If you want to save the image in local table, you might want to convert the image file to base64 and then store it in some property. Pega does the same while storing attachment in one case. You can refer that.
I created one field group list property as item details, in that item image and some other fields are there. So while the case is running the entered data should store in my local data store. How to do that, because it is a field group list I do not know what to do and it also contains images in it.