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.
Citations
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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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16 Sep 1996
TL;DR: An algorithm for image browsing systems that embeds a color halftone into another color Halftone of a higher bit depth, as well as embedding a grayscale or binary halftones into a gragescale or color halfts, and several methods for color palette organization, or binary index assignment, are presented.
Abstract: We present an algorithm for image browsing systems that embeds a color halftone into another color halftone of a higher bit depth, as well as embedding a grayscale or binary halftone into a grayscale or color halftone. The benefit of this algorithm is that a low bit-depth halftone can be directly obtained from a higher bit-depth halftone for printing of progressive transmission simply by masking one or more bits off of the color halftone. The embedding can be done in any bit of the output depending on the organization of the image palettes, although the most significant or the least significant bits are most convenient. The embedding algorithm that we describe requires the use of scalar quantizers and ordered vector quantizers. We present several methods for color palette organization, or binary index assignment, to be used in conjunction with the embedded color error diffusion algorithm.
17 citations
TL;DR: A cost-effective variable-separable formulation based on the concept of Golub and Pereyra (1973) is adopted to reduce the nonlinear LS problem to be a small-scale non linear LS problem.
Abstract: Separating a color signal into illumination and surface reflectance components is a fundamental issue in color reproduction and constancy. This can be carried out by minimizing the error in the least squares (LS) fit of the product of the illumination and the surface spectral reflectance to the actual color signal. When taking in account the physical realizability constraints on the surface reflectance and illumination, the feasible solutions to the nonlinear LS problem should satisfy a number of linear inequalities. Four distinct novel optimization algorithms are presented to employ these constraints to minimize the nonlinear LS fitting error. The first approach, which is based on Ritter's superlinear convergent method (Luengerger, 1980), provides a computationally superior algorithm to find the minimum solution to the nonlinear LS error problem subject to linear inequality constraints. Unfortunately, this gradient-like algorithm may sometimes be trapped at a local minimum or become unstable when the parameters involved in the algorithm are not tuned properly. The remaining three methods are based on the stable and promising global minimizer called simulated annealing. The annealing algorithm can always find the global minimum solution with probability one, but its convergence is slow. To tackle this, a cost-effective variable-separable formulation based on the concept of Golub and Pereyra (1973) is adopted to reduce the nonlinear LS problem to be a small-scale nonlinear LS problem. The computational efficiency can be further improved when the original Boltzman generating distribution of the classical annealing is replaced by the Cauchy distribution. >
17 citations
18 Jun 1993
TL;DR: This work presents some research into the problem of visualizing the 3-D data used in the process of calibrating a printer, and presents some visualizations that include the rendering of3-D gamuts, and vector spaces, and the ability to move around these 3- D spaces to examine details of the 3,D data set.
Abstract: Colorimetric calibration is the process of producing colorimetrically correct data from a device. For the case of a scanner this would involve the process of converting scanner signals into signals which are related in a known way to some colorimetric standard. In the case of a printer, the process is reversed, the task at hand is to determine the printer signals necessary to produce a desired colorimetric signal. A common way of representing colors is by a three dimensional vector. This may be red, green, blue signals, CIE L*, a*, and b* values, or any one of a number of other coordinate systems. Colorimetric calibration can be viewed as the transformation of data in one 3-D space to data in another 3-D space. I present some research into the problem of visualizing the 3-D data used in the process of calibrating a printer. The visualizations are rendered onto a 2-D display, and include the rendering of 3-D gamuts, and vector spaces, and the ability to move around these 3-D spaces to examine details of the 3-D data set.
15 citations
01 Jun 1990
TL;DR: In this article, the color imaging system in terms of vector space notation is described, including the effects of the scanning filters and the response of the eye as defined by the CIE color matching functions.
Abstract: This paper describes the color imaging system in terms of vector space notation. This includes the effects of the scanning filters and the response of the eye as defined by the CIE color matching functions. This formulation allows many image processing techniques to be generalized to include more accurate models. The problem ofimage restoration is used as an example for the vector space approach. The problem is presented in hierarchical steps. Color scanning and effect of the human observer is presented first. The problem is extended to spatial representation and spatial processing. Finally, the effects of image reproduction are considered. The assumptions at each step of the modelling process are made explicit and simplifications are noted. The choice of defining the most appropriate optimization function is considered with respect to mathematical tractability as well as subjective accuracy.© (1990) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
14 citations
27 Apr 1995
TL;DR: This paper reviews the color image processing techniques used in the printing industry for the color space transformation as the color mixing models, multiple regression, 3D lookup table (LUT) with interpolation, neural network, and fuzzy logic.
Abstract: This paper reviews the color image processing techniques used in the printing industry for the color space transformation. Generally, the techniques can be classified as the color mixing models, multiple regression, 3D lookup table (LUT) with interpolation, neural network, and fuzzy logic. The following techniques are briefly discussed. (1) Color mixing models such as the Neugebauer equations, Yule-Nielsen model, Clapper-Yule model, Beer-Bouguer law, and Kubelka-Munk theory. (2) Multiple regression. (3) 3D LUT with four geometric interpolations - trilinear, prism, pyramid, and tetrahedral. (4) Artificial neural networks of the multilayer feed-forward and cascade correlation nets. (5) Fuzzy logic. These techniques are compared, whenever possible, with respect to the accuracy, memory requirement, speed, and computational cost.© (1995) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
13 citations