How to Add a Graphic Watermark to an Image in GIMP
To overlay a semi-transparent watermark on an image in GIMP:
Open the image in GIMP and go to File > Open as Layers. Choose the graphic you want to use as a watermark, then select Open. Select Convert if prompted to convert the image to RBG. Select the Move tool, then position the graphic in the desired location. Go to Windows > Dockable Dialogs > Layers to open the Layers palette (if it isn’t visible). Select the layer with your watermark graphic, then drag the Opacity slider to the left to make the image semi-transparent. Depending on the photo being watermarked, change the color of the graphic. For example, to apply a black graphic as a watermark on a dark image, change the graphic to white to make it more obvious. In the Tools palette, select Foreground Color to open the Change Foreground Color dialog box, choose a color, then select OK. Go to Edit > Fill With FG Color to change the color of the graphic. Go to the Layers palette, select the graphic layer, then select the paintbrush icon. Click the empty space under the paintbrush to ensure that transparent pixels remain transparent if you edit the layer.
Adding graphic watermarks to digital images doesn’t guarantee that they won’t be stolen, but the time required to remove a semi-transparent watermark discourages most would-be image thieves. It’s possible to make a watermark in GIMP without the need for any extra plugins or extensions.
