International Color Consortium Profile Research Articles

Domain and range of the CIECAM16 forward transformation.

The domain and range of the CIECAM16 forward transformation was numerically determined and visualized for CIE standard illuminants, using a linear programming approach that provides the gamuts and colour solids for optimum colours. The effect of the surround, adapting luminance, and luminance of the background on the range of the CIECAM16 forward transformation were individually analyzed, showing that their ranges increased when the surround changed from dark to dim or average, the adapting luminance increased, or the luminance of the background decreased. The proposed methodology for the determination and visualization of the domain and range of the CIECAM16 forward transformation can be used for any illuminant, as well as for CIECAM02, CAM16, CAM02-UCS and CAM16-UCS. The findings of this paper not only solve the long-term unresolved domain and range problems of the CIE colour appearance models, but also find applications in cross-media colour reproduction. Furthermore, it was also found that some non-CIE colours are inside the International Color Consortium Profile Connection Space (ICC PCS), and some CIE colours are not included in that space.

Study of color reproduction in pigment digital printing

In pigment ink digital printing, the color difference between the original and the printed product can be visible due to the varied color gamut of devices and the impact of fabric characteristics on the color-presenting effect. To improve the color reproduction accuracy of digital printing, two methods, the full-process optimized (FPO) method and the neural network aided original adjustment (NNAOA) method, were proposed to reduce printing color difference during the color-transferring process. The FPO method, based on accounting for the fabric type and the characteristics of the printing machine, was proposed by optimizing the printing parameter settings in the color management process. Here, the optimal single-channel ink limit was determined and dot gain was compensated using the inverse function correction method, and then the International Color Consortium profile was generated. After using the FPO method, the color difference between the printed sample and the original was reduced from 20.8 to 5.254 compared with performing the original color management. To reduce the reliance on personal experience in color adjustment, the NNAOA method was proposed and implemented for 20 color patches with the largest color differences in the FPO method, allowing the color of the originals to be adjusted with the establishment of the general regression neural network model. This method predicted the input CMYK values of the original using measured L*a*b* values for the printed sample. The results showed that the color difference of the 20 color patches was reduced from 8.54 to 6.60. Consequently, both methods offered distinguishable improvements in the color reproduction effect.

New software for comparing the color gamuts generated by printing technologies

In the color industry, it is vital to know the color gamut of a given device. Several tools for visualizing and comparing color gamuts are available but they each have some drawbacks. Therefore, the aim of this work was to develop and validate new software for comparing the color gamuts generated by printing devices; we also developed an automated color measurement system. The software simultaneously represents the gamuts in the 3D CIELAB space. It also calculates the Gamut Comparison Index and the volume using two algorithms (Convex Hull and Alpha Shapes). To evaluate the performance of our software, we first compared the results it obtained for the color gamuts with those from other comparison methods such as representation in the CIE 1931 chromaticity diagram or other color spaces. Next, we used Interactive Color Correction in 3 Dimensions (ICC3D) software to compare the gamut representations and volumes. Our software allowed us to identify differences between color gamuts that were not discriminated by other methods. This new software will enable the study and comparison of gamuts generated by different printing technologies and using different printing substrates, International Color Consortium profiles, inks, and light sources, thereby helping to achieve high quality color images.

DICOM Format and Protocol Standardization-A Core Requirement for Digital Pathology Success.

As the use of digital techniques in toxicologic pathology expands, challenges of scalability and interoperability come to the fore. Proprietary formats and closed single-vendor platforms prevail but depend on the availability and maintenance of multiformat conversion libraries. Expedient for small deployments, this is not sustainable at an industrial scale. Primarily known as a standard for radiology, the Digital Imaging and Communications in Medicine (DICOM) standard has been evolving to support other specialties since its inception, to become the single ubiquitous standard throughout medical imaging. The adoption of DICOM for whole slide imaging (WSI) has been sluggish. Prospects for widespread commercially viable clinical use of digital pathology change the incentives. Connectathons using DICOM have demonstrated its feasibility for WSI and virtual microscopy. Adoption of DICOM for digital and computational pathology will allow the reuse of enterprise-wide infrastructure for storage, security, and business continuity. The DICOM embedded metadata allows detached files to remain useful. Bright-field and multichannel fluorescence, Z-stacks, cytology, and sparse and fully tiled encoding are supported. External terminologies and standard compression schemes are supported. Color consistency is defined using International Color Consortium profiles. The DICOM files can be dual personality Tagged Image File Format (TIFF) for legacy support. Annotations for computational pathology results can be encoded.

