Intermediate Frequency Coefficients Research Articles

Analysis of DWT-DCT watermarking algorithm on digital medical imaging.

Over the past decade, the diagnostic information of the patients are digitally recorded and transferred. During the transmission of patients data, the security and authenticity of the information has to be ensured. Medical image watermarking technology has recently advanced because it can be used to conceal patient information while ensuring the authenticity. We propose a multiple watermarking method for securing clinical medical images. In this watermarking method, the quality feature property and private label property information are embedded as watermarks in the original image. Initially, medical images are divided into the region of interest (ROI) and non-interest region (NIR). Second, a two-level discrete wavelet transform (DWT) is applied to the ROI and the coefficients LL1 (LL2, LH2, HL2, HH2), LH1, HL1, and HH1 are generated. Watermarks are embedded using the DWT low-frequency sub-band (LL2) by quantizing the low-frequency coefficients. Next, the NIR is separated into non-overlapping blocks, and a discrete cosine transform (DCT) is applied for each block. The DCT coefficients of each block are sorted using the zigzag transform. For embedding, eight intermediate frequency coefficients are used. Finally, the feature information is embedded in the ROI, and the tag information is embedded in the NIR. The performance of the DWT-DCT watermarking method is calculated using the metrics of peak signal-to-noise ratio (PSNR), structural similarity index measure, and mean square error. The proposed method obtained the better PSNR value of 45.76dB. The proposed model works well for clinical medical images when compared with the existing techniques.

Adaptive Audio Watermarking Algorithm Based on Wavelet Transform

Aiming at the problem of small capacity and poor robustness of audio watermarking information, an adaptive digital audio blind watermarking algorithm based on wavelet transform is proposed. In this algorithm, each frame of the audio signal is converted into a discrete transform by using Haar wavelet, and the fine and approximate components are obtained, and the component masking threshold is calculated. Finally, the watermark embedding position is selected by the adaptive algorithm, quantized and modulated in the audio. The intermediate and low frequency coefficients of the signal. The simulation results show that the proposed algorithm has some resistance to common signal processing attacks and is robust to resampling and low-pass filtering attacks.

Imperceptible digital watermarking scheme in multiple transform domains

A novel imperceptible digital watermarking scheme in multiple transform domains is presented, where the cover image is dealt with by discrete wavelet transform (DWT), discrete cosine transform (DCT) and discrete fractional random transform (DFRNT), while the watermark image is scrambled by Arnold transform and logistic map. First the watermark is scrambled by the Arnold transform, then the row and the column of the resulting watermark are scrambled by the Logistic map, respectively. In addition, four sub-band images are generated from the host image by the two-dimensional discrete wavelet transform. The low-frequency sub-band images are divided into 8 × 8 small matrices, and a coefficient matrix is produced by performing the discrete cosine transform on each matrix. An intermediate matrix with the same size as the watermark image is constructed by the intermediate frequency coefficients. Then the discrete fractional random transformation is performed on the intermediate frequency coefficient matrix and the scrambled watermark is embedded into the discrete fractional random transformation domain. Compared with the previous schemes, the proposed digital watermarking scheme has stronger imperceptibility and robustness.

Video Watermarking Scheme Based on Candidates I-frames for Copyright Protection

<p>This paper focuses on moving picture expert group ( MPEG) based digital video watermarking scheme for copyright protection services. The present work implemented the video watermarking technique in which discrete cosine transform (DCT) intermediate frequency coefficients from instantaneous decoder refresh (IDR) frames are utilized. The subset of IDR frames as candidate frames are chosen to reduces the probability of temporal synchronization attacks to achieve better robustness and high visual perceptual quality. A secret key based cryptographic technique is used to enhance the security of embedded watermark. The proposed scheme embedded the watermark directly during the differential pulse code modulation (DPCM) process and extracting through decoding the entropy details. Three keys are required to extract the watermark whereas one of the key is used to stop the extraction process and the remaining two are used to display the watermark. The robustness is evaluated by testing spatial synchronization attacks, temporal synchronization attacks and re-encoding attacks. The present work calculates the simulation results that shows the watermarking scheme achieved high robustness against video processing attacks frequently occur in the real world and perceptibility also obtained without changing the motion vectors during the DPCM process of MPEG-2 encoding scheme.</p>

Digital Image Watermarking Algorithm Using the Intermediate Frequency

Digital image watermarking is one of the proposed solutions for copyright protection of multimedia data. This technique is better than Digital Signatures and other methods because it does not increase overhead. Watermarking adds the additional requirement of robustness. To improve the robustness of digital image watermarking method based on the image frequency, this paper adopts the intermediate frequency to embed the watermarking and proposes an digital image watermarking algorithm based on robust principal component analysis (RPCA) and discrete cosine transform (DCT). Firstly, the high frequency part and the low frequency part of the image are extracted by the RPCA algorithm. Because the high frequency part has complex statistical characteristics, this paper processes the high frequency part with 8×8 DCT method to obtain intermediate frequency coefficients and then the watermarking information is embedded into the obtained intermediate frequency coefficients. The experimental results show that the proposed algorithm leads to satisfactory robustness to the attacks of impulse noise and cropping.

