F4E9ED srgba(244,233,237,1) 
     8841: (245,245,244,255) #F5F5F4 srgba(245,245,244,1) 
    Rendering intent: Perceptual 
    Gamma: 0.45455 
    Chromaticity: 
    red primary: (0.64,0.33) 
    green primary: (0.3,0.6) 
    blue primary: (0.15,0.06) 
    white point: (0.3127,0.329) 
    Background color: white 
    Border color: srgba(223,223,223,1) 
    Matte color: grey74 
    Transparent color: none 
    Interlace: None 
    Intensity: Undefined 
    Compose: Over 
    Page geometry: 560x290+0+0 
    Dispose: Undefined 
    Iterations: 0 
    Compression: Zip 
    Orientation: Undefined 
    Properties: 
    date:create: 2015-03-19T10:05:06+00:00 
    date:modify: 2015-03-19T10:05:06+00:00 
    png:cHRM: chunk was found (see Chromaticity, above) 
    png:gAMA: gamma=0.45455 (See Gamma, above) 
    png:IHDR.bit-depth-orig: 8 
    png:IHDR.bit_depth: 8 
    png:IHDR.color-type-orig: 3 
    png:IHDR.color_type: 3 (Indexed) 
    png:IHDR.interlace_method: 0 (Not interlaced) 
    png:IHDR.width,height: 560, 290 
    png:PLTE.number_colors: 94 
    png:sRGB: intent=0 (Perceptual Intent) 
    png:tRNS: chunk was found 
    signature: 91476421108f784ce82d392aa2e58bc6c8c5991cf6466f5db98809cc16f0f2ca 
    Artifacts: 
    filename: gulp.png 
    verbose: true 
    Tainted: False 
    Filesize: 6.63KB 
    Number pixels: 162K 
    Pixels per second: 0B 
    User time: 0.000u 
    Elapsed time: 0:01.000 
    Version: ImageMagick 6.9.0-10 Q16 x86_64 2015-03-10 http://www.imagemagick.org 