Design and Optimization of Color Lookup Tables on a Simplex Topology

An important computational problem in color imaging is the design of color transforms that map color between devices or from a device-dependent space (e.g., RGB/CMYK) to a device-independent space (e.g., CIELAB) and vice versa. Real-time processing constraints entail that such nonlinear color transforms be implemented using multidimensional lookup tables (LUTs). Furthermore, relatively sparse LUTs (with efficient interpolation) are employed in practice because of storage and memory constraints. This paper presents a principled design methodology rooted in constrained convex optimization to design color LUTs on a simplex topology. The use of n simplexes, i.e., simplexes in n dimensions, as opposed to traditional lattices, recently has been of great interest in color LUT design for simplex topologies that allow both more analytically tractable formulations and greater efficiency in the LUT. In this framework of n-simplex interpolation, our central contribution is to develop an elegant iterative algorithm that jointly optimizes the placement of nodes of the color LUT and the output values at those nodes to minimize interpolation error in an expected sense. This is in contrast to existing work, which exclusively designs either node locations or the output values. We also develop new analytical results for the problem of node location optimization, which reduces to constrained optimization of a large but sparse interpolation matrix in our framework. We evaluate our n -simplex color LUTs against the state-of-the-art lattice (e.g., International Color Consortium profiles) and simplex-based techniques for approximating two representative multidimensional color transforms that characterize a CMYK xerographic printer and an RGB scanner, respectively. The results show that color LUTs designed on simplexes offer very significant benefits over traditional lattice-based alternatives in improving color transform accuracy even with a much smaller number of nodes.

Comparing image quality of print-on-demand books and photobooks from web-based vendors

Because of the emergence of e-commerce and developments in print engines designed for economical output of very short runs, there are increased business opportunities and consumer options for print-on-demand books and photobooks. The current state of these printing modes allows for direct uploading of book files via the web, printing on nonoffset printers, and distributing by standard parcel or mail delivery services. The goal of this research is to assess the image quality of print-on-demand books and photobooks produced by various Web-based vendors and to identify correlations between psychophysical results and objective metrics. Six vendors were identified for one-off (single-copy) print-on-demand books, and seven vendors were identified for photobooks. Participants rank ordered overall quality of a subset of individual pages from each book, where the pages included text, photographs, or a combination of the two. Observers also reported overall quality ratings and price estimates for the bound books. Objective metrics of color gamut, color accuracy, accuracy of International Color Consortium profile usage, eye-weighted root mean square L*, and cascaded modulation transfer acutance were obtained and compared to the observer responses. We introduce some new methods for normalizing data as well as for strengthening the statistical significance of the results. Our approach includes the use of latent mixed-effect models. We found statistically significant correlation with overall image quality and some of the spatial metrics, but correlations between psychophysical results and other objective metrics were weak or nonexistent. Strong correlation was found between psychophysical results of overall quality assessment and estimated price associated with quality. The photobook set of vendors reached higher image-quality ratings than the set of print-on-demand vendors. However, the photobook set had higher image-quality variability.

