CarrierWave Watermarker

Watermarker provides a simple processor for placing watermark on images.

class ImageUploader < CarrierWave::Uploader::Base
  include CarrierWave::Watermarker

  process watermark: "#{Rails.root}/app/assets/images/watermark.png"

  version :thumbnail do
    process watermark: ["#{Rails.root}/app/assets/images/watermark.png", 'Center']
  end
end

Watermark process accepts one or two parameters. Second optional parameter it's a place where you want to place watermark. You can choose one of these places: None, Center, East, Forget, NorthEast, North, NorthWest, SouthEast, South, SouthWest, West, Static

Add this line to your application's Gemfile:

gem 'carrierwave_watermarker'

And then execute:

$ bundle

CarrierWave Watermarker uses MiniMagick

On OS X:

$ brew install imagemagick