Introduction
Image Class 8 module will help site administrator to apply css class to 
image field through "Manage Display" of an entity type.


How it works
1. Go to "Manage Display" of an entity type
2. Select "Image class" format from Format column for image field 
3. Click on settings wheel of the image field
4. Enter css classes in Image Class textfield
5. Click "Update" button
6. Remember to click "Save" button after making necessary changes.