The disclosure describes a method of progressively decoding a digital
watermark on a distributed computing platform. A client device equipped
with a digital camera, such as a PDA or cell phone, captures a digital
image of a watermarked object, and pre-filters the image to isolate a
portion of the image data suspected of containing a digital watermark.
The pre-filter de-correlates a portion of the image data suspected of
containing a digital watermark from the remaining host image signal using
a predictive filter. The client then quantizes the filtered data and
progressively transmits the quantized data to a watermark decoder. The
progressive transmitter sends image data as necessary to achieve a valid
decoding operation. To reduce bandwidth requirements, the transmitter
starts with the most highly quantized version of the filtered image, and
sends lesser quantized versions until the watermark decoder completes a
successful decoding operation.