Yawcam -> Settings -> Offline image
Yawcam can upload or save an offline image when you are using ftp or file output.
Select the checkboxes for which output type the offline image shall be used for.
It is possible to upload/save an offline image on Yawcam's exit. (In other words if you exit Yawcam without to disable file or ftp first.) This will however delay the exit.
Change the image by clicking the "Change..." button and select an image.