Using ImageMagick to resize your Images [WebPerfTO]

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David Newton, St. Michael’s Hospital 1 1 Using ImageMagick to resize your Images Toronto Web Performance Group, 2015-03-17 Twitter: @newtron Github: @nwtn Email: david@davidnewton.ca Slides + image credits: https://github.com/nwtn/pres-imagemagick-webperfto

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3 Responsive images are a pain in the butt

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7 ImageMagick, y’all

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9 $ brew install imagemagick

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10 Condition File size: mean File size: % difference Photoshop CC, with optimization 260,304.70 KB ImageMagick `-resize` 337,665.98 KB 52.39%

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11 How does image resizing work?

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12 685,936 pixels 189,739 pixels

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13 …to 64 pixels? How do we get from 16 pixels…

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14 != resampling

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15 …to 64 pixels? How do we get from 16 pixels…

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16 …to 64 pixels? How do we get from 16 pixels… Background interpolation

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17 …to 64 pixels? How do we get from 16 pixels… Nearest-neighbour interpolation

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18 Nearest-neighbour interpolation

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19 Bicubic interpolation

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20 Nearest-neighbour vs. bicubic interpolation

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21 7 colours 1,146 colours

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More colours = More bytes* 23

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24 https://github.com/nwtn/image-resize-tests/

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25 How do we know which options are best?

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Quality objective: measured with DSSIM 26

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27 Control Test Difference

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Quality subjective: from me 29

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Test a variety of images 30

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31 The best* settings for ImageMagick

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32 mogrify -path OUTPUT_PATH -filter Triangle -define filter:support=2.0 -thumbnail OUTPUT_WIDTH -unsharp 0.25x0.08+8.3+0.045 -dither None - posterize 136 -quality 82 -define png:preserve-colormap=true - interlace none INPUT_PATH With optimization:

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33 https://imageoptim.com/

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34 mogrify -path OUTPUT_PATH -filter Triangle - define filter:support=2.0 -thumbnail OUTPUT_WIDTH -unsharp 0.25x0.25+8.00+0.065 - dither None -posterize 136 -background Black - alpha Background -quality 82 -define jpeg:fancy- upsampling=off -define png:compression-filter=5 -define png:compression-level=9 -define png:compression-strategy=1 -define png:exclude- chunk=all -interlace none -colorspace sRGB - strip INPUT_PATH Without optimization:

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35 mogrify -path OUTPUT_PATH -filter Triangle -define filter:support=2.0 -thumbnail OUTPUT_WIDTH -unsharp 0.25x0.08+8.3+0.045 -dither None - posterize 136 -quality 82 -define png:preserve-colormap=true - interlace none INPUT_PATH

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36 mogrify -path OUTPUT_PATH -filter Triangle -define filter:support=2.0 -thumbnail OUTPUT_WIDTH -unsharp 0.25x0.08+8.3+0.045 -dither None - posterize 136 -quality 82 -define png:preserve-colormap=true - interlace none INPUT_PATH

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37 Adaptive resize Distort resize Geometry Interpolative resize Liquid rescale Resize Sample Scale Thumbnail

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38 mogrify -path OUTPUT_PATH -filter Triangle -define filter:support=2.0 -thumbnail OUTPUT_WIDTH -unsharp 0.25x0.08+8.3+0.045 -dither None - posterize 136 -quality 82 -define png:preserve-colormap=true - interlace none INPUT_PATH

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39 (x1 ,y2 ) (x2 ,y2 ) (x1 ,y1 ) (x2 ,y1 ) (x,y) = + + +

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40 mogrify -path OUTPUT_PATH -filter Triangle -define filter:support=2.0 -thumbnail OUTPUT_WIDTH -unsharp 0.25x0.08+8.3+0.045 -dither None - posterize 136 -quality 82 -define png:preserve-colormap=true - interlace none INPUT_PATH

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42 mogrify -path OUTPUT_PATH -filter Triangle - define filter:support=2.0 -thumbnail OUTPUT_WIDTH -unsharp 0.25x0.25+8.00+0.065 - dither None -posterize 136 -background Black - alpha Background -quality 82 -define jpeg:fancy- upsampling=off -define png:compression-filter=5 -define png:compression-level=9 -define png:compression-strategy=1 -define png:exclude- chunk=all -interlace none -colorspace sRGB - strip INPUT_PATH

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43 Fancy

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43 Fancy

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44 mogrify -path OUTPUT_PATH -filter Triangle -define filter:support=2.0 -thumbnail OUTPUT_WIDTH -unsharp 0.25x0.08+8.3+0.045 -dither None - posterize 136 -quality 82 -define png:preserve-colormap=true - interlace none INPUT_PATH

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45 -unsharp 0.25x0.08+8.3+0.045 radius sigma gain threshold

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46 -unsharp 0.25x0.08+8.3+0.045 radius sigma gain threshold

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47 mogrify -path OUTPUT_PATH -filter Triangle -define filter:support=2.0 -thumbnail OUTPUT_WIDTH -unsharp 0.25x0.08+8.3+0.045 -dither None - posterize 136 -quality 82 -define png:preserve-colormap=true - interlace none INPUT_PATH