Scanner Characterization for Color Measurement of EP Printed Output

Typical automated print quality assessment tools use desktop scanners to analyze printed output. Unfortunately, due to the noncolorimetric properties of scanners, results can vary significantly depending upon the scanner used. This paper describes an investigation into using ICC (International Color Consortium) profiling as a tool to characterize the color response of a given scanner. The goal of this work is to create a scanner profile that can accurately measure the color of EP (electophotographic) printed output through the manipulation of targets, post processing refinement techniques, and the minimization of the effects of scanner non-uniformities. Targets with known color characteristics were created and scanned. Using open source software, ICC profiles were created from the scans to characterize a scanner's response to the colors in the targets. Through experimentation, it was determined that the maximum error of the profile can be minimized through post processing refinement. The main contributors to the average error were scanner nonuniformities and target characteristics, including uniformity, type, layout, and gamut. The results show that it is possible to, on average, characterize the output of a single EP printer to within 2 ΔE76 and the output of several EP printers to within 3 ΔE76. This is a quality level good enough to suggest that ICC profiling can be a fast, cost-effective solution toward obtaining reasonable color consistency across scanners, as well as a possible low-cost alternative to a spectrophotometer for specific applications.

Color Correction for Multiple Light Sources Using Profile Correction System

In this article the authors propose a color correction system for images illuminated by multiple light sources. The proposed system can generate an illumination-invariant image under various light sources. Such illumination-invariant image acquisition becomes possible by adopting a user-defined profile connection space (UD-PCS) that generates custom profiles, which can be used to eliminate the effect of directional light sources. The proposed algorithm consists of the following steps: (i) input image capture with minimum of two light sources and reference Qpcard, (ii) estimation of color correction matrix and tone reproductive curves, (iii) modifying International Color Consortium profile tags to generate UD-PCS, and (iv) color mixture map extraction for fusion of input source images. Experiments were carried out on several test images with different light sources in order to prove the utility of the proposed algorithm.

Learning custom color transformations with adaptive neighborhoods

Custom color transformations for images or video can be learned from a small set of sample color pairs by estimating a look-up table (LUT) to describe the enhancement and storing the LUT in an International Color Consortium profile, which is a standard tool for color management. Estimating an accurate LUT from a small set of sample color pairs is challenging. Local linear and ridge regression are tested on six definitions of neighborhoods for twenty color enhancements and twenty-five color images. Excellent results were obtained with local ridge regression over proposed enclosing neighborhoods, including a variant of Sibson's natural neighbors. The evaluation of the different estimation methods for this task compared the fidelity of the learned color enhancement to the original sample color pairs and the presence of objectionable artifacts in enhanced images. These metrics show that enclosing neighborhoods are promising adaptive neighborhood definitions for local classification and regression.

Multispectral omnidirectional vision sensor: design, calibration, and utilization

The 3-D reconstruction of an environment with high accuracy and real textures represents an important challenge for applications related to multimedia and cinematography. The complete development, from electronic design to algorithmic restitution of the environment, of a multispectral omnidirectional stereoscopic sensor that tackles this problem is presented. Although panoramic sensors exist, the vision system presented here has four channels of acquisition coupled to a projector of structured light emitting in the infrared. This original process separates the acquisition of color images from 3-D reconstruction. The panoramic color images are corrected using the International Color Consortium profile applied to images coming from the two cameras. The reconstruction of the environment uses only the information available in the infrared channel. An active calibration technique is also presented. Experimental results demonstrate the feasibility of this new class of multispectral omnidirectional sensors.

Methodology for Evaluating the Quality of ICC Profiles–Scanner, Monitor, and Printer

