Before adding a watermark

Keep in mind the following considerations before embedding a digital watermark in your image.

Color variation

The image must contain some degree of variation or randomness in color to embed the watermark effectively and imperceptibly. The image cannot consist mostly or entirely of a single flat color.

Pixel dimensions

The Digimarc technology requires a minimum number of pixels to work. Digimarc recommends the following minimum pixel dimensions for the image to be watermarked:

• 100 pixels by 100 pixels if you don't expect the image to be modified or compressed prior to its actual use.
• 256 pixels by 256 pixels if you expect the image to be cropped, rotated, compressed, or otherwise modified after watermarking.
• 750 pixels by 750 pixels if you expect the image to appear ultimately in printed form at 300 dpi or greater.

There is no upper limit on pixel dimensions for watermarking.

File compression

In general, a Digimarc watermark will survive lossy compression methods such as JPEG, though it is advisable to favor image quality over file size (a JPEG compression setting of 4 or higher works best). In addition, the higher the Watermark Durability setting you choose when embedding the watermark (see Using the Watermark Durability setting), the better the chances that the watermark will survive compression.

Workflow

Watermarking should be one of the very last tasks you perform, except for file compression. Use the following recommended workflow:

• Make all necessary modifications to your image until it has the desired final appearance (this includes resizing and color correction).
• Embed the watermark.
• If needed, compress the image by saving it in JPEG or GIF format.
• If the image is intended for printed output, perform the color separation.
• Read the watermark and use the signal strength meter to verify that the image contains a watermark of sufficient strength for your purposes.
• Publish the watermarked image.