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52 mogrify -path OUTPUT_PATH -filter Triangle - define filter:support=2.0 -thumbnail OUTPUT_WIDTH -unsharp 0.25x0.25+8.00+0.065 - dither None -posterize 136 -background Black - alpha Background -quality 82 -define jpeg:fancy- upsampling=off -define png:compression-filter=5 -define png:compression-level=9 -define png:compression-strategy=1 -define png:exclude- chunk=all -interlace none -colorspace sRGB - strip INPUT_PATH

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More colours = More bytes* 54

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56 mogrify -path OUTPUT_PATH -filter Triangle -define filter:support=2.0 -thumbnail OUTPUT_WIDTH -unsharp 0.25x0.08+8.3+0.045 -dither None - posterize 136 -quality 82 -define png:preserve-colormap=true - interlace none INPUT_PATH

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57 quality 10 quality 40 quality 70 quality 100

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58 mogrify -path OUTPUT_PATH -filter Triangle - define filter:support=2.0 -thumbnail OUTPUT_WIDTH -unsharp 0.25x0.25+8.00+0.065 - dither None -posterize 136 -background Black - alpha Background -quality 82 -define jpeg:fancy- upsampling=off -define png:compression-filter=5 -define png:compression-level=9 -define png:compression-strategy=1 -define png:exclude- chunk=all -interlace none -colorspace sRGB - strip INPUT_PATH

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59 mogrify -path OUTPUT_PATH -filter Triangle -define filter:support=2.0 -thumbnail OUTPUT_WIDTH -unsharp 0.25x0.08+8.3+0.045 -dither None - posterize 136 -quality 82 -define png:preserve-colormap=true - interlace none INPUT_PATH

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60 mogrify -path OUTPUT_PATH -filter Triangle - define filter:support=2.0 -thumbnail OUTPUT_WIDTH -unsharp 0.25x0.25+8.00+0.065 - dither None -posterize 136 -background Black - alpha Background -quality 82 -define jpeg:fancy- upsampling=off -define png:compression-filter=5 -define png:compression-level=9 -define png:compression-strategy=1 -define png:exclude- chunk=all -interlace none -colorspace sRGB - strip INPUT_PATH

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62 mogrify -path OUTPUT_PATH -filter Triangle -define filter:support=2.0 -thumbnail OUTPUT_WIDTH -unsharp 0.25x0.08+8.3+0.045 -dither None - posterize 136 -quality 82 -define png:preserve-colormap=true - interlace none INPUT_PATH

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65 Progressive JPEGs Good? Evil?

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66 mogrify -path OUTPUT_PATH -filter Triangle - define filter:support=2.0 -thumbnail OUTPUT_WIDTH -unsharp 0.25x0.25+8.00+0.065 - dither None -posterize 136 -background Black - alpha Background -quality 82 -define jpeg:fancy- upsampling=off -define png:compression-filter=5 -define png:compression-level=9 -define png:compression-strategy=1 -define png:exclude- chunk=all -interlace none -colorspace sRGB - strip INPUT_PATH

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68 mogrify -path OUTPUT_PATH -filter Triangle -define filter:support=2.0 -thumbnail OUTPUT_WIDTH -unsharp 0.25x0.08+8.3+0.045 -dither None - posterize 136 -quality 82 -define png:preserve-colormap=true - interlace none INPUT_PATH With optimization:

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69 mogrify -path OUTPUT_PATH -filter Triangle - define filter:support=2.0 -thumbnail OUTPUT_WIDTH -unsharp 0.25x0.25+8.00+0.065 - dither None -posterize 136 -background Black - alpha Background -quality 82 -define jpeg:fancy- upsampling=off -define png:compression-filter=5 -define png:compression-level=9 -define png:compression-strategy=1 -define png:exclude- chunk=all -interlace none -colorspace sRGB - strip INPUT_PATH Without optimization:

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70 Why even bother?

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71 Condition File size: mean File size: % difference My settings, optimization 221,583.36 KB My settings, no optimization 260,250.18 KB 17.45% Photoshop CC, optimization 260,304.70 KB 17.48% CodeIgniter / ExpressionEngine 276,112.95 KB 24.61% Photoshop CC, no optimization 299,709.70 KB 35.26% TYPO3.CMS 321,602.95 KB 45.14% WordPress 337,665.98 KB 52.39% Drupal 344,246.42 KB 55.36% Perch 348,735.82 KB 57.38% Craft CMS 372,055.63 KB 67.91% grunt-responsive-images 426,623.28 KB 92.36%

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72 OK… but it’s still a pain in the butt

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73 https://www.npmjs.com/package/grunt-respimg

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74 Resizing with smart defaults SVG to PNG rasterization Optimization

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75 npm install grunt-respimg --save-dev

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David Newton, St. Michael’s Hospital 78 1 Using ImageMagick to resize your Images Toronto Web Performance Group, 2015-03-17 Twitter: @newtron Github: @nwtn Email: david@davidnewton.ca Slides + image credits: https://github.com/nwtn/pres-imagemagick-webperfto