2月号に引き続き, ITU-R SG6の最近の動向について紹介する.今号では, ITU-Rの重要な役割である周波数関係を取り上げ, SG6として活動を進めている, 地上放送, 衛星放送などの, 周波数, 伝送に関する最近のトピックを中心に述べる.また, 中短波放送については, 特にデジタル放送方式として, ITU-Rの標準方式となっているDRM方式について解説を行う.

抄録全体を表示

We have been developing a new image sensor with a field emitter array and a high-gain avalanche rushing amorphous photoconductor (HARP) target, with the aim of using it in ultrahigh-sensitivity, high-resolution compact TV cameras. We fabricated and tested 256 × 192 pixel sensor with a pixel size of 50 × 50μm and its electron-beam focusing system consisting of permanent magnets. Experiments showed that the prototype sensor has both enough resolution for its pixel size and high sensitivity due to the HARP target, thus demonstrating its potential as a practical image sensor.

抄録全体を表示

Readers of e-Books read words on electronic paper. We conducted an experiment in which 13 college students read electronic paper and conventional paper for 90 minutes better understand the degree of visual fatigue from such reading. The degree of their visual fatigue was measured before, during, and after reading. Results showed no significant differences in the levels of visual fatigue between the electronic and conventional reading. We conclude that electronic paper is a good reading display that is as gentle to the eyes as conventional paper.

抄録全体を表示

We used optical low-pass filters with solid-state imaging devices to produce images. The actual optical low-pass filter was formed by combining two types of doubly refractive crystal devices. The filters cannot sharply cut-off the high frequency components and they reduce the frequency components near the Nyquist frequency. Thus, the projected images on the surface are blurred. This paper presents a demosaicking method that restores the blur caused by optical low-pass filters. Our sharpening approach to demosaicking employs a Landweber-type iterative algorithm. For our sharpening-demosaicking approach, the Bayer's pattern of the RGB primary color filter array is not applicable. Therefore, we studied another color-filter pattern, namely the WRB filter array, which is preferable to the RGB filter array, where W-filtering means that all the visible light passes through it. Our mathematical formulations for sharpening-demosaicking are similar to the least square problem, but there are many different least square solutions. To avoid ambiguity in the spatial frequency domain, we introduced a pass-band limitation that corresponds with the sub-sampling pattern of the mosaicking of color filters into the iterative algorithm.

抄録全体を表示

We propose a new method for canceling the fixed-pattern noise in CIVIOS image sensors caused by the threshold mismatch of MOSFETs in pixel circuits. This method uses non-destructive intermediate readout circuitry. We designed a CMOS image sensor in which the canceling circuit was implemented in each column of the pixel-sensor array using a 0.25μm CMOS process. Results from simulations and actual measurements taken revealed that our method would be effective in canceling fixed-pattern-noise in CIVIOS image sensors caused by the threshold mismatch.

抄録全体を表示

Thermosaic is an automatic method of adding obscure effects onto video sequences using thermal information. This is based on the thermo-key technology which is a robust real-time method of human region segmentation. Thermosaic can provide blurring or obscure mosaic effect onto the human regions automatically. This feature is very useful for protecting privacy of people in the video. Meanwhile, Thermosaiccan blur only the background regions. This is good for facial image communication to save the amount of data. This paper presents the concept and concrete implementations of Thermosaic.

抄録全体を表示

There has been research conducted on the reflection and refraction of light using the ray tracing method and the caustics method as techniques for expressing light in computer graphics. However, there has been very little research conducted on the diffraction of light by the gratings. Authors have uniformly expressed a two-dimensional diffraction grating, simulating Raman-Nath diffraction. We propose diffraction by grating with an arbitrary pattern using the bitmap image as the pattern file.

抄録全体を表示

A watermarking scheme that varies the coefficient is described. A watermark element is embedded in the scheme, according to blocks. This scheme generates watermarked images with a desired objective image quality in terms of the peak signal-to-noise ratio, and it extracts an embedded watermark without any reference images. The proposed scheme can change the.subjective image quality of a watermarked image independent of the objective image quality by selecting the coefficient for embedding according to the blocks. However, malicious detection of the embedding coefficients becomes difficult.

抄録全体を表示

This paper proposes an objective measurement for coded video quality based on camera work and frame quality. The same technique used in the objective measurement for coded still image is used to evaluate the frame quality. The proposed measurement also automatically detects the camera work. Experimental results showed that the estimation accuracy for the proposed measurement is improved. In particular, in the case of a still scene, the accuracy is improved greatly.

抄録全体を表示

Color moire, a disturbance caused by the structure of the display panel's color filter, is a problem in the development of viable Integral Photography systems, such as Integral 3DTV. This report introduces several methods to reduce these disturbances, and quantitatively examines their effectiveness and influence on the resolution of displayed images. As a result, we demonstrate the effectiveness of a method that uses a combination of diffusers and defocusing.

抄録全体を表示

We have been developing a method for capturing high quality texture images of 3-D backgrounds for Image-based Virtual Studios, and have actually developed an experimental Robot-Arm Camera system for capturing texture images in a real studio set. This system controls the position and direction of the camera in accordance with the CAD data of the studio set. The camera images are captured in several camera positions and directions in the studio set. The camera images closest to the normal vector of the polygon of each surface are selected, and the textures are produced for each polygon. Although the geometric error of the CAD data and the camera position data affects texture accuracy, experimental results showed that the system is capable of creating high-resolution textures for each polygon.

抄録全体を表示

Because of the availability of the internet and digital cameras, the opportunities to enjoy dynamic images and photographs on PC monitors have increased. A cathode with a convex surface has been studied for large screen (i.e. 22in.) high brightness (i.e. 300cd/m²) PC-CRTs. The dimensions of the convex surface were optimized using computer simulations. We obtained an emission current of 1, 300μA, required for 300cd/m² luminance 22-in. CRTs, with less than a 50-V drive voltage and improved the emittance. We verified significant improvements in the drive and focus characteristics have been verified by prototype CRTs.

抄録全体を表示

We quantitatively analyzed the real cause of convergence fluctuations in power-saved rectangular cone deflection yokes, and we found that minimizing the manufacturing deviations of the ferrite core lessened the convergence fluctuations. By using magnetic field simulations of several types of deflection yokes in addition to the above analysis, we solved the problems of power saving and convergence fluctuations. Additionally, we proved that this idea could be applied to large sizes and wide-angle deflection yokes for TV. Furthermore, we established an accurate power estimation method that is essential to the power-saving system.

抄録全体を表示