The Journal of The Institute of Image Information and Television Engineers
Online ISSN : 1881-6908
Print ISSN : 1342-6907
ISSN-L : 1342-6907
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Volume 63, Issue 10
Displaying 1-32 of 32 articles from this issue
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  • Improvement of Photoluminescence Properties in YPO4:Mn2+ Phosphor Codoped with Tetravalent cations
    Mamoru Kitaura
    2009 Volume 63 Issue 10 Pages 1418-1422
    Published: October 01, 2009
    Released on J-STAGE: May 01, 2010
    DOIhttps://doi.org/10.3169/itej.63.1418
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    Photoluminescence (PL) of YPO4:Mn2+ codoped with four tetravalent cations (Zr4+, Sn4+, Ti4+, and Si4+) has been investigated at room temperature under excitation with vacuum ultraviolet (VUV) photons at 147 nm. The wavelength is located at the fundamantal absorption edge of YPO4. The concentration of all the cations was set to be 1.0 mol% in preparation. The PL spectra exhibited a blue-green (BG) band peaking at 482 nm. The PL intensity of the BG band is highest when Zr4+ ions were codoped into YPO4:Mn2+, and thus Zr4+-codoping is the best choice for PL enhancement in YPO4:Mn2+ phosphors. It was found that the PL intensity of Zr4+ doped YPO4:Mn2+ reached 80% of that of a well-known VUV phosphor BaMgAl10O17:Eu2+, unless the concentration of Mn2+ and Zr4+ ions was not optimaized.
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  • Subjective Evaluation for Luminance Non-uniformity of LED Backlight
    Yuko Masakura, Tohru Tamura, Kunihiko Nagamine, Satoshi Tomioka
    2009 Volume 63 Issue 10 Pages 1423-1428
    Published: October 01, 2009
    Released on J-STAGE: May 01, 2010
    DOIhttps://doi.org/10.3169/itej.63.1423
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    The luminance non-uniformity of LED backlight was evaluated by using artificial indistinct Mura images with five different forms, two sizes, and three contrasts. The results show that Mura size and contrast significantly affect the subjective evaluation. Analysis of the relationship between the subjectively evaluated luminance non-uniformity and the luminance distribution characteristics of Mura images showed that the Mura edge areas, low luminance areas, and maximum luminance difference between a Mura and a uniform image are important for predicting a subjective evaluation for luminance non-uniformity of indistinct Mura.
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  • Bit Depth Analysis Based on the Barten Model for High Quality FPDs
    Hisashi Sasaki, Haruhiko Okumura
    2009 Volume 63 Issue 10 Pages 1429-1433
    Published: October 01, 2009
    Released on J-STAGE: May 01, 2010
    DOIhttps://doi.org/10.3169/itej.63.1429
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    We propose a method of bit depth analysis that promotes a deeper understanding of the "45dB curse": a widely accepted but usually misunderstood 45dB PSNR criterion for image compression. Our analysis illustrates useful guidelines to further investigate lowering the cost of high-quality display peripheral devices. The Barten model accurately predicts our 2AFC experimental results.
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  • High Contrast Ratio and Low Power Consumption LCD using Simultaneous Optimization of Backlight Luminance and Gamma Conversion Function
    Masahiro Baba, Ryosuke Nonaka, Goh Itoh, Shigesumi Araki, Seiji Kawagu ...
    2009 Volume 63 Issue 10 Pages 1434-1440
    Published: October 01, 2009
    Released on J-STAGE: May 01, 2010
    DOIhttps://doi.org/10.3169/itej.63.1434
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    In recent years, liquid crystal displays (LCDs) are being increasingly used in various display products, such as cellular phones and televisions, leading to demands for higher image quality and lower power consumption. The contrast ratio of LCDs is, however, lower than that of emissive displays such as organic light-emitting diode ones.
    A novel algorithm for LCD backlight dimming to improve the contrast ratio of LCDs is proposed. Backlight luminance and a gamma conversion function are simultaneously optimized acording to input images by minimizing the sum of squared difference between the ideal gamma characteristic with an infinite contrast ratio and the LCD gamma characteristic with a finite contrast ratio. Furthermore, LCD prototypes that utilized the proposed algorithm were developed, and they had both a high contrast ratio and low power consumption.
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  • Zoom System Realized Using Liquid Crystal Lenses
    Mao Ye, Mika Noguchi, Bin Wang, Susumu Sato
    2009 Volume 63 Issue 10 Pages 1441-1446
    Published: October 01, 2009
    Released on J-STAGE: May 01, 2010
    DOIhttps://doi.org/10.3169/itej.63.1441
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    A zoom lens system with no moving elements is reported. The system is composed of three lenses: one glass lens and two liquid crystal (LC) ones almost identical in structure. The focal length of the LC lenses is tunable from negative to positive with two independent applied voltages. The two LC lenses are placed on two sides of the glass lens, and the positions of all lenses are fixed. The image size is changed and the image position on the CCD image sensor plane is maintained by tuning the focal length of each LC lens. The lens power of the LC lenses ranges from −14.7 to 14.0 m−1. Clear images are obtained at various values of the applied voltages and the zoom ratio is approximately 1:2.
