```ruby
# encoding: utf-8

class AvatarUploader < CarrierWave::Uploader::Base

  include CarrierWave::MiniMagick

  # Override the directory where uploaded files will be stored.
  # This is a sensible default for uploaders that are meant to be mounted:
  def store_dir
    "uploads/#{mounted_as}/#{model.id}"
  end

  # Create different versions of your uploaded files:
  process :resize_to_fill => [200, 200]

  # Add a white list of extensions which are allowed to be uploaded.
  # For images you might use something like this:
  # def extension_white_list
  #   %w(jpg jpeg gif png)
  # end

  # Override the filename of the uploaded files:
  # Avoid using model.id or version_name here, see uploader/store.rb for details.
  # def filename
  #   "something.jpg" if original_filename
  # end

end
```

Tweak avatar uploader to avoid upscaling
user
```ruby
# encoding: utf-8

class AvatarUploader < CarrierWave::Uploader::Base

  include CarrierWave::MiniMagick

  # Override the directory where uploaded files will be stored.
  # This is a sensible default for uploaders that are meant to be mounted:
  def store_dir
    "uploads/#{mounted_as}/#{model.id}"
  end

  # Create different versions of your uploaded files:
  process :resize_to_limit => [250, 250]

  # Add a white list of extensions which are allowed to be uploaded.
  # For images you might use something like this:
  # def extension_white_list
  #   %w(jpg jpeg gif png)
  # end

  # Override the filename of the uploaded files:
  # Avoid using model.id or version_name here, see uploader/store.rb for details.
  # def filename
  #   "something.jpg" if original_filename
  # end

end
```
assistant