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A model for simulation of color vision deficiency and a color contrast enhancement technique for dichromats; Um modelo para simulação das deˇciências na percepção de cores e uma técnica de aumento do contraste de cores para dicromátas

Machado, Gustavo Mello
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Dissertação Formato: application/pdf
ENG
Relevância na Pesquisa
36.36%
As Deficiências na Percepção de Cores (DPC) afetam aproximadamente 200 milhões de pessoas em todo o mundo, comprometendo suas habilidades para efetivamente realizar tarefas relacionadas com cores e com visualização. Isto impacta significantemente os âmbitos pessoais e profissionais de suas vidas. Este trabalho apresenta um modelo baseado na fisiologia para simulação da percepção de cores. Além de modelar visão de cores normal, ele também compreende os tipos mais predominantes de deficiências na visão de cores (i.e., protanopia, deuteranopia, protanomalia e deuteranomalia), cujas causas são hereditárias. Juntos estes representam aproximadamente 99.96% de todos os casos de DPC. Para modelar a percepção de cores da visão humana, este modelo é baseado na teoria dos estágios e é derivado de dados reportados em estudos eletrofisiológicos. Ele é o primeiro modelo a consistentemente tratar visão de cores normal, tricromacia anômala e dicromacia de modo unificados. Seus resultados foram validados por avaliações experimentais envolvendo grupos de indivíduos com deficiência na percepção de cores e outros com visão de cores normal. Além disso, ele pode proporcionar a melhor compreensão e um feedback sobre como aperfeiçoar as experiências de visualização por indivíduos com DPC. Ele também proporciona um framework para se testar hipóteses sobre alguns aspectos acerca das células fotoreceptoras na retina de indivíduos com deficiência na percepção de cores. Este trabalho também apresenta uma técnica automática de recoloração de imagens que visa realçar o contraste de cores para indivíduos dicromatas com custo computacional variando linearmente com o número de pixels. O algoritmo proposto pode ser eficientemente implementado em GPUs...

The contribution of color during object recognition: behavioral, electrophysiological and neuroimaging evidence

Bramão, Inês
Fonte: Universidade do Algarve Publicador: Universidade do Algarve
Tipo: Tese de Doutorado
Publicado em //2011 ENG
Relevância na Pesquisa
36.37%
Tese de dout., Psicologia, Faculdade de Ciências Humanas e Sociais, Univ. do Algarve, 2011; In this thesis, we present six studies that investigated the role of color information during visual object recognition. The interactions between surface color and color knowledge information were investigated in two studies (chapters 2 and 3). In chapters 4 and 5, we present data that identify the visual processing stage at which color information improves color and non-color diagnostic object recognition. In chapter 6, the neural pathways supporting color object recognition were investigated. Additionally, in an attempt to bring some consistency to the literature, we performed a systematic meta-analysis on the effects of color on object recognition in chapter 7. Chapter 2 and 3 provided data suggesting that surface color information is more influential than color knowledge information during object recognition. Chapter 4 and 5 showed that color information improves the recognition of color and non-color diagnostic objects at different stages of visual processing. Although color information is an important cue for both of these types of objects in the early visual processes, it is also important in later stages of visual processing for color diagnostic object recognition. In chapter 6...

