A helpful resource for gathering images of different emotions is ImageSource.com, a stock photography database. To find a variety of images that capture expressions of emotion or represent a particular emotion, navigate to ImageSource.com, scroll down to the Popular Categories menu, and select the Feelings and Emotions link.
Searching "Emotions Faces" on ShutterStock.com provides many composite photos in which a male, female or cartoon face expresses a different emotion in each frame. This allows for easy comparisons of facial expression. Similar results are available by navigating to CanStockPhoto.com and entering "Emotions" as the keyword in the Images search box. DreamsTime.com is another stock photography website that contains quality images of people displaying various emotions. Many stock photos are available to download at no charge.