There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

A scheme is developed for classifying the types of motion perceived by a humanlike robot. It is assumed that the robot receives visual images of the scene using a perspective system model. Equations, theorems, concepts, clues, etc., relating the objects, their positions, and their motion to their images on the focal plane are presented. >

http://ieeexplore.ieee.org/iel2/815/3148/00100651.pdf

Robot vision

In this paper, we develop the nonsubsampled contourlet transform (NSCT) and study its applications. The construction proposed in this paper is based on a nonsubsampled pyramid structure and nonsubsampled directional filter banks. The result is a flexible multiscale, multidirection, and shift-invariant image decomposition that can be efficiently implemented via the a trous algorithm. At the core of the proposed scheme is the nonseparable two-channel nonsubsampled filter bank (NSFB). We exploit the less stringent design condition of the NSFB to design filters that lead to a NSCT with better frequency selectivity and regularity when compared to the contourlet transform. We propose a design framework based on the mapping approach, that allows for a fast implementation based on a lifting or ladder structure, and only uses one-dimensional filtering in some cases. In addition, our design ensures that the corresponding frame elements are regular, symmetric, and the frame is close to a tight one. We assess the performance of the NSCT in image denoising and enhancement applications. In both applications the NSCT compares favorably to other existing methods in the literature

/pdf/the-nonsubsampled-contourlet-transform-theory-design-and-3a4lsit6lx.pdf

The Nonsubsampled Contourlet Transform: Theory, Design, and Applications

https://www.ee.columbia.edu/ln/dvmm/publications/02/louis_survey7.pdf

Survey of compressed-domain features used in audio-visual indexing and analysis

There has been a constant interest in the design and implementation of digital filters with variable characteristics for different applications. In this article an attempt is made to review and systematize all known structures and methods of design of such filters. First the basic theory of the variable digital filters is introduced. Then FIR and IIR realizations with real and complex coefficients are considered, the known results for multidimensional variable filters are discussed and finally, typical implementations are overviewed. Recommendations for applications in different situations are given and unresolved problems are pointed out. This work is basically a review, but some of our original results are also included.

Variable Digital Filters

Two-dimensional (2-D) linear-phase diamond-shaped (DS) FIR digital filters have important image processing applications. They are used in sampling structure conversion, e.g. interlace-to-progressive conversion. Maximally flat (MF) DS filters have attractive time- and frequency-domain properties and are preferred in some applications. In this correspondence MF half-band DS FIR are designed using the two-variable Bernstein polynomial. Formulas for the transfer function and the impulse response are obtained. >

Maximally flat half-band diamond-shaped FIR filters using the Bernstein polynomial

This paper proposes a motion estimation technique to improve accuracy and coherence of motion vectors estimated by the standard block matching technique. The proposed technique is based on a matching block integration using a reliability metric of motion vectors. First, the reliability metric is computed for all the matching blocks in the target image and then, based on this value and its dependency on the direction, four neighboring matching blocks are checked whether they should be integrated or not. Finally, motion vectors are estimated for the integrated matching blocks by the block matching technique. Since the block integration is performed only for flat matching blocks or those with a simple edge, the coherence is improved while the performance of motion compensation is kept as far as possible. The examples given show the effectiveness of the proposed approach.

Block matching motion estimation using block integration based on reliability metric

The use of applications related to real-time video communications is spreading. But it is becoming difficult to secure the bandwidth, because of the increase in the number of the users as well as the bandwidth requirements of each user. In this context, a transcoder that can recode the video data to a usable bit rate for transmission is needed. In order to maintain as high a quality of service as possible, as seen by the user, there must be a criterion for assessment of image quality, by which the amounts of video information in the space and time directions can be reduced with good balance. In the conventional transcoder, control is based mostly on the square error, but it is not always true that the square error can directly represent the video quality seen or subjectively perceived by the user (subjective assessment quality). Consequently, this paper proposes a method of estimating the frame rate (optimal frame rate) that maximizes the subjective assessment quality in the recoding of video data (original data) stored in a video server to a specified bit rate. In the proposed method, the mean opinion score (MOS) obtained by a large number of subjective assessment tests is approximated by a function containing a small number of parameters, and the parameters of the function are estimated on the basis of the features of the original image. By specifying the bit rate for the function, the optimal frame rate is determined by determining the maximum. Interval estimation of the optimal frame rate was performed by applying the proposed method to open data, and it was verified that the frame rate could be estimated with a mean error of approximately 4 frames/s. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 86(12): 54–67, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10102

Toshiyuki Yoshida

Papers

Maximally flat half-band diamond-shaped FIR filters using the Bernstein polynomial

Block matching motion estimation using block integration based on reliability metric

Estimation of the optimal frame rate for video communications under bit-rate constraints

A design method of 2-D maximally flat Diamond-shaped half-band FIR filters

Design of Checkerboard-Distortion-Free Multidimensional Multirate Filters