DerivedImages

ActiveStorage's variant functionality is awesome, so why not have it for images in the Rails asset pipeline too?

Use DerivedImages to programmatically create image assets by applying transformations to other assets. Resize images, lower quality to save bytes, rotate, crop, convert between formats, and anything else that the image_processing gem supports.

1. Run ./bin/bundle add derived_images
2. Run ./bin/rails derived_images:install
3. Install Vips or ImageMagick (if not already installed for ActiveStorage/ImageProcessing)
   • MacOS: brew install vips or brew install imagemagick
   • Debian/Ubuntu: apt install libvips42 or apt install imagemagick

After installing, specify images to create in the config file at config/derived_images.rb.

derive 'my_derived_image.webp', from: 'my_source_image.jpg'
resize 'tiny.png', from: 'original.png', width: 400, height: 300
derive 'fully_custom.jpg', from: 'original.jpg' do |pipeline|
  pipeline.saver(quality: 50).resize_to_fill(80, 80).rotate(180)
end

DerivedImages watches this file and the source images, compiling new assets into app/assets/builds where the asset pipeline can pick them up with the normal asset helpers.

<%= image_tag('tiny.png') %>

The gem is available as open source under the terms of the MIT License.