A Blind Watermarking Algorithm Using DWT and DCT Techniques for Color Image

In this paper, a robust watermarking technique which combines features of Discrete Wavelet Transformation (DWT) and Discrete Cosine Transformation (DCT) is proposed. Firstly the original color image is converted from RGB space to Lab space. In this technique, DWT is used to decompose the luminance coefficients into various frequency and time scale. The block DCT is applied on DWT coefficients of middle frequency to provide high level of robustness. The encrypted watermark is embedded in it by comparison of the intermediate frequency coefficients. Then the color image is converted from Lab space to RGB space to get the watermarked image. Extracting the watermark does not need the original image and the original watermark, it is a blind watermarking method. Finally, the watermarked image is attacked. Peak signal-to-noise ratio (PSNR) value and the normalized correlation (NC) coefficient value are used to evaluate this technique. Simulation experiments show that the watermark is perceptually invisible, this method can achieve the highest possible robustness without losing the transparency.

Research and Implementation of an Integrity Video Watermarking Authentication Algorithm

The integrity video watermarking authentication algorithm is proposed based on DCT coefficients. Because of the characteristic of vulnerable to interference for high-frequency DCT coefficients, we use the relationship between the average energy of the high frequency coefficients and the energy of every the high frequency coefficients and Substitution cipher to beneficiate the Image Watermarking. The result is embedded in the intermediate frequency coefficients. Experimental results show that image of minor attacks will cause severe deformation so that it is difficult to extract the identifiable watermark. It can achieve the integrity authentication purposes.

A New Robust Zero-watermarking Algorithm for Medical Volume Data

Aiming at medical image information security problem, this paper proposes a new robust zero-watermarking algorithm for medical volume data based on three-dimensional discrete wavelet transform, three-dimensional Fourier transform and hermite chaotic neural network . Firstly, it employs a novel hermite chaotic neural network to generate the pseudo-random chaotic sequence for scrambling. Secondly, three dimensional medical image is transformed by three-dimensional discrete wavelet transform and three-dimensional discrete Fourier transform. Then, select the transformed low and intermediate frequency coefficients symbol as medical volume data characteristics to structure zero-watermarking. The algorithm integrates hermite chaotic neural network and zero-watermarking technology, which is not confined to artificially selected region of interest. The watermarking extraction does not need the original image. And its security depends on the chaotic sequence complexity and unpredictability, solving the watermark embedding, extraction safety and efficiency. The simulation results show that the algorithm is simple to implement, with good robustness, security and invisibility.

A Digital Watermark Algorithm for QR Code

Technology that combines a 2D BarCode with a digital watermark is a topic of great interest in current research related to the security field. This paper presents a new digital watermark method for the QR Code(Quick Response Code). An invisible watermark is embedded in the QR Code image using watermark technology, and while this is being done, the DCT intermediate frequency coefficients are compared. To prevent the overflow of the QR Code in the DCT domain of the image, QR image need fuzzy processing and be added noise to. In order to resist image distortion after print and scan operations, the watermark is embedded repeatedly. The watermark is extracted by using the two maximum membership degree of fuzzy pattern recognition, without the original image. Experimental results have demonstrated the feasibility of the algorithm.

基于对比度敏感度的无参考图像清晰度评价

A no reference image sharpness assessment method based on the property of Contrast Sensitivity Function(CSF) was proposed to realize the sharpness assessment of optical measurement equipment without reference television images.Firstly,a reference image for an original was constructed by a low-pass filter and both images were performed the Discrete Cosine Transform(DCT),and intermediate frequency coefficients and high frequency coefficients are divided into two parts respectively to be performed the Inverse DCT(IDCT) to obtain sub-images.Then,the Structural Similarity(SSIM) of corresponding sub-images was calculated.Finally,the image sharpness is obtained through the weighted sum of sub-image structural similarities.The experiment results show that the proposed method can obtain the Pearson Correlation Coefficient(CC) in 0.915 2,Spearman Rank Order Correlation Coefficient CC(SROCC) in 0.907 9 and out Rate(OR) in 0.034 5,which shows very high accuracy,monotonicity and consistency for the Gaussian blur image.The smallest defocus image can be quickly and accurately identified in the sequence defocus images and the effect is better than those of other four traditional focus evaluation functions.For different types of television blur images,the assessment results is more accord with human visual characteristics.It can be applied to optical measurement equipment television system and give accurate and reliable sharpness assessment of no reference television image.