tin.txt

Image: tin.png 
    Format: PNG (Portable Network Graphics) 
    Mime type: image/png 
    Class: DirectClass 
    Geometry: 560x290+0+0 
    Units: Undefined 
    Type: PaletteAlpha 
    Endianess: Undefined 
    Colorspace: sRGB 
    Depth: 8-bit 
    Channel depth: 
    red: 8-bit 
    green: 8-bit 
    blue: 8-bit 
    alpha: 8-bit 
    Channel statistics: 
    Pixels: 162400 
    Red: 
     min: 0 (0) 
     max: 245 (0.960784) 
     mean: 94.0738 (0.368917) 
     standard deviation: 113.927 (0.446772) 
     kurtosis: -1.82471 
     skewness: 0.407541 
     entropy: 0.400756 
    Green: 
     min: 0 (0) 
     max: 245 (0.960784) 
     mean: 101.679 (0.398739) 
     standard deviation: 81.0101 (0.317687) 
     kurtosis: -1.50733 
     skewness: 0.171586 
     entropy: 0.386438 
    Blue: 
     min: 0 (0) 
     max: 244 (0.956863) 
     mean: 145.019 (0.568702) 
     standard deviation: 89.1803 (0.349727) 
     kurtosis: -1.06731 
     skewness: -0.563292 
     entropy: 0.389441 
    Alpha: 
     min: 0 (0) 
     max: 255 (1) 
     mean: 197.073 (0.772837) 
     standard deviation: 106.446 (0.417434) 
     kurtosis: -0.298278 
     skewness: 1.30136 
     entropy: 0.179828 
    Image statistics: 
    Overall: 
     min: 0 (0) 
     max: 255 (1) 
     mean: 99.6745 (0.39088) 
     standard deviation: 98.5213 (0.386358) 
     kurtosis: -1.37999 
     skewness: 0.35773 
     entropy: 0.339116 
    Alpha: none #00000000 
    Colors: 53 
    Histogram: 
    36007: ( 0, 0, 0, 0) #00000000 none 
     664: ( 1, 40,117,255) #012875 srgba(1,40,117,1) 
     12: ( 1, 60,133,255) #013C85 srgba(1,60,133,1) 
     12: ( 1, 82,151,255) #015297 srgba(1,82,151,1) 
     17: ( 1,115,177,255) #0173B1 srgba(1,115,177,1) 
     29: ( 1,149,204,255) #0195CC srgba(1,149,204,1) 
    59276: ( 1,181,229,255) #01B5E5 srgba(1,181,229,1) 
     95: ( 1,181,229, 69) #01B5E545 srgba(1,181,229,0.270588) 
     93: ( 1,181,229, 19) #01B5E513 srgba(1,181,229,0.0745098) 
     91: ( 1,181,229,143) #01B5E58F srgba(1,181,229,0.560784) 
     83: ( 1,181,229, 40) #01B5E528 srgba(1,181,229,0.156863) 
     80: ( 1,181,229,224) #01B5E5E0 srgba(1,181,229,0.878431) 
     50: ( 1,181,229, 99) #01B5E563 srgba(1,181,229,0.388235) 
     46: ( 1,181,229,168) #01B5E5A8 srgba(1,181,229,0.658824) 
     39: ( 1,181,229,195) #01B5E5C3 srgba(1,181,229,0.764706) 
     30: ( 1,181,229,120) #01B5E578 srgba(1,181,229,0.470588) 
     64: (16,185,230,255) #10B9E6 srgba(16,185,230,1) 
     7: (36, 42,119,255) #242A77 srgba(36,42,119,1) 
     86: (40,191,232,255) #28BFE8 srgba(40,191,232,1) 
     281: (62,197,233,255) #3EC5E9 srgba(62,197,233,1) 
     11: (65, 44,120,255) #412C78 srgba(65,44,120,1) 
     68: (86,204,235,255) #56CCEB srgba(86,204,235,1) 
     24: (108,209,236,255) #6CD1EC srgba(108,209,236,1) 
     28: (118, 48,124,255) #76307C srgba(118,48,124,1) 
     267: (123,213,237,255) #7BD5ED srgba(123,213,237,1) 
     189: (133,121,180, 6) #8579B406 srgba(133,121,180,0.0235294) 
     55: (146,219,238,255) #92DBEE srgba(146,219,238,1) 
     22: (174, 52,127,255) #AE347F srgba(174,52,127,1) 
     218: (183,229,240,255) #B7E5F0 srgba(183,229,240,1) 
     84: (208,235,242,255) #D0EBF2 srgba(208,235,242,1) 
     49: (230,241,243,255) #E6F1F3 srgba(230,241,243,1) 
    53791: (232, 56,130,255) #E83882 srgba(232,56,130,1) 
     103: (232, 56,130,104) #E8388268 srgba(232,56,130,0.407843) 
     99: (232, 56,130, 18) #E8388212 srgba(232,56,130,0.0705882) 
     87: (232, 56,130, 60) #E838823C srgba(232,56,130,0.235294) 
     71: (232, 56,130,143) #E838828F srgba(232,56,130,0.560784) 
     69: (232, 56,130,224) #E83882E0 srgba(232,56,130,0.878431) 
     64: (232, 56,130,195) #E83882C3 srgba(232,56,130,0.764706) 
     52: (232, 56,130, 36) #E8388224 srgba(232,56,130,0.141176) 
     34: (232, 56,130, 80) #E8388250 srgba(232,56,130,0.313725) 
     33: (232, 56,130,168) #E83882A8 srgba(232,56,130,0.658824) 
     91: (234, 72,140,255) #EA488C srgba(234,72,140,1) 
     62: (234, 91,151,255) #EA5B97 srgba(234,91,151,1) 
     402: (235,103,159,255) #EB679F srgba(235,103,159,1) 
     51: (236,115,166,255) #EC73A6 srgba(236,115,166,1) 
     35: (237,127,173,255) #ED7FAD srgba(237,127,173,1) 
     77: (239,146,184,255) #EF92B8 srgba(239,146,184,1) 
     44: (239,162,194,255) #EFA2C2 srgba(239,162,194,1) 
     56: (240,174,201,255) #F0AEC9 srgba(240,174,201,1) 
     96: (242,194,213,255) #F2C2D5 srgba(242,194,213,1) 
     94: (243,217,227,255) #F3D9E3 srgba(243,217,227,1) 
     71: (244,233,237,255) #F4E9ED srgba(244,233,237,1) 
     8841: (245,245,244,255) #F5F5F4 srgba(245,245,244,1) 
    Rendering intent: Perceptual 
    Gamma: 0.454545 
    Chromaticity: 
    red primary: (0.64,0.33) 
    green primary: (0.3,0.6) 
    blue primary: (0.15,0.06) 
    white point: (0.3127,0.329) 
    Background color: white 
    Border color: srgba(223,223,223,1) 
    Matte color: grey74 
    Transparent color: none 
    Interlace: None 
    Intensity: Undefined 
    Compose: Over 
    Page geometry: 560x290+0+0 
    Dispose: Undefined 
    Iterations: 0 
    Compression: Zip 
    Orientation: Undefined 
    Properties: 
    date:create: 2015-03-19T10:04:55+00:00 
    date:modify: 2015-03-19T10:04:55+00:00 
    png:IHDR.bit-depth-orig: 8 
    png:IHDR.bit_depth: 8 
    png:IHDR.color-type-orig: 3 
    png:IHDR.color_type: 3 (Indexed) 
    png:IHDR.interlace_method: 0 (Not interlaced) 
    png:IHDR.width,height: 560, 290 
    png:PLTE.number_colors: 53 
    png:sRGB: intent=0 (Perceptual Intent) 
    png:tRNS: chunk was found 
    signature: f7e69fb1d6be1bde229a91d820f0f42330b923a37e28f0fccb181fdd6485c81c 
    Artifacts: 
    filename: tin.png 
    verbose: true 
    Tainted: False 
    Filesize: 5.59KB 
    Number pixels: 162K 
    Pixels per second: 0B 
    User time: 0.000u 
    Elapsed time: 0:01.000 
    Version: ImageMagick 6.9.0-10 Q16 x86_64 2015-03-10 http://www.imagemagick.org 

