Browsing by Author "Chao, Kun-Yuan"

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SECRET IMAGE SHARING: A BOOLEAN-OPERATIONS-BASED APPROACH COMBINING BENEFITS OF POLYNOMIAL-BASED AND FAST APPROACHES
(2009-03-01)
Chao, Kun-Yuan
;
Lin, Ja-Chen
;
資訊工程學系
;
Department of Computer Science
In secret image sharing, a polynomial interpolation technique heavy experiences a computation load when the secret image is retrieved later. To the contrary, fast approaches often need larger storage space due to pixel expansion property. This paper proposes a missing-allowable (k, n) scheme which is fast and with a reasonable pixel expansion rate (per). The scheme generates n extremely-noisy shadow images for the given secret color image A, and any k out of these n shadows can recover A loss-freely. In average, to decode a color pixel of A, the retrieval uses only three exclusion-OR operations among 24-bit numbers. Hence, the new method has very fast decoding speed, and its pixel expansion rate is always acceptable (0 < per < 2).
Sharing of multiple images: economically sized and fast-decoding approach based on modulus and Boolean operations
(2010-04-01)
Chao, Kun-Yuan
;
Lin, Ja-Chen
;
資訊工程學系
;
Department of Computer Science
Secret image sharing is a popular technology to secure digital images in storage and transmission. Traditionally, the technology transforms one secret image into several images called shadows or shares. Later, when the number of collected shadows reaches a specified threshold value, the decomposed image can be reconstructed. We propose a new sharing approach to transform n secret images into n shadows. Later, after gathering all the n shadows, all the n secret images can be retrieved error-free. No information in any secret image is revealed if one shadow is absent. The total size of n generated shadows is identical to the total size of n input secret images; hence, this approach does not waste storage space. Each pixel in each secret image is reconstructed using only one Boolean, one modulus, and two mathematical operations, so it is also a fast approach for reconstructing many secret images. Comparisons are included. (C) 2010 Society of Photo-Optical Instrumentation Engineers. [DOI: 10.1117/1.3407067]
User-friendly sharing of images: progressive approach based on modulus operations
(2009-07-01)
Chao, Kun-Yuan
;
Lin, Ja-Chen
;
資訊工程學系
;
Department of Computer Science
Image sharing is a popular technology to secure important images against damage. The technology decomposes and transforms an important image to produce several other images called shadows or shares. To decode, the shared important image can be reconstructed by combining the collected shadows, as long as the number of collected shadows reaches a specified threshold value. A few sharing methods produce user-friendly (i.e., visually recognizable) shadows-in other words, each shadow looks like a replica of reduced visual quality of a given image, rather than completely meaningless random noise. This facilitates visual management of shadows. (For example, if there are 100 important images and each creates 2 to 17 shadows of its own, then it is easy to visually recognize that a stored shadow is from, say, a House image, rather than from the other 99 images.) In addition to visually recognizable shadows, progressive decoding is also a convenient feature: it provides the decoding meeting a convenient manner to view a moderately sensitive image. Recently, Fang combined both conveniences of visually recognizable shadows and progressive decoding [ W. P. Fang, Pattern Recogn., 41, 1410-1414 (2008)]. But that method was memory expensive because its shadows were too big. In order to save memory space, we propose a novel method based on modulus operations. It still keeps both conveniences, but shadows are two to four times smaller than Fang's, and the visual quality of each shadow can be controlled by using a simple expression. (C) 2009 SPIE and IS&T. [DOI: 10.1117/1.3206950]