Cryptography Reference
In-Depth Information
Fig. 10.11.
An example of watermark generated in a special design, and the right
one is an expanded area in the left image.
(2) Decoding in a server.
As shown in Fig. 10.1, the method of decoding in a mobile phone is the way
in which the watermark is decoded from a captured image by a calculation
in a mobile phone. The merit of this detection method is that the process
of decoding will not be affected by the mobile phone communication state.
The drawback of this method is that it consumes too much time for decoding
calculation, because of the limited computing capability of current mobile
phones.
As shown in Fig. 10.2, the method of decoding in a server is a way in
which the watermark is decoded from a captured image. This is done by
sending captured image to the server and by the calculation in that server.
The merit of this method is that watermark can be decoded by using a highly
effective scheme for the calculation. The drawback of this method is that
the transmission of a picture from mobile phone to a server may be greatly
changed. It may also take too much time when the communication of mobile
phones is congested.
10.6 Image Recognition Methods
The fourth kind of method used for the applications of print-to-web linking
technology using a mobile phone camera is the method using Image Recogni-
tion Techniques. Contrary to the watermarking methods, the major merits of
image recognition techniques are their high rate of image recognition and high
image quality. The reasons are that the pictures captured with mobile phone
cameras are retrieved by image features without embedding and further for
the image. A captured image can be easily recognized by the use of Image
Recognition Techniques.
