The Experts below are selected from a list of 426 Experts worldwide ranked by ideXlab platform

Philipp Urban - One of the best experts on this subject based on the ideXlab platform.

  • toward a unified color space for perception based image processing
    IEEE Transactions on Image Processing, 2012
    Co-Authors: Ingmar Lissner, Philipp Urban
    Abstract:

    Image processing methods that utilize characteristics of the human visual system require color spaces with certain properties to operate effectively. After analyzing different types of perception-based image processing problems, we present a list of properties that a unified color space should have. Due to contradictory Perceptual phenomena and geometric issues, a color space cannot incorporate all these properties. We therefore identify the most important properties and focus on creating opponent color spaces without cross contamination between color attributes (i.e., lightness, chroma, and hue) and with maximum Perceptual Uniformity induced by color-difference formulas. Color lookup tables define simple transformations from an initial color space to the new spaces. We calculate such tables using multigrid optimization considering the Hung and Berns data of constant perceived hue and the CMC, CIE94, and CIEDE2000 color-difference formulas. The resulting color spaces exhibit low cross contamination between color attributes and are only slightly less Perceptually uniform than spaces optimized exclusively for Perceptual Uniformity. We compare the CIEDE2000-based space with commonly used color spaces in two examples of perception-based image processing. In both cases, standard methods show improved results if the new space is used. All color-space transformations and examples are provided as MATLAB codes on our website.

Ingmar Lissner - One of the best experts on this subject based on the ideXlab platform.

  • toward a unified color space for perception based image processing
    IEEE Transactions on Image Processing, 2012
    Co-Authors: Ingmar Lissner, Philipp Urban
    Abstract:

    Image processing methods that utilize characteristics of the human visual system require color spaces with certain properties to operate effectively. After analyzing different types of perception-based image processing problems, we present a list of properties that a unified color space should have. Due to contradictory Perceptual phenomena and geometric issues, a color space cannot incorporate all these properties. We therefore identify the most important properties and focus on creating opponent color spaces without cross contamination between color attributes (i.e., lightness, chroma, and hue) and with maximum Perceptual Uniformity induced by color-difference formulas. Color lookup tables define simple transformations from an initial color space to the new spaces. We calculate such tables using multigrid optimization considering the Hung and Berns data of constant perceived hue and the CMC, CIE94, and CIEDE2000 color-difference formulas. The resulting color spaces exhibit low cross contamination between color attributes and are only slightly less Perceptually uniform than spaces optimized exclusively for Perceptual Uniformity. We compare the CIEDE2000-based space with commonly used color spaces in two examples of perception-based image processing. In both cases, standard methods show improved results if the new space is used. All color-space transformations and examples are provided as MATLAB codes on our website.

Rick Stevens - One of the best experts on this subject based on the ideXlab platform.

  • Perceptual Photometric Seamlessness in Projection-Based Tiled Displays
    2013
    Co-Authors: Aditi Majumder, Rick Stevens
    Abstract:

    Arguably, the most vexing problem remaining for multi-projector displays is that of photometric (brightness) seamlessness within and across different projectors. Researchers have strived for strict photometric Uniformity that achieves identical response at every pixel of the display. However, this goal typically results in displays with severely compressed dynamic range and poor image quality. In this paper, we show that strict photometric Uniformity is not a requirement for achieving photometric seamlessness. We introduce a general goal for photometric seamlessness by defining it as an optimization problem balancing Perceptual Uniformity with display quality. Based on this goal, we present a new method to achieve Perceptually seamless high quality displays. We first derive a model that describes the photometric response of projection-based displays. Then we estimate the model parameters and modify them using perception-driven criteria. Finally, we use the graphics hardware to reproject the image computed using the modified model parameters by manipulating only the projector inputs at interactive rates. Our method has been successfully demonstrated on three different practical display systems at Argonne National Laboratory, made of 2 × 2 array of four projectors, 2 × 3 array of six projector

