In Drupal 7, What is a good approach to copy the image from one imagefield to another imagefield? I'd like to allow the user to upload an image once, and have it apply to 3 other image fields on the same page without requiring the user to submit the form. Afterwards I intend to apply different croppings to each image but that may not be related to this question.

Is there an existing module or solution to this? If not, what is a good place to inject this behavior client side?
You should only use one image field, and then setup 3 image styles at:


  admin/config/media/image-styles


For each image style you can define a number of different actions, like cropping. When displaying the image you can use theme_image_style()

This is a part of Drupal core and can be extended by e.g. ImageCache Actions.