This image is a Custom Module in Joomla Module manager, like so: www.screencast.com/t/Fk4Jhd267D7f where you can change the image. Since this section is on 2 pages Home & About, therefore there are 2 custom image modules one for Home & other for About pages respectively with the same name though.
Let us know if you managed to find this one or not.
If you like our support and products, tweet us at joomdev and let the world know about it.
JoomDev is not affiliated with or endorsed by Open Source Matters or the Joomla! Project. The Joomla! logo is used under a limited license granted by Open Source Matters the trademark holder in the United States and other countries.