To specify you want to search for large images you can do one of two things:

1. Search from the “Google” source and in the advanced search settings (drop down arrow next to the search button) set image size to Extra Large.

2. You can search from Flickr, SmugMug and DeviantArt together (by configuration the “All Sources” advanced search settings). All three usually (~90% of results) have large sizes available for results – the Large and Original sizes. Select different sizes in the Preview window on the bottom left corner.

We may implement more ways to specify resolution for searches in future versions.