Digital Color Imaging
TL;DR: A survey of color imaging can be found in this article, where the fundamental concepts of color perception and measurement are first presented us-ing vector-space notation and terminology, along with common mathematical models used for representing these devices.
Abstract: This paper surveys current technology and research in the area of digital color imaging. In order to establish the background and lay down terminology, fundamental concepts of color perception and measurement are first presented us-ing vector-space notation and terminology. Present-day color recording and reproduction systems are reviewed along with the common mathematical models used for representing these devices. Algorithms for processing color images for display and communication are surveyed, and a forecast of research trends is attempted. An extensive bibliography is provided.
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TL;DR: This work demonstrates a convenient, versatile approach to dynamically fine-tuning emission in the full colour range from a new class of core-shell upconversion nanocrystals by adjusting the pulse width of infrared laser beams and suggests that the unprecedented colour tunability from these nanocry crystals is governed by a non-steady-state upconverting process.
Abstract: Developing light-harvesting materials with tunable emission colours has always been at the forefront of colour display technologies. The variation in materials composition, phase and structure can provide a useful tool for producing a wide range of emission colours, but controlling the colour gamut in a material with a fixed composition remains a daunting challenge. Here, we demonstrate a convenient, versatile approach to dynamically fine-tuning emission in the full colour range from a new class of core-shell upconversion nanocrystals by adjusting the pulse width of infrared laser beams. Our mechanistic investigations suggest that the unprecedented colour tunability from these nanocrystals is governed by a non-steady-state upconversion process. These findings provide keen insights into controlling energy transfer in out-of-equilibrium optical processes, while offering the possibility for the construction of true three-dimensional, full-colour display systems with high spatial resolution and locally addressable colour gamut.
777 citations
TL;DR: This article presents an overview of existing map processing techniques, bringing together the past and current research efforts in this interdisciplinary field, to characterize the advances that have been made, and to identify future research directions and opportunities.
Abstract: Maps depict natural and human-induced changes on earth at a fine resolution for large areas and over long periods of time. In addition, maps—especially historical maps—are often the only information source about the earth as surveyed using geodetic techniques. In order to preserve these unique documents, increasing numbers of digital map archives have been established, driven by advances in software and hardware technologies. Since the early 1980s, researchers from a variety of disciplines, including computer science and geography, have been working on computational methods for the extraction and recognition of geographic features from archived images of maps (digital map processing). The typical result from map processing is geographic information that can be used in spatial and spatiotemporal analyses in a Geographic Information System environment, which benefits numerous research fields in the spatial, social, environmental, and health sciences. However, map processing literature is spread across a broad range of disciplines in which maps are included as a special type of image. This article presents an overview of existing map processing techniques, with the goal of bringing together the past and current research efforts in this interdisciplinary field, to characterize the advances that have been made, and to identify future research directions and opportunities.
674 citations
TL;DR: The proposed demosaicing algorithm estimates missing pixels by interpolating in the direction with fewer color artifacts, and the aliasing problem is addressed by applying filterbank techniques to 2-D directional interpolation.
Abstract: A cost-effective digital camera uses a single-image sensor, applying alternating patterns of red, green, and blue color filters to each pixel location. A way to reconstruct a full three-color representation of color images by estimating the missing pixel components in each color plane is called a demosaicing algorithm. This paper presents three inherent problems often associated with demosaicing algorithms that incorporate two-dimensional (2-D) directional interpolation: misguidance color artifacts, interpolation color artifacts, and aliasing. The level of misguidance color artifacts present in two images can be compared using metric neighborhood modeling. The proposed demosaicing algorithm estimates missing pixels by interpolating in the direction with fewer color artifacts. The aliasing problem is addressed by applying filterbank techniques to 2-D directional interpolation. The interpolation artifacts are reduced using a nonlinear iterative procedure. Experimental results using digital images confirm the effectiveness of this approach.
462 citations
TL;DR: An overview of the image processing pipeline is presented, first from a signal processing perspective and later from an implementation perspective, along with the tradeoffs involved.
Abstract: Digital still color cameras (DSCs) have gained significant popularity in recent years, with projected sales in the order of 44 million units by the year 2005. Such an explosive demand calls for an understanding of the processing involved and the implementation issues, bearing in mind the otherwise difficult problems these cameras solve. This article presents an overview of the image processing pipeline, first from a signal processing perspective and later from an implementation perspective, along with the tradeoffs involved.
368 citations
TL;DR: The proposed fully automated vector technique can be easily implemented in either hardware or software; and incorporated in any existing microarray image analysis and gene expression tool.
Abstract: Vector processing operations use essential spectral and spatial information to remove noise and localize microarray spots. The proposed fully automated vector technique can be easily implemented in either hardware or software; and incorporated in any existing microarray image analysis and gene expression tool.
348 citations
References
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TL;DR: Within this framework, the same basic methods can be used to synthesize image data for color display monitors and printed materials, and to analyze image data into estimates of the spectral power distribution and surface spectral reflectances.
Abstract: I describe a method for performing the synthesis and analysis of digital color images. The method is based on two principles. First, image data are represented with respect to the separate physical factors, surface reflectance and the spectral power distribution of the ambient light, that give rise to the perceived color of an object. Second, the encoding is made efficient by using a basis expansion for the surface spectral reflectance and spectral power distribution of the ambient light that takes advantage of the high degree of correlation across the visible wavelengths normally found in such functions. Within this framework, the same basic methods can be used to synthesize image data for color display monitors and printed materials, and to analyze image data into estimates of the spectral power distribution and surface spectral reflectances. The method can be applied to a variety of tasks. Examples of applications include the color balancing of color images and the identification of material surface spectral reflectance when the lighting cannot be completely controlled.
