Lorne A. Whitehead

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.

Split‐ring resonator for use in magnetic resonance from 200–2000 MHz

A novel high Q resonator is described that is suitable for magnetic resonance in the frequency region 200–2000 MHz, where ordinary cavities are generally too bulky and solenoidal coils impractical.

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.

New efficient light guide for interior illumination

Experimental and theoretical studies of the recently patented prism light guide are described [L. A. Whitehead, U.S. Patent 4,260,220 (7 Apr. 1981)]. This device combines the total internal reflection of optical fibers with the low attenuation of air transmission of light. Since it can be moulded from acrylic plastic, the cost of the guide is low enough to make large-scale interior illumination with piped light feasible.

CRI2012: A proposal for updating the CIE colour rendering index

The CIE colour rendering index (CRI) has been criticized for its poor correlation with the visual colour rendering of many spiked or narrowband sources, its outdated colour space and chromatic adaptation transform and the use of a small number of non-optimal reflectance samples that have enabled lamp manufacturers to tune the spectrum of a light source to yield, in some cases, inappropriately high general CRI values. The CRI2012 metric proposed in this paper addresses these criticisms by combining the most state of the art colorimetric colour difference model, i.e. CAM02-UCS, with a mathematical reflectance set that exhibits a highly uniform spectral sensitivity. A set of 210 real reflectance samples has also been selected to provide additional information on the expected colour shifts when changing illumination.

Simplified ray tracing in cylindrical systems

A simplified method of ray tracing in cylindrical optical systems of arbitrary cross section is described. The technique involves the projection of a rays path onto a cross-sectional plane perpendicular to the axis of translational symmetry. It is shown that this projected path obeys a generalized form of Snells law, enabling application of conventional 2-D ray tracing methods. The approach is illustrated by demonstrating the optical characteristics of the recently patented prism light guide.

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.