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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09 May 1994
TL;DR: In GamOpt, a tool for visualization and optimization of color gamuts, algorithms are implemented to estimate the transfer function between input parameters such as pigment concentrations and the L*a*b* coordinates they generate in a palette, and generate the values of the input parameters required to produce an optimized gamut.
Abstract: This paper describes GamOpt, a tool for visualization and optimization of color gamuts. In GamOpt, a gamut may be viewed on a computer display, manipulated interactively, or optimized based on constraints. A gamut may be visualized for geometric and color intuition. Gamut points specified in L*a*b* color space may be plotted in projected 3-space. The display may be interactively manipulated to obtain insight about distribution patterns. The gamut may also be color coded in a variety of ways. Multiple gamuts may be visualized at the same time using color or geometrical cues to differentiate them. Two optimization schemes are provided, interactive and analytical. In interactive optimization, a gamut may be modified either interactively or by arbitrary user-defined functions, changing the shape and orientation of the gamut. The analytic optimization approach is based on defining numerical metrics for the goodness of gamuts. The gamut is transformed analytically to optimize these metrics. Using algebraic and neural techniques, we have implemented algorithms to estimate the transfer function between input parameters such as pigment concentrations and the L*a*b* coordinates they generate in a palette. We can then generate the values of the input parameters required to produce an optimized gamut.
9 citations
23 Oct 1995
TL;DR: This paper presents a method of losslessly compressing these palettized images, which treats each color independently, and provides substantial compression improvement over other known methods for most images.
Abstract: Palettized or indexed color images are the dominant type of image used on the "information super highway." In spite of this, most image compression algorithms are designed for continuous-tone images. This paper presents a method of losslessly compressing these palettized images, which treats each color independently. This color-plane method provides substantial compression improvement over other known methods for most images.
8 citations
01 Jul 1995
TL;DR: The current state of the art and future trends in camera and display technology are described, including the use of these devices in a multimedia environment, as applied to digital television systems.
Abstract: We first discuss the position of cameras and displays in digital television systems. It is difficult to realize these devices in digital form so cameras and displays will remain analog for some time, even after television signal processing is implemented digitally. Nevertheless, the importance of camera and display in television systems will not diminish. These devices will always be key elements in the human interface. Second, we describe the current state of the art and future trends in camera and display technology. In addition to providing an overview of the charge coupled device (CCD), we discuss the digital technologies used in a CCD camera. We also provide an overview of currently available displays-CRT's, flat panel displays, projection displays, and head-mounted displays (HMD's)-and discuss future possible lines of research. Finally, we discuss camera and display technology as applied to digital television systems, including the use of these devices in a multimedia environment. >
8 citations
Proceedings Article•
01 Jan 1996
TL;DR: In this article, the effects of optical and physical dot gain on the size of the color gamut have been investigated, and it is shown that a large dot gain, which is commonly regarded as an unwanted distortion, expands the color range quite considerably.
Abstract: Color mixing by a halftoning process, as used for color reproduction in graphic arts and most forms of digital hardcopy, is neither additive nor subtractive. Halftone color reproduction with a given set of primary colors is heavily influenced not only by the colorimetric properties of the full-tone primaries, but also by effects such as optical and physical dot gain and the halftone geometry. We demonstrate that such effects not only distort the transfer characteristics of the process, but also have an impact on the size of the color gamut. In particular, a large dot gain, which is commonly regarded as an unwanted distortion, expands the color gamut quite considerably. We also present an image processing model that can describe and quantify the effects of physical and optical dot gain on different media and with different halftoning methods.
7 citations