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Medical image encryption based on DCT-DWT domain combining 2D-DataMatrix Barcode
(2016-02-04)
Nambutdee, Amarit
;
Airphaiboon, Surapan
In this paper, an application for medical image encryption and watermarking to store patient information is proposed. By using scrambling algorithm, the 1<sup>st</sup> view patient information is hidden and require unique patient password to access a real image. For watermarking scene, a Discrete Cosine Transform (DCT) and Discrete Wavelet Transform (DWT) are applied to non-overlapping block size 8x8 image pixels. Later, a DWT and DCT coefficient value are compared in each block for position identification of embed message in medical image. To improve high capacity and imperceptibility in watermarking step, a Two Dimension Barcode ECC200 standard is used to convert message before embed to cover image. Experimental results demonstrate that the proposed scheme achieves better performance of imperceptibility.
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Increase the hiding-bit capacity and strength for text watermarking with the line intersection on text image
(2012-10-08)
Yawai, Wiyada
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Hiransakolwong, Nualsawat
This research presents how to use the intersection position of horizontal line, virtually run across text character skeleton line on a text image under the cross ratio applying, to be the marking point of zero watermark; means watermarking without any actual watermark, which consequently increase the remarkable watermark hiding-bit capacity and robustness. One point of intersection across one text character skeleton line is one specific pixel which defined as one hiding-bit of zero watermark; just only marking its pattern, so that the more reference horizontal lines plotting, the more points of intersection would be got and increasing the hiding-bit capacity for watermarking which generally is the most limitation of other text watermarking methods. The high capacity for hiding bits means more chance to make many sets of redundant encrypted watermark data, in case some parts of text document image have been modified or tampered with. In addition, intersection points for virtually embedding watermarks still have a great strength for identifying the point of text which has been modified if all positions of intersection points are collected. Moreover, these intersection positions also has been applied with the cross ratio of four collinear points, to build up its robustness in order to survive from possibly attacking. The testing proved that this watermarking method can be effectively used to hide more redundant data, verify its integrity, be robust and easily apply it to multi-language text images such as English, Thai, Chinese and Arabic languages. © 2012 AICIT.
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Robust controller design for plant uncertainty
(2006-12-01)
Numsomran, A.
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Witheephanich, K.
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Tipsuwanporn, V.
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Klinsmitth, N.
This paper demonstrates how Robust Nominal Model Following Control (RNMFC) motivated by the adaptive model following concept is developed and proposed in this paper. The control structure of RNMFC is quite different from and much simpler than those of adaptive model following control schemes. RNMFC has three main features: the use of a nominal model of the plant as a reference model, the design of a model controller which fulfills the reference tracking requirement and the inclusion of a simple PID correction mechanism which copes with all dynamic deviations of the real plant from its nominal model. With its robust control structure, RNMFC separates the reference tracking and robustness fulfillment into two independent problems. The results illustrate the robustness of RNMFC that can be manipulated parametric uncertainty of motor servo system. © 2006 ICASE.
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Fast and robust control of systems with multiple flexible modes
(2005-10-01)
La-orpacharapan, Chanat
;
Pao, Lucy Y.
This paper derives shaped time-optimal servomechanism (STOS) closed-loop control laws using a phase-plane approach to address flexible structures having multiple flexible modes. The STOS control laws for systems having two and three flexible modes are detailed. The flexible modes are addressed by using multimode input shapers to shape the time-optimal control for the rigid body portion of the system. The altered rigid body phase-plane trajectories resulting from this shaping are solved and used to determine an STOS closed-loop controller. Both "convolution" and "simultaneous" method multimode input shapers are considered. We also improve the robustness to modeling errors of the STOS control. The more robust zero vibration and derivative (ZVD) shaper is used. The ZVD shaper consists of more impulses and has a longer time duration than the simpler zero vibration (ZV) shaper which leads to the more robust STOS (RSTOS) control derived from the ZVD shaper having more switches and longer time response than the STOS control derived from the ZV shaper. Simulation results show that using the ZVD shaper in deriving the RSTOS control improves the robustness to modeling errors in frequency and damping of the flexible mode. © 2005 IEEE.
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Digital watermarking methods of still images using the wavelet transform
(2002-01-01)
Thitimajshima, Punya
Digital watermarking methods of still images can be placed under two categories based on whether they cast the watermark in the spatial domain or in the transform domain. It was found that the transform domain watermarking schemes are typically much more robust to image manipulation as compared to the spatial domain schemes. In this paper, we will present a watermarking method based on the wavelet transform which does not require the original image for watermark detection. In our method, the original image is decomposed using multi-stage discrete wavelet transform. The watermark, generated by pseudo-random sequence, is added to all high-frequency coefficients that are above a given threshold. The watermarked image is finally obtained by using the inverse discrete wavelet transform. For watermark detection, we calculate the correlation between the wavelet coefficients of a possibly corrupted watermarked image and the watermark. By comparing the correlation with a predefined threshold, the embedded watermark can be detected. Experimental results are given to illustrate the robustness against smoothing, cropping, and JPEG compression.
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Copyright protection of images using human visual masking on DCT-based watermarking
(2002-01-01)
Rangsanseri, Y.
;
Thitimajshima, W.
In this paper a new watermarking algorithm for digital images operating in the frequency domain is presented: a sequence of pseudo-random real numbers is embedded in a selected set of DCT coefficients. After embedding, the watermark is adapted to the image to be signed by exploiting the masking characteristics of the Human Visual System (HVS) in order to achieve watermark invisibility without diminishing its robustness. Experimental results demonstrate that the watermark is robust to several signal processing techniques and geometric distortions.
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A robust variable step-size LMS-like algorithm for a second-order adaptive IIR notch filter for frequency detection
(2001-01-01)
Punchalard, R.
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Benjangkaprasert, C.
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Anantrasirichai, N.
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Janchitrapongvej, K.
The best adaptive algorithm requires fast convergence speed, low variance, unbias and low steady-state mean square error (MSE) in both low and high signal-to-noise ratio (SNR) situations. We have proposed a robust variable step-size LMS-like algorithm (VS-LMS-L) for a second-order adaptive IIR notch filter for frequency detection in radar, sonar and communication systems. This algorithm is compared with the conventional LMS-like algorithm called the plain gradient algorithm (PG). The time-varying step-size μ(n) is adjusted by using the square of the time-averaged estimate of autocorrelation of the present output signal y(n) and the past one y(n-1). This technique can reject the effect of the uncorrelated noise sequence on the step-size update, resulting in a small MSE due to the small final μ(n). Moreover, this algorithm can also improve the convergence speed by comparison with the PG at the same MSE value.

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