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  • Correction Method of Color-Matching Functions Using Genetic Algorithm and Gaussian Approximation
    Shinnosuke Ozaki, Yuichiro Tokuda, Gosuke Ohashi, Yoshifumi Shimodaira
    2009 Volume 63 Issue 10 Pages 1447-1452
    Published: October 01, 2009
    Released on J-STAGE: May 01, 2010
    DOIhttps://doi.org/10.3169/itej.63.1447
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    Spectrocolorimeters are widely used to adjust the color of items such as LCDs, CRTs, projectors, and other video equipment. However, the color appearance of one display is sometimes mismatched with that of another display, even though the colorimetric values of the two - which are measured at the same time and under the same illumination - have been matched. It has been reported that the gap between color-matching functions and the human perception of color causes this phenomenon. The purpose of this study was to correct color-matching functions to reduce the gap between colorimetric values and human perception of color. Color-matching functions were approximated by Gaussian functions, which were controlled by ten parameters. The parameters were optimized using genetic algorithm to minimize color differences between the colorimetric values of the supervised data. Results show that the perceptual color matching was improved.
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  • Rendering Arbitrary Viewpoint Images from Image Cluster
    Siren Batu, Yoshinori Dobashi, Tsuyoshi Yamamoto
    2009 Volume 63 Issue 10 Pages 1453-1458
    Published: October 01, 2009
    Released on J-STAGE: May 01, 2010
    DOIhttps://doi.org/10.3169/itej.63.1453
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    We propose a new, simple, and effective image-based rendering technique for synthesizing images of novel views from an image cluster, a large volume of precaptured images randomly distributed in a bounded region with known camera positions and orientations. Unlike methods that are based on sampling, and constructing and resampling the plenoptic function, our method uses a select and warp approach. We use scene depth information as additional input to render novel views from an image cluster that has fewer images than that used in plenoptic function based approaches. Furthermore, unlike the view interpolation approach that typically uses a small number of input images our method deals with large number, typically from several hundred to several thousand. Our method involves finding the optimal pixel from the input image cluster on the assumption that as the image is dense enough and as each pixel needed is visible from at least one of the input images, no occlusion occurs.
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  • Model-Based Analysis and Synthesis of Time-Varying Meshes by Extracting Skeleton Structure
    Toshihiko Yamasaki, Takashi Maeda, Suguru Nakagawa, Kiyoharu Aizawa
    2009 Volume 63 Issue 10 Pages 1459-1466
    Published: October 01, 2009
    Released on J-STAGE: May 01, 2010
    DOIhttps://doi.org/10.3169/itej.63.1459
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    Time-varying mesh (TVM), a technique that is used to describe the full shape and motion of a real-world moving object, precisely captures and reproduces human behavior and natural movements (such as the expression of a face or small changes in clothing). Unfortunately, TVM requires a large storage space and has a high computational cost. To solve this problem, we developed a framework of motion editing and synthesis aimed at rendering on mobile devices in particular, in which the computational resources are severely limited. In our approach, a skeleton model is extracted from each frame and motion tracking and analysis are conducted using the skeleton models. Then, a key frame is deformed based on the extracted motion information. This results in a 3D scene representation with a much smaller data size. The motion of the TVM model can also be controlled by using motion capture data. Experimental results showed that the data size can be reduced from 650 MB to 14 MB. In addition, subjective evaluation demonstrated that the proposed approach is appropriate for small-size display while maintaining a reasonable rendering quality.
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  • Apparent Motion and Visible-Band Motion
    -The Basis of Signal Processing of Visual Perception-
    Takahiko Fukinuki
    2009 Volume 63 Issue 10 Pages 1467-1469
    Published: October 01, 2009
    Released on J-STAGE: May 01, 2010
    DOIhttps://doi.org/10.3169/itej.63.1467
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    Sampled motion in TV and movies, e.g., has been considered to be apparent motion (AM) . Here in this paper, it is emphasized that these two motions are completely different, and the former is named "visible-band motion (VBM) ". In the VBM, real motion components exist in the visible-band in the spatio-temporal frequency domain, while the AM may be due to brain's higher functions. Hence, these two should be studied as complete different phenomena for the future expansion.
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  • Why is Sampled Motion Possible?
    Takahiko Fukinuki
    2009 Volume 63 Issue 10 Pages 1470-1472
    Published: October 01, 2009
    Released on J-STAGE: May 01, 2010
    DOIhttps://doi.org/10.3169/itej.63.1470
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    Although sampled motion in TV and movies has been considered to be self-evident, it does not seem to satisfy the sampling theory. Here, the fundamental properties of TV signals in the spatio-temporal domain are rather different from those in the horizontal-vertical domain. By analyzing the motion in the spatio-temporal frequency domain with assumption of these properties and those of an eye system, it is made clear that the motion satisfies the theorem.
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