Change of contextPath, re-save theme
If you have changed the contextPath of your instance, you will need to re-save the theme in order for any pictures to show up correctly.
Additional information
When the theme is saved, the contextPath is saved at its current stage. Any updates to the contextPath will result in images and pictures not showing up correctly as these remain with the old contextPath. Saving the theme again will trigger the contextPath to be updated.