Icons from embedded resources for ribbon bar

Hello everybody!
I am trying to use the c# API example code to access the ribbon bar:

...
RibbonButton button1Panel1 = new RibbonButton();
button1Panel1.ToolTip = "1";
button1Panel1.Text = "This is a managed ribbon button ...";
button1Panel1.CommandParameter = "command1";
button1Panel1.ExternalImage = true;
button1Panel1.Image = "icon1.bmp";
button1Panel1.Id = "1";
...

The code is working (icon is shown) if the file "icon1.bmp" is available under the directory "C:\Program Files\Bricsys\BricsCAD V20 de_DE\Support".
Now i would like to use an Icon out of the embedded resource file, which is compiled into the *.dll.
The common c# syntax should be like this:

...
button1Panel1.ExternalImage = true;
button1Panel1.Image = "CADPlugin.Resources.icon1.bmp"; // SOLUTION_NAME.Resources.FILENAME.FILETYPE
...

Using this Syntax the icon could not be found.

The API in AutoCAD is a little different: in AUTOCAD it is possible to set an icon directly by an image_object, not by its path: button1Panel1.Image = CADPlugin.Resource1.icon1; // this is the image reference, not a path

Is there any solution to use an icon from embedded resources?
please help, kind regards, waldo