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[Author] Soo-Wook JANG(7hit)

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  • Chromatic Adaptation Model Using the Relationship between the Cone Responses under Change in Illuminants

    Bong-Soo KIM  In-Ho SONG  Eun-Su KIM  Sung-Hak LEE  Soo-Wook JANG  Kyu-Ik SOHNG  

     
    LETTER

      Vol:
    E89-A No:6
      Page(s):
    1717-1719

    In this paper, a chromatic adaptation model (CAM) based on the dependence on LMS cone responses of the human visual system (HVS) is proposed for TV and PC monitors under a variety of viewing conditions. We derived the proposed CAM based on Breneman's corresponding color data. The results of the experiments were carried out to assess the proposed model performance in terms of color fidelity by comparing complex images on a LCD monitor. We confirmed that the proposed model performed better to predict corresponding colors under various viewing conditions. Therefore, the reproduced colors, which are viewed in real surround viewing conditions, are perceived the same as original object colors, when the proposed CAM was applied to color display devices such as CRT, LCD, and PDP.

  • The Quantitative Model for Optimal Threshold and Gamma of Display Using Brightness Function

    Sung-Hak LEE  Soo-Wook JANG  Eun-Su KIM  Kyu-Ik SOHNG  

     
    LETTER

      Vol:
    E89-A No:6
      Page(s):
    1720-1723

    We investigated physical conditions for optimum display systems on various TV viewing conditions, and found that visual brightness function could be derived from relationships between Steven's power law and Bartleson-Breneman's brightness function, and that the optimum physical contrast ratio and compensated gamma for display system with adaptation luminance level could be obtained from the proposed brightness function.

  • Corresponding-Color Reproduction Model According to Surround Viewing Conditions

    Eun-Su KIM  Soo-Wook JANG  Yong-Dae KWON  Chan-Ho HAN  Kyu-Ik SOHNG  

     
    LETTER

      Vol:
    E87-A No:6
      Page(s):
    1514-1519

    In this paper, a simple and practical corresponding-color reproduction model based on the chromatic adaptation of the human visual system (HVS), named a modified von Kries chromatic-adaptation model, is proposed for TV and PC monitors under a variety of viewing conditions. We derived the proposed corresponding-color reproduction model based on Breneman's corresponding-color data. The proposed model has a 1-2% less error than Fairchild's and Breneman's model, 11.5% less error than von Kries' model and 60% less error than CIECAM97s' model in terms of color reproduction errors, (). Also, these tendency is similar in color reproduction errors, . We implemented a corresponding-color reproduction system using the proposed model under a variety of viewing conditions. For the determination of viewing conditions, illuminant correlated color temperatures (CCTs) are measured by yellow/cyan sensors. These measured surround illuminant CCTs can estimate an adaptated neutral point of the HVS in TV viewing conditions. Experiments were carried out to assess the proposed model performance in terms of color fidelity by comparing complex images on a LCD monitor under illuminants from 2500 K to 7500 K. We confirmed that the implemented system using the proposed model can predict corresponding-color data very well under a variety of viewing conditions. Therefore, by applying the proposed model and system to the LCD, the reproduction colors viewed in real surrounding viewing conditions on the LCD could appear the same as the original object colors under standard viewing conditions. Furthermore, they could be applied to any other color display device such as a CRT, a PDP, and a DLP in order to get better reproduction colors.

  • Improvement of Gray Scale CCT for Mobile Phone LCD

    In-Ho SONG  Bong-Soo KIM  Eun-Su KIM  Sung-Hak LEE  Soo-Wook JANG  Kyu-Ik SOHNG  

     
    LETTER

      Vol:
    E89-A No:6
      Page(s):
    1724-1726

    Color reproductions in most LCD are quite different from those of standard CRT (cathode ray tube) monitor display because of the nonlinear characteristic in subtractive color reproduction. Moreover, gray scale CCT (correlated color temperature) reproductions in a typical mobile phone LCD depend on the input RGB levels. A simple LUT (Look-up table) method for constant gray scale CCT and gamma characteristic of mobile phone LCD is presented in this paper. We investigate the mobile phone LCD's characteristic of compensation of CCT with using the LUT. LCD's CCT is maintaining about 7500 K, which is the target CCT of mobile phone LCD in this paper. Also LCD's gamma is similar to target gamma.

  • The Design of an LCD System Based on the Quantitative Analysis for Enhancement of the Motion Picture Quality

    Sung-Hak LEE  Soo-Wook JANG  Eun-Su KIM  Sang-Hoon LEE  Kyu-Ik SOHNG  

     
    LETTER

      Vol:
    E88-C No:11
      Page(s):
    2094-2098

    The pulsed backlight system has been introduced for reducing motion blurs of LCDs in high motion pictures. But applying the pulsed backlight, full screen flicker and inconsistency of transmissivity for entire frame at a lightening time should be considered. This paper discusses the analysis of blurs in high motion pictures and proposes the design method for more suitable display terminal of LCDs.

  • Optimal Piece Linear Segments of Gamma Correction for CMOS Image Sensors

    Eun-Su KIM  Soo-Wook JANG  Sung-Hak LEE  Tae-Young JUNG  Kyu-Ik SOHNG  

     
    LETTER

      Vol:
    E88-C No:11
      Page(s):
    2090-2093

    The gamma correction for the CMOS image sensors are implemented by the method of piecewise linear approximation through a look-up table. In this paper, we propose a quantitative criterion to select the piece linear segment with the same output interval for the reduction of the error between the value of piece linear approximation and gamma correction. After the gamma correction is implemented, the average error occurred by implementing color interpolation in each segment is a basis for the optimum selecting of the piece linear segment of the gamma correction for the CMOS image sensors.

  • Adaptive Colorimetric Characterization of Camera for the Variation of White Balance

    Eun-Su KIM  Sung-Hak LEE  Soo-Wook JANG  Kyu-Ik SOHNG  

     
    LETTER

      Vol:
    E88-C No:11
      Page(s):
    2086-2089

    The RGB signals generated by different cameras are not equal for the same scene. Therefore, cameras are characterized based on a CIE standard colorimetric observer. One method of deriving a colorimetric characterization matrix between camera RGB output signals and CIE XYZ tristimulus values is least squares polynomial modeling. Yet, this involves tedious experiments to obtain a camera transfer matrix under various white balance points for the same camera. Accordingly, the current paper proposes a new method for obtaining camera transfer matrices under different white balances using a 33 camera transfer matrix under a specific white balance point.