Layering overlapping images - watermark over all, including images

Greetings,

I would like to place a watermark over the entire page.
Using the draft mode and watermark image params, the image is place on the
page, however it seems to be on the "bottom."

How might one place the watermark over the entire page so that it would
mark over non-transparent images?

Presently the watermark is clipped at the edges of images, which are not
transparent.
Hence my assumption that the watermark image is on the "bottom" of stacking
layers.

Best regards,

..Otto