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Last active June 20, 2022 14:23
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Generate and optimise thumbnails using GraphicsMagick and pngquant
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thumbs.md

Generate and optimise thumbnails using GraphicsMagick and pngquant

Install

Install gm and pngquant.

apt-get install gm pngquant

Generate

Generate a thumbnail. You can replace -thumbnail with -resize for a clearer thumbnail that will result in a larger file size.

gm convert source_image.png -thumbnail 200x200 thumbnail_image.png

Generate a thumbnail while keeping horizonal aspect ratio.

gm convert source_image.png -thumbnail 200x thumbnail_image.png

Generate a thumbnail while keeping vertical aspect ratio.

gm convert source_image.png -thumbnail x200 thumbnail_image.png

Generate a thumbnail with a fix size and a fill-in background colour.

gm convert source_image.png -thumbnail 200x200 -background "#fff" -gravity center -extent 200x200 thumbnail_image.png

Optimise

Optimise thumbnail

pngquant --ext=.png -f thumbnail_image.png

Batch optimise thumbnails

find . -name "*.png" -print0 | xargs -0 sudo pngquant --ext=.png -f

GraphicsMagick. pngquant.

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