  • Perceptual photometric seamlessness in projection-based tiled displays
    2005
    Co-Authors: Aditi Majumder, Rick Stevens
    Abstract:

    Arguably, the most vexing problem remaining for multi-projector displays is that of photometric (brightness) seamlessness within and across different projectors. Researchers have strived for strict photometric Uniformity that achieves identical response at every pixel of the display. However, this goal typically results in displays with severely compressed dynamic range and poor image quality. In this paper, we show that strict photometric Uniformity is not a requirement for achieving photometric seamlessness. We introduce a general goal for photometric seamlessness by defining it as an optimization problem balancing Perceptual Uniformity with display quality. Based on this goal, we present a new method to achieve Perceptually seamless high quality displays. We first derive a model that describes the photometric response of projection-based displays. Then we estimate the model parameters and modify them using perception-driven criteria. Finally, we use the graphics hardware to reproject the image computed using the modified model parameters by manipulating only the projector inputs at interactive rates. Our method has been successfully demonstrated on three different practical display systems at Argonne National Laboratory, made of 2 × 2 array of four projectors, 2 × 3 array of six projectors and 3 × 5 array of fifteen projectors. Our approach is efficient, automatic and scalable – requiring only a digital camera and a photometer. To the best of our knowledge, this is the first approach and system that addresses the photometric variation problem from a Perceptual stand point and generates truly seamless displays with high dynamic range

Aditi Majumder - One of the best experts on this subject based on the ideXlab platform.

  • Perceptual Photometric Seamlessness in Projection-Based Tiled Displays
    2013
    Co-Authors: Aditi Majumder, Rick Stevens
    Abstract:

    Arguably, the most vexing problem remaining for multi-projector displays is that of photometric (brightness) seamlessness within and across different projectors. Researchers have strived for strict photometric Uniformity that achieves identical response at every pixel of the display. However, this goal typically results in displays with severely compressed dynamic range and poor image quality. In this paper, we show that strict photometric Uniformity is not a requirement for achieving photometric seamlessness. We introduce a general goal for photometric seamlessness by defining it as an optimization problem balancing Perceptual Uniformity with display quality. Based on this goal, we present a new method to achieve Perceptually seamless high quality displays. We first derive a model that describes the photometric response of projection-based displays. Then we estimate the model parameters and modify them using perception-driven criteria. Finally, we use the graphics hardware to reproject the image computed using the modified model parameters by manipulating only the projector inputs at interactive rates. Our method has been successfully demonstrated on three different practical display systems at Argonne National Laboratory, made of 2 × 2 array of four projectors, 2 × 3 array of six projector

  • Perceptual photometric seamlessness in projection-based tiled displays
    2005
    Co-Authors: Aditi Majumder, Rick Stevens
    Abstract:

    Arguably, the most vexing problem remaining for multi-projector displays is that of photometric (brightness) seamlessness within and across different projectors. Researchers have strived for strict photometric Uniformity that achieves identical response at every pixel of the display. However, this goal typically results in displays with severely compressed dynamic range and poor image quality. In this paper, we show that strict photometric Uniformity is not a requirement for achieving photometric seamlessness. We introduce a general goal for photometric seamlessness by defining it as an optimization problem balancing Perceptual Uniformity with display quality. Based on this goal, we present a new method to achieve Perceptually seamless high quality displays. We first derive a model that describes the photometric response of projection-based displays. Then we estimate the model parameters and modify them using perception-driven criteria. Finally, we use the graphics hardware to reproject the image computed using the modified model parameters by manipulating only the projector inputs at interactive rates. Our method has been successfully demonstrated on three different practical display systems at Argonne National Laboratory, made of 2 × 2 array of four projectors, 2 × 3 array of six projectors and 3 × 5 array of fifteen projectors. Our approach is efficient, automatic and scalable – requiring only a digital camera and a photometer. To the best of our knowledge, this is the first approach and system that addresses the photometric variation problem from a Perceptual stand point and generates truly seamless displays with high dynamic range

Sabine Süsstrunk - One of the best experts on this subject based on the ideXlab platform.