A Generation Method of Amplitude-Only Images with Low Intensity Ranges

Wannida SAE-TANG  Masaaki FUJIYOSHI  Hitoshi KIYA  

Publication
IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E96-A   No.6   pp.1323-1330
Publication Date: 2013/06/01
Online ISSN: 1745-1337
DOI: 10.1587/transfun.E96.A.1323
Print ISSN: 0916-8508
Type of Manuscript: Special Section PAPER (Special Section on Circuit, System, and Computer Technologies)
Category: 
Keyword: 
random sign,  intensity range reduction,  quantization,  amplitude-only image,  copyright protection,  

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Summary: 
In this paper, 1) it is shown that amplitude-only images (AOIs) have quite wide intensity ranges (IRs), and 2) an IR reduction method for AOIs is proposed. An AOI is the inversely transformed amplitude spectra of an image, and it is used in the privacy- and copyright-protected image trading system because of its invisibility. Since an AOI is the coherent summation of cosine waves with the same phase, the IR of the AOI is too large to be stored and/or transmitted. In the proposed method, random signs are applied to discrete Fourier transformed amplitude coefficients to obtained AOIs with significantly lower IRs without distortion while keeping the invisibility of images. With reasonable processing time, high correct watermark extracting rates, inversely quantized AOIs with low mean squared errors, and reconstructed images with high peak signal-to-noise ratios are obtained by a linear quantizer in the proposed method.