Evaluación de dos sistemas de medición de color en filetes de salmónidos

Carrió Maldonado, Renato Alonso
Fonte: Universidad de Chile Publicador: Universidad de Chile
Tipo: Tesis
ES
Relevância na Pesquisa
36.36%
Memoria para optar al Título Profesional de ingeniero Agrónomo. Mención: Producción Animal; El color de la carne de salmónidos es uno de los parámetros de calidad más importante, pero su medición es compleja. En el presente estudio se evaluaron los sistemas de medición visual (cartilla Roche™ y regla Salmofan) e instrumental (fotocolorímetro triestímulo Minolta Chroma Meter) del color de la carne en salmónidos. Se estudió la precisión (repetibilidad y reproducibilidad) de ambos métodos, la relación entre estos y la relación entre la medición de color con el contenido de pigmento y lípidos. Además, se comparó la variabilidad entre dos fotocolorímetros con distinta área de medición. La precisión de ambos métodos se evaluó en tres plantas de proceso ubicadas en Chiloé, midiendo filetes de trucha arcoíris (Oncorhynchus mykiss) y salmón del Atlántico (Salmo salar) en forma repetida y aleatoria. Las mediciones se hicieron con la luz normal de la planta y luz D65 en cabina de iluminación controlada. El efecto del área de medición de los fotocolorímetros se evaluó sobre filetes de salmón del Atlántico en el centro Colaco de la empresa EWOS S.A. La relación entre contenido de pigmento...

Using color management to automate the color reproduction of 3-D images procured via a digital camera/3-D scanner

Honda, Kristl
Fonte: Rochester Instituto de Tecnologia Publicador: Rochester Instituto de Tecnologia
Tipo: Tese de Doutorado
EN_US
Relevância na Pesquisa
36.39%
The use of digital photography is migrating from the major applications in pho tojournalism to professional studio photography. Traditional service bureaus such as professional photo labs and prepress trade shops are adding digital imaging services to their film-based services. Also, businesses such as advertising agencies and publishers, who traditionally outsource work to service bureaus, are bringing digital imaging services in-house. State of the art imaging technology empowers users with new tools, but does not guarantee that the task of generating accept able image reproductions will be easier. The basic problem in the desktop color prepress environment is that each com ponent in this open system handles color differently. Miscommunication between devices results in user frustration with an unpredictable, inconsistent, and inaccurate color system. The solution to this problem is to assess one's workflow and adopt a color management system (CMS). The purpose of CMSs is to help users maintain color integrity throughout their desktop system and to automate the color separation process. This thesis project investigated the possibility of applying a comprehensive CMS to automate the color reproduction of 3-D images procured with a digital camera. Automatic exposure by Leaf System's Lumina digital camera and automatic adjustments for tone reproduction...

The Study of using the banded anilox roller for color matching in flexography

Puvaravutipanich, Apichai
Fonte: Rochester Instituto de Tecnologia Publicador: Rochester Instituto de Tecnologia
Tipo: Tese de Doutorado
EN_US
Relevância na Pesquisa
36.38%
Color matching is an important issue in the flexographic industry today because of many problems related to it. For example, there are few standards of ink and color for spot color printing. Further, there is no standardization in the communication among anilox roller suppliers and their customers concerning the specific cell volume measurement of the anilox roller. This research focused on the study of the use of the banded anilox roller as a tool for color proofing under the assumption that a spot color printed by the flexographic process actually should be produced using a banded anilox roller as a tool for color proofing. The major questions for this study were: 1. How will the anilox cell volume and line screen per inch affect the CIE LAB total color difference (AE) ? 2. Can the same color actually be produced with a AE < 2 (good match) by using the same specification of anilox roller? This research was conducted by printing a spot color with two banded anilox rollers to match the original Pantone color as close as possible and using it for the reference. The data collected from each of the bands was plotted in diagrams to see the effects of cell volume and line screen per inch on the total color difference(AE). In this experiment...

