Color Management System Research Articles

SpecialChem launches a breakthrough online colour management system

SpecialChem launches a breakthrough online colour management system

Application of a Linear-Light Color Management System to Transform Digital Imagery to Film

Accurately representing digitally generated imagery on print film has historically been difficult due to the differences between an inherently stable digital system and an inherently unstable photochemical system. There are many points in the color pipeline that are variable and if not properly identified and addressed, produce unpredictable results. By digitally representing color as device-independent linear-light values, functions can be created that define a particular output devices' response to those values and inverse functions then applied on output to compensate. In practice, all linear-light values cannot be represented by a cathode ray tube (CRT) or print film, so the output functions must be balanced so that the deficiencies of one device are compensated for by the other. In the print industry, this is called “proofing,” and while the output devices may differ in nature, the concept is valid and can be successfully applied to film output.

P-161: LED Illuminated Z-Cube Light Engine

A novel LED-based illumination optics and color management system, Z cube, has been proposed for improving the primary saturation, uniformity and contrast of LCoS projector engines. In this paper, the working concept of the light engine is described and the optical performance has been evaluated with the simulation using ray tracing program, which shows a good uniformity for projector application.

The New Challenge for Color Management in Digital Printing

Since eight industrial leading companies formed the International Color Consortium (ICC) in 1993, color management based on ICC profile has become the de-facto standard for color reproduction in digital printing. Today, ICC profile and color management are hot research topics. However, it will become more difficult to describe the role or benefits of color management for any specific user in the near future because Microsoft, one of the eight founder members of the ICC, quitted the consortium last year and started to develop the next generation color management system based on scRGB rather than Profile Connection Space (PCS) recommended by ICC. This is a new challenge for ICC to greater uptake of ICC color management in the digital printing industry. This paper aims to address this challenge and its impacts on color management in digital printing industry and ICC. It first analyzes the differences between the color management architectures based on PCS and scRGB used by Microsoft's New Generation Windows Color Architecture (NGWCA). It then discusses the new features of Microsoft's NGWCA. Finally, it discusses an opportunity of further R&D for the next generation color management solutions, and proposes some future research and development directions such as color profile format specification, color appearance modeling, gamut mapping methods, and profile verification to address the challenge in the next generation of color management.

Colour management: a workable solution.

Within clinical photography, colour reproduction has always been a contentious issue. With the development of new technologies, the variables affecting colour reproduction have changed and photographers have altered practices, moving away from the realm of film to digital photographic imaging systems. In order to standardize the output of digital clinical images, the author researched, and successfully implemented, the GretagMacbeth EYE-ONE Pro colour management system. This system, which is maintained on a monthly basis, has ensured a colour-consistent, reliable and efficient workflow throughout the digital clinical set-up.

カラーデバイスと画像・信号処理 VI 6. デバイス間をつなぐ画像処理 6.1 異機種間でのカラーマネージメント

カラーデバイスと画像・信号処理 VI 6. デバイス間をつなぐ画像処理 6.1 異機種間でのカラーマネージメント

Spectral Colorimetry Using LabPQR – An Interim Connection Space

A method of converting reflectance spectra to a convenient intermediate form introduced as LabPQR is used as an Interim Connection Space (ICS) within a spectral color management system. The LabPQR ICS makes use of a spectral encoding that explicitly incorporates colorimetry with additional dimensions that define spectral error corrections that allow an inverse transformation to approximate the original spectra. Consistent with a previously defined spectral color management transformation chain, the PQR dimensions of the ICS can be optimally formulated to suit any specific output device's spectral characteristics. Several example transformations are demonstrated using various output devices with spectral gamut visualizations. Observations are made, and from these observations, a possible method of performing spectral gamut mapping is proposed.

Masking model for accurate colorimetric characterization of LCD

Abstract— A color management system (CMS) such as ICC profile or sRGB space have been proposed for color transformation and reproduction of cross media. In such a CMS, accurate colorimetric characterization of a display device plays a critical role in achieving device‐independent color reproduction. In the case of a CRT, colorimetric characterization based on a GOG model is accurate enough for this purpose. However, there is no effective counterpart in liquid‐crystal displays (LCDs) since the characterization of an LCD has many difficulties, such as channel interaction and non‐constancy of channel chromaticity. In this paper, a new method of display characterization is proposed which is applicable to the assessment of color reproduction of LCDs. The proposed method characterizes an electro‐optical transfer function considering both channel interaction and non‐constancy of channel chromaticity. Experimental results show that the proposed method is very effective in the colorimetry of LCDs.

10.5: Ultra High Contrast Color Management System for Projection Displays

AbstractA high‐performance color management architecture is presented for use in 2‐ and 3‐panel LCoS projection display systems. Benefits of the proposed system include extremely high contrast at low f/−, excellent uniformity, adjustable color gamut, high reliability, and elimination of stress birefringence issues that have plagued previous color management systems for LCoS. We discuss the design and conceptual layouts of the new UltreX™ architecture and present experimental results for 2‐ and 3‐panel prototype systems.