com.txt

Image: com.png 
    Format: PNG (Portable Network Graphics) 
    Mime type: image/png 
    Class: DirectClass 
    Geometry: 560x290+0+0 
    Units: Undefined 
    Type: PaletteAlpha 
    Endianess: Undefined 
    Colorspace: sRGB 
    Depth: 8-bit 
    Channel depth: 
    red: 8-bit 
    green: 8-bit 
    blue: 8-bit 
    alpha: 8-bit 
    Channel statistics: 
    Pixels: 162400 
    Red: 
     min: 1 (0.00392157) 
     max: 245 (0.960784) 
     mean: 110.909 (0.434937) 
     standard deviation: 104.021 (0.407927) 
     kurtosis: -1.74831 
     skewness: 0.209362 
     entropy: 0.377289 
    Green: 
     min: 40 (0.156863) 
     max: 245 (0.960784) 
     mean: 124.952 (0.490008) 
     standard deviation: 61.1171 (0.239675) 
     kurtosis: -1.32134 
     skewness: 0.22372 
     entropy: 0.367959 
    Blue: 
     min: 113 (0.443137) 
     max: 244 (0.956863) 
     mean: 170.07 (0.66694) 
     standard deviation: 53.7829 (0.210913) 
     kurtosis: -1.86532 
     skewness: 0.235003 
     entropy: 0.37823 
    Alpha: 
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Answer 2

Ich habe viel Zeit damit verbringen, die Implementierung und Kompressionsalgorithmen entwerfen, so lassen Sie mich eine teilweise Antwort geben - obwohl es wahrscheinlich nicht ist, was Sie wollen hören.

Wenn Sie lesen, wie die Komprimierung von PNG-Dateiformat funktioniert, z. here, finden Sie heraus, dass es Deflate-Komprimierung zusammen mit einem Prädiktor verwendet. Deflate Compression ist ein verlustfreier Komprimierungsalgorithmus - und obwohl Sie ihn mit einer besseren oder schlechteren Komprimierung implementieren können, würde ich davon ausgehen, dass die meisten Implementierungen in Bezug auf den Komprimierungsgrad ungefähr das gleiche Ergebnis liefern. Heutzutage beschäftigen sich die meisten Leute nicht mehr damit, Deflate zu implementieren, also wird die Komprimierung selbst wahrscheinlich nichts Gutes bringen.

Die Art, wie Werkzeuge wie die verknüpfte funktionieren, besteht darin, RGB-Farben auf indizierte Farben abzubilden. Wenn Sie nur eine begrenzte Anzahl von Farben (z. B. 256) haben, können Sie Ihr Bild in eine indizierte Darstellung konvertieren und erneut speichern. Weniger Farben bedeutet weniger Informationen zu kodieren, was bedeutet, dass Ihr Komprimierungsgrad steigt. Wenn Ihr Bild nur wenige Farben verwendet oder wenn Sie Informationen verlieren möchten, kann dies eine Option sein.

Wissen, was Sie suchen, ich denke, Sie können den gleichen Trick in fast jedes Bildpaket, das wie z. ImageMagick, Gimp. (In Gimp zB können Sie Bild -> Modus -> indiziert und speichern Sie erneut mit allen Optionen aus).