Uniform color spaces based on CIECAM02 and IPT color difference equations

Xue, Yang
Fonte: Rochester Instituto de Tecnologia Publicador: Rochester Instituto de Tecnologia
Tipo: Tese de Doutorado
EN_US
Relevância na Pesquisa
36.37%
Color difference equations based on the CIECAM02 color appearance model and IPT color space have been developed to fit experimental data. There is no color space in which these color difference equations are Euclidean, e.g. describe distances along a straight line. In this thesis, Euclidean color spaces have been derived for the CIECAM02 and IPT color difference equations, respectively, so that the color difference can be calculated as a simple color distance. Firstly, the Euclidean line element was established, from which terms were derived for the new coordinates of lightness, chroma, and hue angle. Then the spaces were analyzed using performance factors and statistics to test how well they fit various data. The results show that the CIECAM02 Euclidean color space has performance factors similar to the optimized CIECAM02 color difference equation. To statistical significance, the CIECAM02 Euclidean color space had superior fit to the data when compared to the CIECAM02 color difference equation. Conversely, the IPT Euclidean color space performed poorer than the optimized IPT color difference equation. The main reason is that the line element for the lightness vector dimension could not be directly calculated so an approximation was used. To resolve this problem...

Influence of ink sequence on color's hue and saturation in four color halftone screen printing

Bougàs, Aristotelis Platon
Fonte: Rochester Instituto de Tecnologia Publicador: Rochester Instituto de Tecnologia
Tipo: Tese de Doutorado
EN_US
Relevância na Pesquisa
36.38%
The screen printing process has been the least understood and studied versus other imaging methods in the graphic arts industry. As equipment configurations improve and a continuous technological development and need for high quality output persists, this fascinating process becomes increasingly popular in several end-use applications. Such as in packaging, labeling, durable graphic films printing and even short run large format halftone graphics. There is a serious need for further deep scientific analysis of the process and its variables. One of the poorly investigated sides of the four color screen printing is the effect that ink placement has to the final color appearance of a halftone print. Several known factors can influence the color result of a screen printed image. Limitations inherent to screen printing allow for a smaller color gamut reproduction compared to other methods, but colors are reproduced vividly due to a uniform and high ink film thickness. The screen - equivalent to a printing plate - consists of a stretched porous fabric mounted on a carrier frame that is coated with a light sensitive emulsion (stencil) and subsequently exposed and hardened at the non image areas. The ink will flow through the screen mesh openings when pressure and hydraulic forces are applied by a squeegee blade system. The ink system can be cured or dried by various methods depending on its chemistry and composition. For the specific system investigated...

Color difference formula and uniform color space modeling and evaluation

Shen, Shizhe
Fonte: Rochester Instituto de Tecnologia Publicador: Rochester Instituto de Tecnologia
Tipo: Tese de Doutorado
EN_US
Relevância na Pesquisa
36.39%
Defining color tolerances numerically continues to be a topic of intense interest in colorimetry. A technique was developed to evaluate formula performance that incorporated visual uncertainty. In this technique, visual uncertainty was represented by randomized equal color-difference ellipsoids or randomized visual color differences. STRESS, a multivariate statistical tool, was employed to quantify these randomized equal color-difference ellipsoids or visual color differences. The STRESS clouds were composed of the STRESS values between the randomized equal color-difference ellipsoids and T50 equal color-difference ellipsoids, or between the randomized visual color differences and T50 visual color differences where T50 represented visually determined tolerances equivalent to an anchor-pair stimulus. These STRESS values clouds were taken as rulers to evaluate whether one color-difference formula over-, under- or well-fitted a specified color-difference dataset, based on an F-test. This technique is a necessary addition to the current deviation evaluation metrics, e.g., PF/3. In follow-on research, a Euclidean color space was developed with the color-difference formula based on IPT color space for supra-threshold color differences. The color-difference formula has similar chromatic modeling to CIE94. A lightness transformation function was applied to model color difference along lightness. A rotation matrix on the chromatic plane was also applied to achieve better characteristics of the color space. A step-wise optimization was performed to achieve better consistency and remove conflicts between different color-difference datasets. The evaluations include STRESS...

