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Is your feature request related to a problem? Please describe.
Not a problem with gradio, although perhaps related to a problem with society and sharing online images. Watermarking helps to:

• Mark content so that people know how synthetic it is / whether it's synthetic at all: Content can be marked as fully synthetic (AI-generated), such as DeepFakes; non-synthetic (such as images from a camera); and anywhere in between.
• Mark ownership (of all kinds of content).
• Mark content with a resource to get more information (such as with a watermark QR code).

Describe the solution you'd like
watermarked_image = gr.Image(image, watermark=watermark_file)

Additional context
Currently, gr.Video() can take a watermark argument, with a path to a watermark image file, in order to watermark the video.
I propose making a parallel functionality in gr.Image().