Rails 3.2 - how to write an image path in a config/initializer script ?

[Erwin]

In my config/initializers/payday.rb  , I need to write an image path to an asset image ...

Currently it's written like that :

Payday::Config.default.invoice_logo = "#{Rails.root}/public/images/store/logo.png"

how can I set the path, as asset_path cannot be used yet during initialization ?

if not possible I guess I should have a copy of the image in the public folder ?

thanks for feedback