This paper has discussed about tracing of digital images on
World Wide Web, and also proposes an architecture design of
watermark tracing system. This paper proposes that Quick
Response Code is embedded with an invisible metadata by
using DCT for copyright digital media. The encoding process
used the DCT to allow QR Code to be broken up into DC
frequency bands using 8x8 block DCT based method. The QR
code extraction system determines a metadata in the QR Code
by reverse the embedded process from the invisible QR code.
This digital image with metadata preserves an information
hiding text in the QR Code.
We use the histogram of DC image parameter as indexing
key in the target database, which will be used to retrieve the
original image from the source database. DC image is obtained
by taking all DC value of each 8x8 image block after DCT
transform, which also serve as thumbnail version of the original.
Besides to get the DC image, the operation of 8x8 DCT
transform is also used to extract the watermark in the next data
hiding process module, which increases the efficiency of the
overall system. It could be employed in practice application to
trace the copyright digital data across the internet.