287 citations
27 Aug 1992
TL;DR: A new method to generate halftone images which are visually optimized for the display device by recursively computing the change in perceived mean-squared error due to a change in the value of a binary pixel, and achieves a substantial reduction in computational complexity.
Abstract: In this work, we propose a new method to generate halftone images which are visually optimized for the display device. The algorithm searches for a binary array of pixel values that minimizes the difference between the perceived displayed continuous-tone image and the perceived displayed halftone image. The algorithm is based on the direct binary search (DBS) heuristic. Since the algorithm is iterative, it is computationally intensive. This limits the complexity of the visual model that can be used. It also impacts the choice of the metric used to measure distortion between two perceived images. In particular, we use a linear, shift- invariant model with a point spread function based on measurement of contrast sensitivity as a function of spatial frequency. The non-ideal spot shape rendered by the output devices can also have a major effect on the displayed halftone image. This source of non-ideality is explicitly accounted for in our model for the display device. By recursively computing the change in perceived mean-squared error due to a change in the value of a binary pixel, we achieve a substantial reduction in computational complexity. The effect of a trial change may be evaluated with only table lookups and a few additions.
280 citations
Book•
01 Jan 1983
TL;DR: In this article, the second edition of the Second Edition, the authors present a survey of color, light, and interaction in the field of band theory, including the following: Color, Light, and Interaction.
Abstract: Preface to the Second Edition.Preface to the First Edition. Acknowledgments for the Second Edition. Acknowledgments for the First Edition. LIGHT AND COLOR. Some Fundamentals: Color, Light, and Interactions. COLOR INVOLVING VIBRATIONS AND SIMPLE EXCITATIONS. Color Produced by Incandescence. Color Produced by Gas Excitations. Color Produced by Vibrations and Rotations. COLOR INVOLVING LIGAND FIELD EFFECTS. Color Caused by Transition Metals in a Ligand Field. COLOR INVOLVING MOLECULAR ORBITALS. Color in Organic Molecules. Charge Transfer Color. COLOR INVOLVING BAND THEORY. Color in Metals and Semiconductors. Color Centers. COLOR INVOLVING GEOMETRICAL AND PHYSICAL OPTICS. Dispersive Refraction and Polarization. Scattering and Nonlinear Effects. Interference and Diffraction. COLOR--RELATED TOPICS. Colorants of Many Types. Vision, Luminescence, Lasers, and Related Topics. Appendix A: Units, Chromaticity, and Color Order Systems. Appendix B: Incandescence Equations. Appendix C: Atoms and Simple Molecules. Appendix D: Crystal Fields, Ligand Fields, and Molecular Orbitals. Appendix E: Band Theory. Appendix F: Prism, Thin Film, and Layer Diffraction Grating. Appendix G: Recommendations for Additional Reading. Index.
274 citations
Book•
01 Dec 1994
TL;DR: In this article, the spectral properties of a blackbody radiation detector were investigated and the spectral selectivity of the detector was evaluated using the integral calculus of light and luminance, and some basic colour concepts were applied to the energy and illumination performance.
Abstract: Fundamental concepts of radiometry - electromagnetic radiation, radiation conventions, solid angle and wavelength notations, fundamental definitions, radiance and irradiance, connection with electromagnetic theory, polarization, photon flux, example problems fundamental concepts of photometry - light, photometric definitions, luminance and brightness, vision, disability glare, discomfort glare, illumination, example problems blackbody radiation - luminous efficacy of blackbody radiation, colour and distribution temperatures, Wien displacement law, emission into an imperfect vacuum, experimental approximation of a blackbody, sample problems source/receiver flux transfer calculations - geometry and definitions, configuration factor, net exchange or radiation optical properties of material - surface and interface optical properties, bulk medium optical properties, properties of place parallel plates, angular dependence, broadband angle properties, spectral dependence, broadband spectral properties, spectral selectivity, example problems the detection of radiation - basic concepts, classification of detectors, detector noise, signal modulation and radiation chopping, characterization of detector performance, flux conditioning prior to the detector, signal conditioning after the detector, detector calibration radiometry and photometry of optical systems - additional radiometric and photometric quantities and units, some basic colour concepts, application to the energy and illumination performance of Windows, appendix - correspondnece between finite elements and integral calculus.
260 citations
TL;DR: The principles that guided the founders of the CIE 1931 system for colorimetry are examined in this article, and the necessity for each of these principles in the modern world is examined critically to determine whether one might hold to the same principles if the system were being freshly formulated today.
Abstract: The principles that guided the founders of the CIE 1931 system for colorimetry are examined. The principles are applied to the Wright-Guild experimental determinations of the color mixture data to show in detail how and why each step in the development of the CIE 1931 system for colorimetry came about. These steps are examined in the light of 65 years advanced knowledge of colorimetry. The necessity for each of these principles in the modern world is examined critically to determine whether one might hold to the same principles if the system were being freshly formulated today. © 1997 John Wiley & Sons, Inc. Col Res Appl, 22, 11–23, 1997.
254 citations