A study of matching the color of EPSON Stylus COLOR 3000 to ANSI CGATS TR 001-1995 - type 1 printing

Chan, Joel
Fonte: Rochester Instituto de Tecnologia Publicador: Rochester Instituto de Tecnologia
Tipo: Tese de Doutorado
EN_US
Relevância na Pesquisa
36.39%
ICC color management system (CMS) has become a major tool for color image rendering and color matching in the printing and publishing industry. It attempts to automate color management functions, e.g., from scan to print, and from press sheet to proof, with the use of device profiles, a CMM, and an application programming interface. Earlier studies, conducted at RIT, showed that ICC-based digital proofing did not perform better than a well calibrated film-based proofing system. Specifically, the average AE between ICC color managed proofs and a reference press sheet was found to be 6-9 while the average AE between a film based proof and its correspondence press sheet was 5. Realizing that sources of AE errors exist in many places, e.g., printing consistency, proofer's color gamut, proofing consistency, measurement conditions, this paper discussed an improved methodology for testing the performance of color matching in a digital proofing workflow. The source profile was a SWOP press profile, supplied by Kodak, which characterizes the ANSI CGATS TR 001-1995 - Type 1 Printing condition. The destination profile was built from an Epson SC3000 ink jet printer using the Kodak Colorflow ProfileEditor at the printer's default color gamut. The IT8.7/3 basic (CMYK) target was transformed with the use of the Mac OS...

The Effects of fluctuations in solid ink density on color variation for conventional and grey component replacement separations when printing process color on newsprint

Pawlow, Eric Matthew
Fonte: Rochester Instituto de Tecnologia Publicador: Rochester Instituto de Tecnologia
Tipo: Tese de Doutorado
EN_US
Relevância na Pesquisa
36.38%
A color separation technique known as Gray Component Replacement, or GCR has been an option available to high-end drum scanner operators for the past eight years. Recently, GCR has been made available by lower-end color system vendors as well. GCR consists of removing the least predominant process color ink in a unit area, reducing the remaining colored inks by the same amount and replacing the "gray component" of the color with black ink. One of the reported benefits of the GCR technique is that more consistency can be realized during a pressrun. If this is in fact true, the first publication printers who would surely utilize the technique would be newspapers. The problem of consistency is particularly acute for newspapers. There are a number of reasons for this, but the primary ones relate to the types of materials used. Newspapers use the cheapest paper and ink and in many cases, they print with old or poorly maintained presses. They would surely welcome any process that offered better reproductive quality and more consistency, provided the investment was justifiable. Since their present color separation systems allow for the use of GCR in the majority of cases, its potential in the area of newspaper printing was investigated in this study. One factor determining consistency during a pressrun is the control of ink film thickness. As ink film thickness fluctuates...

A Comparison of the photochemical reproduction quality from color negative films versus color transparency films

DuBois, Dawn
Fonte: Rochester Instituto de Tecnologia Publicador: Rochester Instituto de Tecnologia
Tipo: Tese de Doutorado
EN_US
Relevância na Pesquisa
36.4%
Color transparency film is the most frequently used original material in the color separation process. Recent technological advances in color negative film and electronic color generated scanners capable of working from a color negative have led to new avenues of exploration in the area of color separation. By using a color negative film as the original it may be possible to produce color separations of equal or higher quality than those produced from color transparencies. This research project has investigated the possibility that a set of color separations made from an Eastman Kodak Ektar color negative could yield a set of color separation proofs of equal or superior quality to those made from an Eastman Kodak Kodachrome color transparency. The attributes that were investigated were image detail, color saturation and tone reproduction. A total of six original scenes were photographed by the author; six using Kodachrome 25- 35mm slide film- and six using Ektar 25-35 mm negative film. Four of the original images were photographed at the same time in a controlled studio environment. The remaining two images were photographed outdoors to include a normal exterior scene. Twelve color separations were then generated using the Royal Zenith 210-L color scanner. These twelve separations were then proofed using the DuPont Cromalin proofing system. The last stage of the study involved a visual evaluation by thirty judges with professional experience in either the fields of photography or printing. Under standard viewing conditions...

Test Targets 3.1: A Collaborative effort exploring the use of scientific methods for color imaging and process control.

