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: In this paper, two color-formulation strategies, tristimulus colorimetric and least-squares curve fitting, are discussed: the trISTIMULUS matching strategy (ΔED65)2 + ( ΔEA)2+ ( ΔEWWF)2 → min, and the least squares curve fitting strategy ( Σjw2j[ΔR(λj)]2→ min).
Abstract: The article discusses two types of colour-formulation strategies: the tristimulus colorimetric strategy (ΔX,ΔY,ΔZ) → (0,0,0) and the least-squares curve fitting Σjw2j[ΔR(λj)]2 → min. Then a new matching strategy (ΔED65)2 + (ΔEA)2 + (ΔEWWF)2 → min is stated, which tries to combine the advantages of the first two strategies: more “balanced” colour differences for several different illuminants (the case of curve fitting) and small colour differences for the illuminant involved in the matching process (the case of tristimulus matching). An algorithm following this new general strategy is constructed using the case of single-constant Kubelka-Munk theory as an example. Results of a few numerical experiments are included for illustration.
31 citations
TL;DR: A visual colorimeter was designed to implement a new model for the determination of color-matching functions developed in the Munsell Color Science Laboratory, and results from an individual observer correlate well with data collected on the National Research Council of Canada's Trichromator.
Abstract: A visual colorimeter was designed to implement a new model for the determination of color-matching functions developed in the Munsell Color Science Laboratory. An instrument utilizing laser primaries was originally developed. The instrument was later improved to incorporate CRT primaries and seven interference filters to make matches to simulated daylight in a 2° bipartite field. The system was designed to minimize the strain on observers. Color-matching functions of naive observers can be measured in approximately 30 minutes. Results from an individual observer correlate well with data collected on the National Research Council of Canada's Trichromator. Part II of this article gives the color-matching functions results for 18 observers and 20 repetitions by a single observer.
31 citations
TL;DR: A theory of color vision is presented which attempts to account for the physics, physiology, and psychology of the color-vision process, and a new color diagram is developed, based upon the simplest version of the theory.
Abstract: A theory of color vision is presented which attempts to account for the physics, physiology, and psychology of the color-vision process Three types of photopigments are assumed to be distributed among five types of cones It is suggested that color signals are of an opponent-colors variety from retina to lateral geniculate body, then coded in terms of the four psychologically unique colors from the lateral geniculate to the visual cortex The theory is quantitative and provides an explanation of protanopia, deuteranopia, and tritanopia A new color diagram is developed, based upon the simplest version of the theory Suggestions are made concerning how this diagram might be modified to produce a more uniform color space, and the meaning of such modifications is discussed in terms of the theory
30 citations
Proceedings Article•
01 Jan 1994
28 citations
27 Apr 1995
TL;DR: In this article, a dot-on-dot halftone screen model is described for a given input CMYK signal, the model predicts the resulting spectral reflectance of the printed patch.
Abstract: A printer model is described for dot-on-dot halftone screens. For a given input CMYK signal, the model predicts the resulting spectral reflectance of the printed patch. The model is derived in two steps. First, the C, M, Y, K dot growth functions are determined which relate the input digital value to the actual dot area coverages of the colorants. Next, the reflectance of a patch is predicted as a weighted combination of the reflectances of the four solid C, M, Y, K patches and their various overlays. This approach is analogous to the Neugebauer model, with the random mixing equations being replaced by dot-on-dot mixing equations. A Yule-Neilsen correction factor is incorporated to account for light scattering within the paper. The dot area functions and Yule-Neilsen parameter are chosen to optimize the fit to a set of training data. The model is also extended to a cellular framework, requiring additional measurements. The model is tested with a four color xerographic printer employing a line-on-line halftone screen. CIE L*a*b* errors are obtained between measurements and model predictions. The Yule-Neilsen factor significantly decreases the model error. Accuracy is also increased with the use of a cellular framework.© (1995) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
28 citations