Thank you for your interest in RadImageEditor for WPF!
The scenario you explained should be possible using RadImageEditor and other controls from the suite. Please note that a drawing tool is currently not available. It is possible to implement a custom tool in the manner demonstrated in the Custom Tool demo
for RadImageEditor (you can also see it here
as the code-base is the same), however the task is not trivial.
Once you obtain the encoded representation of the image from a database, you can use format providers
to decode it. After executing the wanted changes you can preserve the modified image to the same or a separate data entry again using a format provider. Note that the undo/redo history will only work while the image is shown in the image editor. In case you change the image in the editor, it will no longer be possible to revert the made modifications.
In addition, I will suggest you to review the RadImageEditor
from our ASP.NET AJAX suite. In order to load images from a database in it you will also need to implement a custom content provider
but it provides a built-in drawing functionality. You might find useful information on the subject in this blog post
and this demo
I hope this information was helpful for you.