Color management of liquid crystal display placed under light environment

AbstractWe studied the color management of liquid crystal displays (LCDs) placed in a light environment. In this paper, we first explained LCD problems related to color management and proposed an appropriate color management system when using an LCD. We also applied this system and examined the color management of an LCD placed in a light environment. Based on the proposed method, we showed that favorable color reproduction properties are obtained for LCDs in a light environment as well as a dark room. We reevaluated the LCD from the perspective of compatibility with the ICC profile. LCDs have superior γ and brightness characteristics, but have the problem of the chromaticity coordinates of reference white and the primary colors changing in response to the input signal value. This indicated a problem related to the contrast ratio of the LCD and showed that the changes in the chromaticity coordinates of the primary colors can be adequately described if the leakage light is considered. Based on this, we proposed a suitable device profile and color management system for LCDs and demonstrated excellent color reproduction in a dark room. Next, we examined the LCD placed in a light environment. We showed that if the LCD is designed so that the surface reflected light produced in a light environment is handled in the same manner as leakage light and suitable surface reflected light is produced, fluctuations in the chromaticity coordinates of reference white could be avoided. We placed a prototype of this type of LCD in an actual light environment and applied and evaluated the proposed color management system. This result showed that a low color reproduction error could be maintained even when a dark image was displayed on an LCD placed in a light environment and confirmed a subjective improvement in the image quality. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 86(7): 1–14, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.10074

The Influence of Paper Properties on Color Reproduction and Color Management

The characterization of the transfer function of a printing device is a complex procedure involving not only the device itself but also the paper and its properties. The work reported here is an ongoing development of building a library of characterization procedures. These procedures can be applied to printing situations with different combinations of printing engines and paper grades. An example of a building block is color separation with respect to halftoning techniques and available inks or toners. Another is the characterization of the physical properties of the paper substrate. The most common characterization procedure is through the ICC-profile. Device ICC-profiles contain the data needed for a color management system (CMS) to do color separation and the color mapping. In this study special emphasis is put on the influence of the paper properties and on how they affect the profile. Gloss, surface roughness, whiteness and light scattering are all measurable paper properties that certainly will affect the color reproduction. Ink and paper interaction and especially ink penetration is also a phenomena that affect the color reproduction and thus the ICC profile.

51.2: Skew‐Ray Compensated Retarder‐Stack Filters for LCOS Projection

AbstractCompact liquid crystal on silicon (LCOS) based projection engines have been demonstrated that use retarder stack filters with polarizing beamsplitters as the basis of a color management system. A new class of retarder stack filter compensates for the geometrical rotation characteristic of polarizing beamsplitters, further improving attainable system performance.

AN ON-LINE COLOR MANAGEMENT SYSTEM BASED ON A NON-LINEAR PREDICTIVE APPROACH

Color is an important variable in many processes since it defines the final appearance of the product. The color management system must not only consider the non-linearities of the process but also the operational constraints. This work proposes a Predictive Controller Approach, based on a sequential linear programming algorithm, for an on-line color recipe formulation and correction. Experiments with three colorants are presented, demonstrating the performance of the proposed algorithm.

An investigation of the use of digital colour matching for the toning of papers using ink-jet printing

Summary The author investigated the possibility of defining colour digitally, based on the tristimulus values of an established target, and obtaining accurate reproduction through ink-jet printing. The effectiveness of the process was assessed using a poster with a missing black-coloured area. The missing colour was set as the target to be digitally reproduced. CIE L*a*b* values and spectral reflectance curves of printed specimens were compared to those of the target in a viewing booth under illuminant D65. Accurate colour reproduction was found to be possible and the use of this method for toning in fills on paper objects could save time when compared to conventional methods, thus being cost-effective. The merits of adopting a reliable Colour Management System are outlined and the steps involved in achieving this novel approach towards the toning of paper are described in detail.

An Accurate Characterization of CRT Monitor (I) Verifications of Past Studies and Clarifications of Gamma

CRT monitors are widely used to view images on the Internet. The color images on the computer graphic display can be printed out or displayed on other monitors through the Internet, and color matching between the original and the reproduction is very important. The color management systems (CMSs) are useful for the color matching. CMSs utilize device profiles, in which color characteristic information is stored, and these profiles are generated by device characterization. Thus, an accurate characterization of the monitor is essential for better color matching. CRT monitor characteristics can be described by the tone reproduction curves (TRCs) of each channel, and color additive matrix. In this paper, these characteristics were investigated from a physical point of view. Various kinds of flare and the interdependence among the channels were also investigated and verified. The definition of the term “gamma” is clarified, which is very often used to describe the TRC. Various definitions are compared and a new definition of S-γ is proposed.

