digiKam supports watermarking, this feature is hidden so well that you might not even realize that it’s there. This is because the watermarking function in digiKam is tucked under the Batch Queue Manager tool which you can use to watermark multiple photos in one go. Here is how this works in practice. Choose Tools | Batch Queue Manager (or press the B key) to open the Batch Queue Manager tool. Drag the photos you want to watermark from a digiKam album onto the Queues pane to add them to the current queue. Click on the Base Tools tab in the Batch Tools Available pane and double-click on the Add Watermark tool to add it to the Assigned Tools pane.