Encoding – what sort of images work best?
This section provides you with some simple watermarking guidelines. As you gain experience, you will undoubtedly refine these recommendations for your use.
- A busy image hides a watermark well, you will be able to easily apply a strong watermark signal without impacting your image quality.
- Areas of bright highlights or dark shadows do not accept watermarks well. In highlights, where color coverage approaches 0%, there are too few pixels to modify to add the signal. In shadows, where color coverage approaches 100%, the ability to modify pixels is essentially halved because of ink saturation. You may need to increase the strength setting using the slider to improve watermark detectability. You can also strengthen the watermark in highlights, but this usually negatively impacts visibility.
- For the same reason that highlights do not accept watermarks well, pure white areas — those with 0% color coverage — cannot be watermarked at all. If you must watermark a pure white area, consider adding a light color tint into larger white areas. It will need to be dark enough for your printer to reproduce for sufficient color coverage to embed a detectable watermark. Unfortunately, the watermark may become more visible with the added detectability.
- Identify areas for different watermark strengths by roughly the same criteria you use for unsharp masking in image editing software. For example, faces will probably require a lower watermarking strength; areas with lots of detail can take a watermark of higher strength.