Chung, Robert; Chun, Edline; Kang Ha, Seunga; Hsu, Chao-Yi; Kolli, Hemachand; Kong, Lingjun; Lesser, Jon; Shetty, Somika; Testa, Ryan; Gupta, Vikaas
Fonte: RIT School of Print Media Publicador: RIT School of Print Media
Tipo: Periódico Formato: 3174676 bytes; iii, 58 p. : col. ill. ; 27 cm. Cover printed on the Heidelberg 6-color SpeedMaster sheetfed press using Sappi Somerset Lustro Gloss, 80 lb. cover stock. Text printed on the Heidelberg Sunday 2000 web offset press using Sappi Somerset Gloss
EN
Relevância na Pesquisa
36.39%
In general, test targets represent known values from an object or in a digital file, e.g., color patches, digital dots, lines with known dimensions, etc. The Macbeth ColorChecker is an analog target with 24 physical color patches. When captured by an input device and reproduced by an imaging system, we can compare tone and color relationships between the source target and its reproduction. On the other hand, the IT8.7/3 target is a digital file consisting of hundreds of patches with known CMYK digital values. When printed along side a signature, we can assess print quality quantitatively with the use of optical instruments and associated analysis techniques. - p. ii.; Part One: Digital imaging and color management / by Robert Chung - Test targets 3.1: an editorial persective / by Edline M. Chun - Color management system lab introduction / by Seunga Kang Ha - Colorimetric comparison between generic and custom press profiles / by Chao-Yi Hsu - Colorimetric analysis of color image reproductions / by Hemachand Kolli - Effect of sample backing on the accuracy of color measurement / by Lingjun Kong - Spot color matching in ICC color managed workflows / by Seunga Kang Ha - Panorama photography / by Jon Lesser - Role of image content in objective color matching / by Somika Shetty - Comparison of color conversion between Photoshop and ICC CMS / by Ryan Testa - Color matching between Pantone and ICC profiles / by Vikaas Gupta. Part Two: TF_01 Device characterization target - TF_02 Pictorial reference images - TF_03 Synthetic targets - TF_04 Screening targets - TF_05 IT 8.7/3 target - TF_06 GretagMacbeth profiling target - TF_07 Monaco profiling target - TF_08 Fujifilm profiling target - TF_09 Kodak profiling target - TF_10 ECI profiling target - TF_11 TAC chart - TF_12 Contrast resolution target; Guiding and producing a technical publication; New tool for quantitative comparison of color differences; Effect of GCR and TAC in color gamut volume; Comparison of color gamut and amplitude responses between AM and FM screening; Analysis of ink dry down for hexachrome inks for sheeted offset printing; Measuring the variation of a digital printer; Comparing color image capture using film transparencies and digital cameras; Real-world color management journey in commercial printing; AM and FM screening; Studying resolution and contrast; Color matching comparison between generic and custom press profiles; Colorimetric analysis of color image reproduction; Test targets 3.0 cover: from design to print production; CMS: from press run analysis to a color-managed workflow; “Test Targets is a peer-reviewed publication. The content reflects scholarship and is the property of the publisher and the author. To reprint any part of the publication...

Test Targets 4.0: A Collaborative effort exploring the use of scientific methods for color imaging and process control

