GIMP is an acronym for GNU Image Manipulation Program. It is a freely distributed program for such tasks as photo retouching, image composition and image authoring. It can slao help you to add a hidden watermark, so that you could protect your image right. Here is the instruction to tell you how to do it.
1. Download and install GIMP from here:
2. Start the program. Create a new layer with your own words or image, and this would be the water mark showed on the picture.
3. Lower the opacity of this layer so that it won’t cover your image. But make sure the opacity is not zero.
4. Merge both your layers and save this image under a new name.
5. Ensure that you have incorporated the integrity of ownership or proof of ownership before uploading.
6. Once you need to revel your watermark as evidence, you could do this: change the layer-mode to “Grain extract” and merge both layers. Go to filters-enhance-unsharp mask and change the amount to 10.0.