Helge Seetzen

High dynamic range display systems

The dynamic range of many real-world environments exceeds the capabilities of current display technology by several orders of magnitude. In this paper we discuss the design of two different display systems that are capable of displaying images with a dynamic range much more similar to that encountered in the real world. The first display system is based on a combination of an LCD panel and a DLP projector, and can be built from off-the-shelf components. While this design is feasible in a lab setting, the second display system, which relies on a custom-built LED panel instead of the projector, is more suitable for usual office workspaces and commercial applications. We describe the design of both systems as well as the software issues that arise. We also discuss the advantages and disadvantages of the two designs and potential applications for both systems.

54.2: A High Dynamic Range Display Using Low and High Resolution Modulators

We have developed an emissive high dynamic range (HDR) display that is capable of displaying a luminance range of 10,000cd/m2 to 0.1cd/m2 while maintaining all features found in conventional LCD displays such as resolution, refresh rate and image quality. We achieve that dynamic range by combining two display systems — a high resolution transmissive LCD and a low resolution, monochrome display composed of high brightness light emitting diodes (LED). This paper provides a description of the technology as well as findings from a supporting psychological study that establishes that correction for the low resolution display through compensation in the high resolution display yields an image which does not differ perceptibly from that of a purely high resolution HDR display.

Ldr2Hdr: on-the-fly reverse tone mapping of legacy video and photographs

New generations of display devices promise to provide significantly improved dynamic range over conventional display technology. In the long run, evolving camera technology and file formats will provide high fidelity content for these display devices. In the near term, however, the vast majority of images and video will only be available in low dynamic range formats. In this paper we describe a method for boosting the dynamic range of legacy video and photographs for viewing on high dynamic range displays. Our emphasis is on real-time processing of video streams, such as web streams or the signal from a DVD player. We place particular emphasis on robustness of the method, and its ability to deal with a wide range of content without user adjusted parameters or visible artifacts. The method can be implemented on both graphics hardware and on signal processors that are directly integrated in the HDR displays.

Photometric image processing for high dynamic range displays

Many real-world scenes contain brightness levels exceeding the capabilities of conventional display technology by several orders of magnitude. Through the combination of several existing technologies, new high dynamic range displays have been constructed recently. These displays are capable of reproducing a range of intensities much closer to that of real environments. We present several methods of reproducing photometrically accurate images on this new class of devices, and evaluate these methods in a perceptual framework.

25.3: Observations of Luminance, Contrast and Amplitude Resolution of Displays

contrast ratio and amplitude resolution are rapidly growing display specifications. Through a series of human factor studies we have developed simple guidelines for these specifications including viewer preference for luminance, optimal contrast ratio and amplitude resolution under realistic conditions. 1. Introduction past, conventional displays have been largely limited to a dynamic range similar to paper under office lighting conditions - approximately two or three orders of magnitude starting at a grayish black and finishing in the hundreds of cd/m 2 . This paradigm of hundreds-to-one contrast ratio, limited luminance and an amplitude resolution in the hundreds of steps is shifting today. Novel display technologies are emerging with the potential of much higher contrast and brightness. Moreover, even existing display technology is being pushed to the limit with a strong increase in display performance. This trend proceeds unevenly with contrast ratio rising faster than luminance, and amplitude resolution remaining largely static. As a result, many display designs make sub-optimal use of the device capabilities. This paper presents a series of human factor studies that aim to provide a basic framework of luminance, contrast ratio and amplitude resolution and their interaction. The use of a High Dynamic Range (HDR) display (1) as the imaging tool for the study, allows a large enough range for each variable to encompass all current and most near-future display technologies. The results of the study can be used to make design decisions for future displays as well as more realistic comparisons of existing devices. 2. Background Video Electronics Standards Association (VESA) and International Organization for Standardization (ISO) provide common guidelines for display specification including luminance and contrast ratio. Peak luminance is generally easy to measure and reported relatively accurately by the industry. Contrast ratio is significantly more challenging. A proper contrast ratio

Self-Calibrating Wide Color Gamut High Dynamic Range Display

High Dynamic Range displays offer higher brightness, higher contrast, better color reproduction and lower power consumption compared to conventional displays available today. In addition to these benefits, it is possible to leverage the unique design of HDR displays to overcome many of the calibration and lifetime degradation problems of liquid crystal displays, especially those using light emitting diodes. This paper describes a combination of sensor mechanisms and algorithms that reduce luminance and color variation for both HDR and conventional displays even with the use of highly variable light elements.