Chung, Robert; Chun, Edline; Sigg, Franz; Costa, Tiago; Janjomsuke, Wiphut; Techavichien, Nattawan; Vogl, Howard; Berkow, Eric; Caruso, Doug; Kim, Rochelle; Zolan, Gregory
Fonte: RIT School of Print Media Publicador: RIT School of Print Media
Tipo: Periódico Formato: 9312590 bytes; 78 p. : col. ill. ; 27 cm. Cover printed at RIT's Printing Applications Laboratory on the Heidelberg Speedmaster 74 Sheetfed Press. Insert printed at RIT's Printing Application Laboratory on the Heidelberg Speedmaster 74 Sheetfed Press. Te
EN
Relevância na Pesquisa
36.39%
Test Target 4.0 (TT4.0) is the result of student teamwork to publish a technical journal for a graduate-level course titled: Advance Color Management (Course no. 2081-735-03). Offered by the School of Print Media (SPM) at Rochester Institute of Technology (RIT), the course is "a platform to experiment and to realize a new digital imaging paradigm and the dynamics of teamwork...." Team members learn scientific methodology in process control for repeatable color as well as apply ICC-based color management practices in digital workflows. They plan and conduct press run analyses reported in TT4.0, which is printed using facilities available at RIT. In producing this publication, the team learns to integrate design, content creation, digital media, and print production in a seamless workflow.... -p. 4.; Introduction and acknowledgements / by Robert Chung - Guiding and producing a technical publication / by Edline M. Chun - A New tool for quantitative comparison of color differences / by Franz Sigg - Effect of GCR and TAC in color gamut volume / by Tiago Costa - Comparison of color gamut and amplitude responses between AM and FM screening / by Wiphut Janjomsuke - Analysis of ink dry down for hexachrome inks for sheetfed offset printing / by Nattawan Techavichien - Measuring the variation of a digital printer / by Howard Vogl - Comparing Color image capture using film transparencies and digital cameras / by Eric Berkow - A Real-world color management journey in commercial printing / by Doug Caruso - Reproducing a process color...

Analysis of color errors and their sources in a commercial color reproduction process

Sakda Siriphan
Fonte: Rochester Instituto de Tecnologia Publicador: Rochester Instituto de Tecnologia
Tipo: Tese de Doutorado
EN_US
Relevância na Pesquisa
36.37%
To analyze color errors and their sources in the color reproduction process, the reproduction is visually evaluated and compared visually with the original scene color scales and also with the original transparency viewed on a variable brightness illuminator (D5000) with an opaque reflective white surround. Graphs (press plate curves, single color proofs and END of single color proofs) have been added to the Kodak tone-reproduction diagram (1960) to obtain more complete steps in the analysis of the tone-reproduction and the color balance. The GATF Evaluation Method of Ink Color is tested and the GARC colorimetric system, which is a modified Adam’s chromatic value system, is used to analyze colorimetric measurement. The slightly dark reproduction, the shift of the color balance to bluish cyan in the reproduction; the shift of hues, the magenta toward red, the cyan and the green toward blue; and the desaturation of the blue, the cyan and the yellow are discovered as errors in the reproduction. The possible improvements of these errors are discussed. The hope to combine the tone-reproduction analysis, the GATF Evaluation of Ink Color and the GARC colorimetric system into one system of analysis of the color errors is not fulfilled, because the mask percentages obtained from the Evaluation of Ink Color do not agree with that of the reproduction process and the hue error and grayness of the Evaluation of Ink Color do not correspond with the visual hue and the color saturation. However...

A Study of the color management implementation on the RGB-based digital imaging workflow: digital camera to RGB printers

Sa-areddee, Darunee
Fonte: Rochester Instituto de Tecnologia Publicador: Rochester Instituto de Tecnologia
Tipo: Tese de Doutorado
EN_US
Relevância na Pesquisa
36.37%
An RGB (red, green, and blue color information) workflow is used in digital photography today because a lot of the devices digital cameras, scanners, monitors, image recorders (LVT or Light Value Technology), and some types of printers are based on RGB color information. In addition, rapidly growing new media such as the Internet and CD-ROM (Compact Disc-Read-Only Memory) publishing use an RGB -based monitor as the output device. Because color is device-dependent, each device has a different method of representing color information. Each has a different range of color they can reproduce. Most of the time, the range of color, color gamut, that devices can produce is smaller than that of the original capturing device. As a result, a color image reproduction does not match accurately with its original. Therefore, in typical color image reproduction, the task of matching a color image reproduction with its original is a significant problem that operators must overcome to achieve good quality color image reproduction. Generally, there are two approaches to conquer these problems. The first method is trial-and-error in the legacy-based system. This method is effective in a pair-wise working environment and highly depended on a skill operator. The second method is the ICC-based (ICC or International Color Consortium) color management system (CMS) which is more practical in the multiple devices working environment. Using the right method leads to the higher efficiency of a digital photography produc tion. Therefore...