An Accurate Characterization of CRT Monitor (II) Proposal for an Extension to CIE Method and Its Verification

According to the ICC specification that is widely used for storing colorimetric characteristics of imaging devices for the current color management systems (CMSs), CRT monitor characteristics can be described by the tone reproduction curves (TRCs) of the red, green and blue channels and a transformation matrix from linearized RGB values to tristimulus values. This idea is based on CIE Technical Report 122#x2013;1996: #x201C;The Relationship between Digital and Colorimetric Data for Computer-Controlled CRT Displays,#x201D; which resulted from the research by Berns et al. This method produces very accurate results under normal conditions. However, users often change the settings of contrast or brightness knobs to a different position from the factory default adjustments. For some of these cases, the characterization method described in the CIE 122 does not produce accurate results. In this paper, we propose an extension to the CIE method for such cases. We investigated the effect of user controls on CRT monitor characteristics at various settings, and verified that our method produced accurate results under any conditions.

Interpolation errors on gray gradations caused by the three-dimensional lookup table method

Three-dimensional table interpolation techniques are now widely used in color management systems. These techniques are practical because complicated color conversions such as gamma conversion, matrix masking, under color removal, or gamut mapping can be executed at once by use of a three-dimensional lookup table (3D LUT). However, in some cases, the resultant interpolated reproduction of gradation has visible artifacts that degrade neutral and color gradations. Several research works concerning interpolation accuracy have been published. However, those articles have focused on an average color difference derived from experiments based on very few types of color conversions with no theoretical explanation. This paper describes a theoretical evaluation of errors and reproduced gradation curves using three-dimensional interpolation for several nonlinear color conversions. Two types of errors; conventional error and ripple error that is difference between piece-wise linear approximation and interpolated curves are defined, and gray gradation is used for an input image. The errors with a tetrahedral interpolation technique are also examined. Several nonlinear color conversions are tested and significant ripples have been found in case of the matrix-gamma with negative coefficients and minimum (MIN) function. The error goes down with decreasing of the distance between the lattice points (D), however, the decreasing rate is quite different. From these analyses we can get useful information about optimal 3D LUT sizes and which conversions are suitable for three-dimensional interpolation.

SOIL LANDSCAPE MODELS AT DIFFERENT SCALES PORTRAYED IN VIRTUAL REALITY MODELING LANGUAGE

Most state-of-the-art manipulations and visualizations of soil data use geographic information systems to portray soil landscapes in two dimensions (2-D). Nevertheless, soil attributes are distributed continuously in three dimensions (3-D) across landscapes. The objective of this study was to investigate the use of Virtual Reality Modeling Language (VRML), a 3-D graphics language suitable for stand-alone or browser-based interactive viewing, to create 3-D soil landscape models at different scales. Four different locations in southern Wisconsin were selected to represent pedon, catena, catchment, and soil region scales. Soil data, including texture, cone index, and depth of soil layers, were used in conjunction with topographic attributes to create 3-D soil landscape models. Spatial modeling techniques comprised 2-D and 3-D ordinary kriging. We used Environmental Visualization Software (EVS) to export the geometry of 3-D objects, which were enhanced to include: (i) viewpoints, (ii) Munsell colors, (iii) texture maps, (iv) 3-D cross-section animation, (v) animations such as zooming and rotation, and (vi) primitive shapes to highlight areas of interest. Virtual reality modeling language is capable of describing and visualizing extremely complex shapes, such as complex soil layers or terrain. Visualization of Munsell soil colors was difficult to implement because there is no hardware or software independent color-management system available in VRML. Animation techniques were valuable to high-light specific characteristics of each model. The accessibility of interactive VRML models via the World Wide Web and the portability of these models across platforms facilitate the entry of soil science into the virtual world of cyberspace.

A critical review of spectral models applied to binary color printing

A critical review of binary color printing models is presented. The goal is to provide an understanding of the application of color printer models as a component for device profiles within a color management system. A short description of a modern color management system is pre- sented, followed by a brief explanation of the halftoning process. This leads into the discussion of the individual models, which takes an historical approach. The discussion starts with early models proposed in the 1930s by Murray, followed by Neugebauer, Yule and Nielsen, and other much more recent model forms. To aid in gathering the appro- priate data for printer modeling, experimental techniques are then discussed, followed by an explanation of the model optimization methods needed for parameter fitting. The re- view concludes with procedures for model evaluation and a presentation of the results from an application of the models to a sample dataset for an electrophotographic printer.

Color Management Requirements in Contract Proofing

Generally, one can say that ease of use requirements for color management are driven by DTP and home users, whereas since the early days of color management accuracy requirements have been driven by the contract proofing market. Translating colors from one color model to another, matching to targets, dealing with out of gamut colors, etc., were and are issues that drive proofing manufacturers to continuously improve their color management software.As faster computer hardware and automated measuring devices become available, and as more companies develop color management systems, improvements in color management are realized.But, the customer requirements change over the years. Items like Pantone colors, paper color, gloss influence, remote proofing, match transferability, etc., change the requirements from the customer.Finally, most customers still think in CMYK and have problems understanding an L*a*b process, which is commonly used in today's color management systems.For developers of color management this means a continuous challenge to update their software and utilize the new possibilities that improved hardware delivers. This paper gives an overview of color requirements for contract proofing, how these requirements are met with proofing hardware, and which color management software challenges were and still are to be dealt with to provide accurate digital contract proofs.