Question

I’m using RMagick and want my images to be resized to a fixed width of 100px, and scale the height proportionally. For example, if a user were to upload a 300x900px, I would like it to be scaled to 100x300px.

Answer 1

Just put this in your uploader file:

class ImageUploader < CarrierWave::Uploader::Base

  version :resized do
    # returns an image with a maximum width of 100px 
    # while maintaining the aspect ratio
    # 10000 is used to tell CW that the height is free 
    # and so that it will hit the 100 px width first
    process :resize_to_fit => [100, 10000]
  end

end

Documentation and example here: http://www.imagemagick.org/RMagick/doc/image3.html#resize_to_fit

Keep in mind, resize_to_fit will scale up images if they are smaller than 100px. If you don’t want it to do that, then replace that with resize_to_limit.