An implied usage license comes into play in the absence of a written image license. The scope of the implied usage will be limited to what the original intent of the images were for. So in the context of a test shoot or TF shoot where a photographer refuses to give images to the model, the model can take those images from the photographer's web site and use them in her portfolio site in accordance with the intent of the collaboration. The use just has to be consistent with the intended purpose of the shoot. So lets say a photographer is contacted by an agency to test a model for her book. The photographer accepts and based on past arrangements and standard agency practices, the images are used in the model's book without a credit to the photographer. The photographers didn't give the model a written license but did give her 9x12 prints. The photographer can't go back and claim she didn't have a license to use the images in her book.