A 12-bit, two-stage cyclic analog-to-digital converter (ADC) for a 33-megapixel 120-fps CMOS image sensor with low power consumption was developed by analyzing the relationship between the processed bit number and power consumption in the first- and second-stage ADCs, respectively. The power consumption of a two-stage cyclic ADC per column driven at 120 fps was reduced to 101 µW after 12 bits were separated into the upper 4 bits of the conversion in the first-stage ADC and the lower 8 bits of the conversion in the second-stage one. It exhibits a maximum differential non-linearity of -0.7/+0.5 LSB and a random noise of 148.5 µV_rms, both of which are sufficient for the sensor. Owing to the low power consumption ADC, the sensor showed a low power consumption of 2.32 W in conjunction with a high frame rate of 120 fps and a high resolution of 33 Mpixels. The quality of the images taken by the image sensor is good enough for use in full-spec Super Hi-Vision.

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We propose a method for enhancing the contrast of grayscale images by equalizing their weighted histograms on the basis of the gradient norm, and we quantitatively evaluate the effectiveness of the proposed method.

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We present a simple technique for upscaling small pixel-arts. First, an input image is upscaled on the basis of the saliency, i.e., the local majority of each color. The corner of blocks is rounded and jaggy noise on color boundaries is smoothed. Using our method preserves every color in the original image, i.e., smoothes images only geometrically. The upscaling procedure is reversible, i.e., the original pixel-art is easily obtained from the upscaled output. We show with experiments that our method does not produce the unnatural patterns that appear when using the EPX method and the smoothness of edges is also superior.

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We propose a method for generating halftone images from grayscale images based on their integral images. The pixel values of a halftone image are determined so that the errors between the integral image of the halftone image and that of the grayscale image are minimized.

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A novel coding scheme for color video signals in RGB 4:4:4 format is proposed. To exploit inter-color as well as intra-color correlations, the block-adaptive spatio-temporal prediction method is extended in order to use different color signals simultaneously in the prediction process.

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In recent years, Wi-Fi has been attracting attention as a low cost, safe and convenient access technology. Wi-Fi in the United States has been organized as a part of the business strategy of cable operators. In addition, the form of service has changed from wired to wireless, from indoor to outdoor. The AP built-in cable modem has become very popular in the market. Evaluations to realize cable Wi-Fi service have been conducted and cable Wi-Fi services by some cable operators get started in Japan. To provide services such as Internet access with public wireless LAN cable operators, Japan Cable Laboratories completed the technical specifications for cable Wi-Fi with the aim of a unified, common standard in the industry. An evaluation was conducted through field testing to verify subscriber authentication protocol, throughput and signal propagation. We developed operational guidelines relating to the maintenance and operation of Wi-Fi equipment.

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Video quality improvement plays an important role in QoE in video applications. In this paper, we propose a subjective video quality estimation method that can compare subjective video quality in various spatial and temporal resolutions. Our method does not need to encode a video fully other than a few video encodings to estimate the relationship between bitrate and the quantization parameter.

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We have investigated implementation methods for a remote user interface, which enables us to control audio/visual devices such as a DVD/HDD recorder placed in a separate room, but connected through a network. To implement such a system effectively, we have introduced software modules widely used for PCs into an embedded system by using a CPU built in a SOC for a DTV receiver and evaluated performance levels achieved without adding any hardware resource such as RAM. We found that the system embedded in products in current use products works reasonably well for a graphical user interface for home audio/visual devices.

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Portable storage media, such as universal serial bus (USB) ash drives, are used to carry digital data. However, a great deal of data leaks as a result of users forgetting to delete data copied to a personal computer from portable storage media. We propose a technique to detect the remains of copy content files by analyzing the clipboard and directory logs obtained from a personal computer. Our experimental result suggests that the technique can be used to accurately detect files containing copy left behind.

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X-ray intravital microscopy using a microangiography technique was developed at SPring-8 to enable in vivo visualization of coronary arteries for vascular-based functional imaging in rats and mice. Angiographic images of beating hearts were obtained with spatial resolution in the micrometer range and temporal resolution in the millisecond range. Small blood vessels around 50 µm in diameter were visualized clearly. The X-ray intravital microscopy enables direct investigation of vascular functions.

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A novel approach for bit-depth expansion is proposed. When displaying a low bit-depth image on a monitor, false contour artifacts tend to appear in the gradation region. Such false contours seriously degrade the image quality. Reconstructing smooth gradations from false contours is crucial yet it remains difficult problem for 2D images. The proposed method enables the 2D interpolation problem to be separated into a 1D problem by using the Poisson equation. An output image with mathematically smooth gradations can be obtained.

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We have proposed the non-photorealistic rendering method with a bilateral filter for generating roller and moire picture-like images from photographs. We combine these two images to obtain more impressive non-photorealistic rendering effects. By conducting experiments using various images, we show that the resulting combined image reveals a new type of non-photorealistic effects and looks more impressive than roller and moire picture-like images.

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Recently, the electromagnetic environment in the UHF television band has changed significantly in Japan. Digital broadcasting has spread, but radio disturbance occur from spring to fall. This phenomenon is caused by ionospheric propagation of the Es layer or duct propagation in the troposphere. We have steadily observed UHF radio waves at Ishikawa National College of Technology in Tsubata since 2005. UHF radio waves are received from Matsue city and Korea, which are over-the-horizon distances away from Tsubata. Therefore, we researched the relations between the wave receiving statuses of channels 41, 43, and 45 from Matsue city and the season and weather, and we found that we received the most radio waves in summer and in fine weather. Therefore, this phenomenon may be due to the duct propagations in the troposphere.

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The human electroencephalographic (EEG) spectra when looking at the stimuli of a real motion image and motion images at 60- and 240-fps were investigated. The EEG spectra in response to the 240fps stimuli showed a greater level of similarity to those of the real motion image stimuli than to those in response to the 60fps stimuli. This high frame rate image is considered to provide perceptions of motion image quality which are close to the impression gained when looking at real world scenes.

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