[서평]「Digital Video Processing」

How Many People Can the Earth Support? By Joel E. Cohen. Norton: 1995. Pp. 532. $30, £22.50. UK publication date, 27 March.

Book of numbers

This manuscript describes a number of algorithms that can be used to quickly evaluate a polynomial over a collection of points and interpolate these evaluations back into a polynomial. Engineers define the “Fast Fourier Transform” as a method of solving the interpolation problem where the coefficient ring used to construct the polynomials has a special multiplicative structure. Mathematicians define the “Fast Fourier Transform” as a method of solving the evaluation problem. One purpose of the document is to provide a mathematical treatment of the topic of the “Fast Fourier Transform” that can also be understood by someone who has an understanding of the topic from the engineering perspective.
The manuscript will also introduce several new algorithms that solve the fast multipoint evaluation problem over certain finite fields and require fewer finite field operations than existing techniques. The document will also demonstrate that these new algorithms can be used to multiply polynomials with finite field coefficients with fewer operations than Schonhage's algorithm in most circumstances.
A third objective of this document is to provide a mathematical perspective of several algorithms which can be used to multiply polynomials of size which is not a power of two. Several improvements to these algorithms will also be discussed.
Finally, the document will describe several applications of the “Fast Fourier Transform” algorithms presented and will introduce improvements in several of these applications. In addition to polynomial multiplication, the applications of polynomial division with remainder, the greatest common divisor, decoding of Reed-Solomon error-correcting codes, and the computation of the coefficients of a discrete Fourier Series will be addressed.

/pdf/fast-fourier-transform-algorithms-with-applications-2vinpci6f6.pdf

Fast fourier transform algorithms with applications

This paper describes a passive stereo system for capturing the 3D geometry of a face in a single-shot under standard light sources. The system is low-cost and easy to deploy. Results are submillimeter accurate and commensurate with those from state-of-the-art systems based on active lighting, and the models meet the quality requirements of a demanding domain like the movie industry. Recovered models are shown for captures from both high-end cameras in a studio setting and from a consumer binocular-stereo camera, demonstrating scalability across a spectrum of camera deployments, and showing the potential for 3D face modeling to move beyond the professional arena and into the emerging consumer market in stereoscopic photography. Our primary technical contribution is a modification of standard stereo refinement methods to capture pore-scale geometry, using a qualitative approach that produces visually realistic results. The second technical contribution is a calibration method suited to face capture systems. The systemic contribution includes multiple demonstrations of system robustness and quality. These include capture in a studio setup, capture off a consumer binocular-stereo camera, scanning of faces of varying gender and ethnicity and age, capture of highly-transient facial expression, and scanning a physical mask to provide ground-truth validation.

High-quality single-shot capture of facial geometry

IEEE International Conference on Image Processing

One-bit transform (1BT)- and two-bit transform (2BT)-based block motion estimation (ME) schemes have been proposed in the literature to reduce the computational complexity of the ME process by enabling simple Boolean ex-or matching of lower bit depth representations of image frames. Recently a multiplication-free 1BT (MF-1BT) has been proposed to facilitate 1BT to be carried out with integer arithmetic using addition and shifts only. Thresholding schemes are typically used in order to construct the lower bit depth representations utilized in 1BT and 2BT. In our experience we have observed that one problem with such schemes is that pixel values that lie on directly opposite sides of the threshold are categorized into separate classes and are, therefore, counted as a nonmatch in the search process even if they are close in value. A constrained 1BT (C-1BT) that restricts pixels with values adjacent to the transform threshold during 1BT matching, counting them as a match regardless of their 1BT value, is proposed in this paper. It is shown that the proposed C-1BT approach improves the ME accuracy of 1BT-based ME and even outperforms 2BT-based ME at macroblock level

/pdf/constrained-one-bit-transform-for-low-complexity-block-36v8tfmw6x.pdf

Constrained One-Bit Transform for Low Complexity Block Motion Estimation

This paper targets hard-cut detection for archive film, i.e., mainly black-and-white videos from the beginning of the last century, which is a particularly difficult task due to heavy visual degradations encountered in the sequences. A robust hard-cut detection system based on modified phase correlation is presented. Phase-correlation-based hard-cut detection is carried out using spatially sub-sampled video frames, and a candidate hard-cut is indicated in the case of low correlation. A double thresholding approach consisting of a global threshold used in conjunction with an adaptive local threshold is used to detect candidate hard-cuts. For uniformly colored video frames the phase correlation is extremely sensitive to noise and visual defects. Mean and variance based simple heuristic false removal at uniformly colored video frames is used at the final stage to prevent false detections in such cases. The paper provides a through theoretical analysis to show the usefulness of spatial sub-sampling. Furthermore through experimental results are presented for visual defects encountered in archive film material, to present the effectiveness of the proposed approach.

/pdf/modified-phase-correlation-based-robust-hard-cut-detection-555nchpf1e.pdf

Modified phase-correlation based robust hard-cut detection with application to archive film

In this paper, we present efficient hardware implementation of multiplication free one-bit transform (MF1BT) based and constraint one-bit transform (C-1BT) based motion estimation (ME) algorithms, in order to provide low bit-depth representation based full search block ME hardware for real-time video encoding. We used a source pixel based linear array (SPBLA) hardware architecture for low bit depth ME for the first time in the literature. The proposed SPBLA based implementation results in a genuine data flow scheme which significantly reduces the number of data reads from the current block memory, which in turn reduces the power consumption by at least 50% compared to conventional 1BT based ME hardware architecture presented in the literature. Because of the binary nature of low bit-depth ME algorithms, their hardware architectures are more efficient than existing 8 bits/pixel representation based ME architectures.

/pdf/efficient-hardware-implementations-of-low-bit-depth-motion-58jy8bhd6q.pdf

Efficient Hardware Implementations of Low Bit Depth Motion Estimation Algorithms

A computer vision-based approach to drilling tool condition monitoring is proposed in this paper Firstly, image frames are captured using a high-speed CCD camera Then, a Canny edge detector is employed to extract tool features from the acquired images In order to obtain a measure of tool wear, the deviation from linearity (DEFROL) metric is proposed Experimental results show that the proposed method detects the condition of all tested tools successfully

A computer vision-based fast approach to drilling tool condition monitoring

We combine predictive hexagonal pattern and partial distortion searches with the recently proposed constrained one-bit transform-based motion estimation scheme to reduce the computational load of the motion estimation process. Furthermore, the kernel used to obtain the one-bit images is simplified. Experimental results show significant reduction of the number of average search points, with only a slight loss in motion estimation accuracy.

http://kulis.kocaeli.edu.tr/pub/jei07_c1bthexme.pdf

Oguzhan Urhan

Papers

Constrained One-Bit Transform for Low Complexity Block Motion Estimation

Modified phase-correlation based robust hard-cut detection with application to archive film

Efficient Hardware Implementations of Low Bit Depth Motion Estimation Algorithms

A computer vision-based fast approach to drilling tool condition monitoring

Constrained one-bit transform-based motion estimation using predictive hexagonal pattern