This paper reports an efficient Discrete Cosine Transform (DCT) processing method for images using a massive-parallel memory-embedded SIMD matrix processor. The matrix-processing engine has 2,048 2-bit processing elements, which are connected by a flexible switching network, and supports 2-bit 2,048-way bit-serial and word-parallel operations with a single command. For compatibility with this matrix-processing architecture, the conventional DCT algorithm has been improved in arithmetic order and the vertical/horizontal-space 1 Dimensional (1D)-DCT processing has been further developed. Evaluation results of the matrix-engine-based DCT processing show that the necessary clock cycles per image block can be reduced by 87% in comprison to a conventional DSP architecture. The determined performances in MOPS and MOPS/mm2 are factors 8 and 5.6 better than with a conventional DSP, respectively.

This paper presents a novel technique to compensate intermodulation distortion of a self-heterodyne direct conversion OFDM system in multipath propagation environments. A self-heterodyne direct conversion system has an advantage that simple receivers can be built that are completely immune to any phase noise or frequency offset. This system, however, has a disadvantage that the nonlinear square-law detector at the receiver of the self-heterodyne direct conversion system gives rise to second order intermodulation distortion. In this study, channel estimation is performed using a training sequence and then the predistortion coefficients with regard to estimated channel parameters are derived to compensate the receiver nonlinearity. Transmit power distribution is employed to overcome multipath fading channels as well. Computer simulation demonstrates that the proposed approach improves the BER performance of the self-heterodyne direct conversion OFDM system in a multipath fading channel. This scheme gives advantage to multi-carrier systems that are much more sensitive to frequency and phase error than single-carrier systems.

In this letter, we propose a novel subsampling based image watermark sequentially embedding scheme to reduce the risk of common permutation attack. The image is still perceptual after watermarking, and experimental results also show its effectiveness and robustness.

In this paper, we proposed an efficient coding method for digital hologram (fringe pattern) acquired with a CCD camera or by computer generation using multi-view prediction and MPEG video compression standard techniques. It processes each R, G, or B color component separately. The basic processing unit is a partial image segmented as the size of MN. Each partial image retains the information of the whole object. This method generates an assembled image for a column of the segmented and frequency-transformed partial images, which is the basis of the coding process. That is, a motion estimation and compensation technique of MPEG is applied between the reconstructed images from the assembled images with the disparities found during generation of assembled image and the original partial images. Therefore the compressed results are the disparity of each partial image to form the assembled image for the corresponding column, assembled image, and the motion vectors and the compensated image for each partial image. The experimental results with the implemented algorithm showed that the proposed method has NC (Normalized Correlation) values about 4% higher than the previous method at the same compression ratios, which convinced us that ours has better compression efficiency. Consequently, the proposed method is expected to be used effectively in the application areas to transmit or store in digital format the digital hologram data.

Color correction needs to be performed to improve the quality of image/video production. The typical methods realize the color correction mainly in the spatial domain of RGB color space. In this paper, a linear color correction method in JPEG/MPEG-2 compressed domain is proposed. The correction is realized in the DCT domain of YUV color space without full-frame decompression. Experimental results show that the visual quality of the corrected images/videos in the compressed domain is identical to the quality of the images/videos corrected in the uncompressed domain.

The convergence speed of the conventional adaptive LMS algorithms for time delay estimation (TDE) is highly dependent on the spectral distribution of the desired random source signals of interest, thus the performance of TDE might be degraded, dramatically. To solve this problem, in this letter, a DCT-transform domain constrained adaptive normalized-LMS filtering scheme, referred to as the adaptive constrained DCT-LMS algorithm, is devised for TDE. Computer simulation results verify that the proposed scheme can be used to achieve desired performance, for input random signals with different spectral distributions; it outperforms the unconstrained DCT-LMS and time-domain constrained adaptive LMS algorithms.

We propose a novel strategy to obtain a high spatio-temporal resolution video. To this end, we introduce a dual sensor camera that can capture two video sequences with the same field of view simultaneously. These sequences record high resolution with low frame rate and low resolution with high frame rate. This paper presents an algorithm to synthesize a high spatio-temporal resolution video from these two video sequences by using motion compensation and spectral fusion. We confirm that the proposed method improves the resolution and frame rate of the synthesized video.

We propose a novel blind watermarking algorithm, called XFuseMark, which can hide a small, visually meaningful, grayscale logo in a host image instead of using a random-noise-like sequence based on the multiresolution fusion principles, and extract a recognizable version of the embedded logo even without reference to the original host data at the receiving end. XFuseMark is not only secure, i.e., only authorized users holding a private key are able to conduct the logo extraction operation, but also robust against noise addition and image compression. Experiments verify the practical performance of XFuseMark.

When the frame size is downscaled for video transcoding, the new motion vector (MV) must be computed. This paper presents an algorithm to utilize the activity measurement by DC value and the number of non-zero quantized DCT coefficients in the residual macroblock to compose the motion vector. It can reduce the complexity for motion estimation and improve the performance of the spatial domain video transcoder.

In recent years, the demand for multimedia mobile battery-operated devices has created a need for low power implementation of video compression. Many compression standards require the discrete cosine transform (DCT) function to perform image/video compression. For this reason, low power DCT design has become more and more important in today's image/video processing. This paper presents a new power-efficient Hybrid DCT architecture which combines Loeffler DCT and binDCT in terms of special property on luminance and chrominance difference. We use Synopsys PrimePower to estimate the power consumption in a TSMC 0.25-µm technology. Besides, we also adopt a novel quality assessment method based on structural distortion measurement to measure the quality instead of peak signal to noise rations (PSNR) and mean squared error (MSE). It is concluded that our Hybrid DCT offers similar quality performance to the Loeffler, and leads to 25% power consumption and 27% chip area savings.