The concepts and technology for an open loop color management system such as that specified by the International Color Consortium (ICC) have been around for a number of years. The adoption of this workflow by the graphic arts industry has been slow. A major contribution to the lack of popularity is that the quality part of the ICC workflow is unregulated and the average user is unable to independently assess the quality of profiles and profile making software. This paper describes a number of test methods that can be used to evaluate the colorimetric accuracy of ICC scanner, monitor, and printer profiles. ICC profiles are being used in a number of color proofing scenarios. In order to understand the color reproduction abilities of such proofing systems it is necessary to quantify the accuracy of the underlying ICC profiles used in the workflow. A quality metric can be useful to provide feedback on how well a device has been characterized and therefore provide limits on the ability of a color managed system. Further, a universally defined merit figure will allow the comparison of results across manufacturers, allowing the user to make informed choices appropriate for their workflow. If we are able to establish a benchmarking procedure akin to the miles per gallon fuel consumption quoted for motor vehicles this provides a universal quality metric that can help raise the quality of profiling software, assist user choice, and ultimately lead to the greater acceptance of ICC color management in graphic arts and the printing industry. The quality of input profiles is described in terms of a AE calculation. Input profiles from ten different profiling packages were evaluated. Profiles were made for a flatbed scanner using Agfa, Fuji, and Kodak IT8.7/2 targets. The average AE for input profiles is shown to be in the range of ΔE 0.60-2.46. A procedure is described for evaluating the quality of monitor profiles in terms of measured gamma, white point and the color reproduction of 24 specially chosen colors. Eleven monitor systems were evaluated. Monitor profiles were made for an Apple Cinema HD LCD display and measurements were made to verify the accuracy of these profiles using a telespectroradiometer. It is shown that commercial products were able to reproduce 24 patches of a color checker on a monitor with an average AE of 2.92-5.81. A printer profile metric is also described. This research describes three possible metrics for a printer profile-accuracy of the B2A 1 tag (PCS to Device), A2B1 tag (Device to PCS), and a round trip test. Data are presented to show that the average accuracy of the output profile colorimetric intent (average of B2A1 and A2B1) for an Epson ink jet printer can be between AE 1.72-3.49. The accuracy of the printer profile is useful when considering the use of an ink jet printer in color management proofing workflows. This research proposes a ΔE metric system that can be used to evaluate the quality of commercially created ICC input, display, and output profiles. The data presented here are fundamentally a methodology that can be used to estimate the colorimetric accuracy of profiles. The use of commercial profiling products is only to illustrate how the metrics may be determined in practice. The data, however, do show useful information about the state of color management products today and this analysis can be used to track the improvements and evolution in ICC profiling software.

Color Figures in BJ: RGB versus CMYK

Biophysical Journal has always striven to produce the best possible journal, and we have used the latest technology available to help us achieve that goal. In recent years, we have made changes that improved our service to authors and readers by implementing an online submission system. This has offered the convenience of uploading and previewing submission materials, and reduced our time from submission to print considerably. More recently, we have begun placing accepted papers online in our BioFAST module, so that papers may be accessed before they are published in print.

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.

Generation of an ICC Profile from a Proprietary Style File

In color imaging technologies one of the major parts of the scanning procedure is processing the raw RGB scanner data to make it suitable for printing on a given CMYK output device. The processing typically involves applying a number of technical and aesthetic, iteratively developed edits. These edits are stored in a proprietary file format, i.e. a type of vendor-specific macro file. There has been a recent shift from this closed loop type of color control to the open system of color management such as that specified by the International Color Consortium (ICC). ICC color managed workflows can only use a universally agreed file called a profile, and not proprietary user edit files. It may have taken a long time to perfect the proprietary edits and users will not want to lose them when they migrate to the new ICC workflows. This article describes a process that allows users to convert color edit information from a vendor-specific proprietary edit file into an ICC profile. The proposed system works by analyzing the proprietary edit information and then incorporating this information into an input profile. The application of the input profile and an output profile then produces a set of processed CMYK values that, when printed on the target printer produce essentially the same result as that achieved through the proprietary route. As a major part of the process relies on the generation of an accurate input profile, a polynomial fitting process and an empirical process are investigated for use in generating the transform relationship. This research also considers the reversibility of the output profile and a process to ensure accurate reversibility of the output profile is presented. A discussion is presented on the choice of rendering intents available and the different situations where each would be appropriate to use. Experimental results are presented for the whole process based on a test transparency that contains an image of a Macbeth ColorChecker chart. Quantitative results are presented to show how an ICC profiled system can be created that mimics a given proprietary reproduction style to within 2ΔE. This research demonstrates how novel image engineering applications can be constructed from within the ICC framework.