HDR displays: a validation against reality

In the real world the contrast between bright areas, directly illuminated by the sun, and dark shadows can be of 6 or 7 orders of magnitude. Although such huge contrast ratio is common in the natural world when these luminance levels are to be displayed on a typical monitor, the range is far too large. Bright areas appear overly saturated and shadows are displayed as black. Until recently, the only approach to solve this problem was to compress the luminance component of a high dynamic range (HDR) scene. Such techniques are known as tone mapping. However, even tone mapping operators are not always capable of producing sufficient contrast reduction. In this paper we present the results of a psychophysical investigation to validate a novel HDR display which is capable of contrast ratios similar to what is present in the physical world. Images displayed on this device are an accurate representation of a window on a scene and may not be equivalent as standing in the real scene due to a lack of peripheral information. We describe three perceptual studies with the goal of validating the device against real scenes in terms of peripheral vision.

Comparing Signal Detection Between Novel High-Luminance HDR and Standard Medical LCD Displays

DICOM specifies that digital data values should be linearly mapped to just-noticable differences (JNDs) in luminance. Increasing the number of JNDs available requires increasing the displays dynamic range. However, operating over too wide a range may cause human observers to miss contrast in dark regions due to adaptation to bright areas or, alternatively, miss edges in bright regions due to scattering in the eye. Dolby Inc.s high dynamic range (HDR) LCD display has a maximum luminance over 2000 cd/m2; bright enough to produce significant in-eye scatter. The display combines a spatially variable backlight producing a low-resolution 8-bit ldquobacklight imagerdquo with a high-resolution 8-bit LCD panel, approximating a 16-bit greyscale display. Alternatively, by holding the backlight constant at 800 cd/m2, a standard medical LCD display can be simulated.We used two-alternative forced choice (2AFC) signal-detection experiments to quantify display quality. We explored whether the full-power HDR displays optical characteristics (scattering and low resolution backlight) have a negative effect on signal detection in medical images compared with a standard LCD. We used 8-bit test images derived from high-field MRI data combined with synthetic targets and synthetic Rician noise. We suggest signal detection performance with the HDR display is comparable to a standard medical LCD.

3.2: High Dynamic Range Projection Systems

Digital cinema and home theatre applications need to compete with analog film in terms of image quality. The single most important performance specification of a projection system, and the largest gap in the competition between digital and analog projectors, is the relatively low dynamic range of luminance of current digital projectors. In this paper we introduce a novel digital system capable of displaying images with a high enough dynamic range to rival analog film. The projection system described is based on a serial combination of light modulating devices, such as two liquid crystal micro-display panels within a projection light engine. One of the modulation steps can be of lower spatial resolution and contrast. This increases the optical efficiency of the system and avoids optical artifacts. We describe several hardware implementations of this approach as well as the required image processing. Finally, we present an evaluation of the designs in terms of performance, image quality and cost.

Real illumination from virtual environments

We introduce a method for actively controlling the illumination in a room so that it is consistent with a virtual world. In combination with a high dynamic range display, the system produces both uniform and directional illumination at intensity levels covering a wide range of real-world environments. It thereby allows natural adaptation processes of the human visual system to take place, for example when moving between bright and dark environments. In addition, the directional illumination provides additional information about the environment in the users peripheral field of view. We describe both the hardware and the software aspects of our system. We also conducted an informal survey to determine whether users prefer the dynamic illumination over constant room illumination in an entertainment setting.