This letter proposes to employ the Discrete Cosine Transform (DCT) interpolation-based channel estimation (DCTI-CE) method for practical MIMO-OFDM (Multiple Input Multiple Output--Orthogonal Frequency Division Multiplexing) system so as to achieve its potential ability for enabling high transmission data rate. The various computer simulations are conducted to evaluate the DCTI-CE method in MIMO-OFDM system under the multipath fading channel for wireless LANs.

This paper describes a design of Ogg Vorbis decoder for embedded platform. Since Ogg Vorbis decoding process incurs high computational complexity, a trivial software-based implementation requires high operation frequency. Thus in our design specific hardware modules are devised for functional blocks, which have higher computational complexity than other blocks in Ogg Vorbis decoding process. Based on computational cost analysis of whole decoding process, IMDCT (Inverse Modified Discrete Cosine Transform) and residue decoding process are detected as the computation-intensive functional blocks. As a result of hardware implementation, 73% improvement in CPU load is achieved by specific hardware modules for IMDCT and residue decoding process.

In this letter, we propose a complexity-scalable DCT-based video encoder which works for the highly resource-limited terminals, such as cellular phone, PDA, handheld terminals, etc. The basic concept in the proposed method is for DCT operations to be adaptively changing the complexity like buffer control algorithm in the CBR (Constant Bit-Rate) video encoder.

In this paper, we propose a new one-dimensional (1D) integer discrete cosine transform (Int-DCT) for unified lossless/lossy image compression. The proposed 1D Int-DCT is newly designed to reduce rounding effects by minimizing number of rounding operations. The proposed Int-DCT can be operated not only lossless coding for a high quality decoded image but also lossy coding for a compatibility with the conventional DCT-based coding system. Both theoretical analysis and simulation results confirm an effectiveness of the proposed Int-DCT.

The latest video coding standard, H.264/AVC, adopts 44 approximate transform instead of 88 discrete cosine transform (DCT) to avoid the inverse transform mismatch problem. However, that is only one of the factors that make it difficult to transcode pre-coded video contents with the previous standards to H.264/AVC in the common domain without causing cascaded pixel-domain transcoding. In this paper, to support the existent DCT-domain transcoding schemes and to reduce computational complexity, we propose an efficient algorithm that converts the quantized 88 DCT block into four newly quantized 44 transformed blocks. The experimental results show that the proposed scheme reduces computational complexity by 5-11% and improves video quality by 0.1-0.5 dB compared with the cascaded pixel-domain transcoding scheme that exploits inverse quantization (IQ), inverse DCT (IDCT), DCT, and re-quantization (re-Q).

Recent microprocessors have included SIMD (single instruction multiple data) extensions into their instruction set architecture to improve the performance of multimedia applications. SIMD instructions speed up the execution of programs but pose lots of challenges to software developers. An efficient matrix-based splitter (or merger), which can split an N N 2-D DCT block into four N/2 N/2 or two N N/2 (or N/2 N) 2-D DCT blocks (or merger small size blocks into a large size one), specialized for SIMD architectures is presented in this paper. The programming-level complexity of the proposed methods is lower than that of the direct approach. Furthermore, even without using SIMD instructions, the algorithmic-level complexity of the proposed DCT splitter/merger is still lower than that of the direct one and is the same as that of the most efficient approach existed in the literature. When N = 8, our method can be applied to act as a transcoder between the latest video coding standards AVC/H.264 and the older ones, such as MPEG-1, MPEG-2 and MPEG-4 part 2. We also provide the image quality tests to show the performance of the proposed 2-D DCT splitter and merger.

The rate-distortion optimization (RDO) method is an informative technology that improves the coding efficiency, but increases the computational complexity, of the H.264 encoder. In this letter, a fast Macroblock mode determination algorithm is proposed to reduce the computational complexity of the H.264 encoder. The proposed method reduces the encoder complexity by 55%, while maintaining the same level of coding efficiency.

We propose a novel hierarchical transmission method of DCT coefficients using multi-code DS/SS modulation. For low resolution image transmission over noisy channel, an error resilient and graceful degradation technique is necessary. Here, the DCT coefficients are divided into each stratum (a branch of multi-code DS/SS) and transmitted simultaneously through a noisy channel. By assigning an appropriate transmission energy that corresponds to their source energy variances, energy assignment, it is possible to maintain picture quality effectively even in a noisy channel. Analysis of this method was performed using an image data model, 2-D Gauss-Markov random field, which showed that picture quality is maintained even in the noisy channel condition.

Noise generation systems are used to generate noise signals with specified characteristics. In recent study, noise generation system using DCT outperforms the conventional noise generation system when a noise model requires complicated PSD(Power Spectral Density) specifications. In this paper, low area and low power structures of non-DCT block in DCT-based noise generation system are proposed. Simulation results show that the low area structure results in area reduction by 61-64% and the low power structure achieves power reduction by 88-89% except DCT blocks.

By modelling the quantization error as additive white noise in the transform domain, Wiener filter is used to reduce quantization noise for DCT coded images in DCT domain. Instead of deriving the spectrum of the transform coefficient, a DPCM loop is used to whiten the quantized DCT coefficients. The DPCM loop predicts the mean for each coefficient. By subtracting the mean, the quantized DCT coefficient is converted into the sum of prediction error and quantization noise. After the DPCM loop, the prediction error can be assumed uncorrelated to make the design of the subsequent Wiener filter easy. The Wiener filter is applied to remove the quantization noise to restore the prediction error. The original coefficient is reconstructed by adding the DPCM predicted mean with the restored prediction error. To increase the prediction accuracy, the decimated DCT coefficients in each subband are interpolated from the overlapped blocks.