So, ich hab was gefunden was zu funktionieren scheint:
Delphi-Quellcode:
procedure Tf_main.Speichern1Click(Sender: TObject);
var pathandname:string;
ob:TBitmap32;
i:integer;
begin
pathandname:='test.png';
ob:=TBitmap32.Create;
ob.Width:=openimages.ia[aktive].image.Width;
ob.Height:=openimages.ia[aktive].image.Height;
for i:=0 to openimages.ia[aktive].image.Layers.Count-1 do
ob.Draw(0,0,TBitmapLayer(openimages.ia[aktive].image.Layers.Items[i]).Bitmap);
SavePicToFile(pathandname,ob);
ob.Free;
end;