Abstract
In this paper, we describe a new aspect to evaluating the robustness
of the optical watermarking technique, which is a unique technology that can
add watermarked information to object image data taken with digital cameras
without any specific extra hardware architecture. However, since this technology
uses light with embedded watermarked information, which is irradiated onto
object images, the condition of taking a picture with digital cameras may
affect the accuracy with which embedded watermarked data can be detected.
Images taken with digital cameras are usually defocused, which occurs under
non-optimal conditions. We evaluated the defocusing in images against the
accuracy with which optical watermarking could be detected. Defocusing in
images can be expressed with convolution with a line-spread function (LSF).
We used the value of full-width at half-maximum (FWHM) of a Gaussian function
as the degree to which images were defocused, which could approximate LSF.
We carried out experiments where the accuracies of detection were evaluated
as we varied the degree to which images were defocused. The results from the
experiments revealed that optical watermarking technology was extremely robust
against defocusing in images.
© 2013 IEEE
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