Exploring the color inconstancy of prints

Chen, Yongda; Berns, Roy; Taplin, Lawrence
Fonte: Association Internationale de la Couleur (AIC) - International Color Association Publicador: Association Internationale de la Couleur (AIC) - International Color Association
Tipo: Artigo de Revista Científica
EN_US
Relevância na Pesquisa
46.33%
The color inconstancy of prints is related to the ink spectral properties and the lookup table for multiink printing systems. In this paper, color inconstancy was investigated for several ink-jet printers based on their ink set and the default lookup tables. A virtual model for each printer was created to determine the range of color inconstancy that a specific ink set could achieve. The color inconstancy performance of each default lookup table was evaluated by evaluating the color inconstancy of a printed test target. The optimum combinations of three- and four-chromatic inks were investigated to minimize the color inconstancy and keep a relative large color gamut simultaneously. The results showed that the color inconstancy can be decreased significantly without compromising the reproduction colorimetric accuracy. Moreover the color inconstancy can be improved by appropriate ink design.; "Exploring the color inconstancy of prints," Proceedings of the Tenth Congress of the International Colour Association. Held in Granada, Spain: 8-13 May 2005.; none

Evaluating the 1931 CIE color-matching functions

Shaw, Mark; Fairchild, Mark
Fonte: Wiley InterScience: Color & Research Application Publicador: Wiley InterScience: Color & Research Application
Tipo: Artigo de Revista Científica
EN_US
Relevância na Pesquisa
46.34%
The use of colorimetry within industry has grown extensively in the last few decades. Central to many of today's instruments is the CIE system, established in 1931. Many have questioned the validity of the assumptions made by Wright1 and Guild,2 some suggesting that the 1931 color-matching functions are not the best representation of the human visual system's cone responses. A computational analysis was performed using metameric data to evaluate the CIE 1931 color-matching functions as compared to with other responsivity functions. The underlying assumption was that an optimal set of responsivity functions would yield minimal color-difference error between pairs of visually matched metamers. The difference of average color differences found in the six chosen sets of responsivity functions was small. The CIE 1931 2° color-matching functions on average yielded the largest color difference, 4.56 E. The best performance came from the CIE 1964 10° color-matching functions, which yielded an average color difference of 4.02 E. An optimization was then performed to derive a new set of color-matching functions that were visually matched using metameric pairs of spectral data. If all pairs were to be optimized to globally minimize the average color difference...

Observer variability in metameric color matches using color reproduction media

Alfvin, Richard; Fairchild, Mark
Fonte: Wiley InterScience: Color Research & Application Publicador: Wiley InterScience: Color Research & Application
Tipo: Artigo de Revista Científica
EN_US
Relevância na Pesquisa
46.34%
Standard color-matching functions are designed to represent the mean color-matching response of the population of human observers with normal color vision. When using these functions, two questions arise. Are they an accurate representation of the population? And what is the uncertainty in color-match predictions? To address these questions in the dual context of human visual performance and cross-media reproduction, a color-matching experiment was undertaken in which twenty observers made matches between seven different colors presented in reflective and transmissive color reproduction media and a CRT display viewed through an optical apparatus that produced a simple split-field stimulus. In addition, a single observer repeated the experiment 20 times to estimate intra-observer variability. The results were used to evaluate the accuracy of three sets of color-matching functions, to quantify the magnitude of observer variability, and to compare intra- and inter-observer variability in color-matching. These results are compared with various techniques designed to predict the range of color mismatches. The magnitude of observer variability in this experiment also provides a quantitative estimate of the limit of cross-media color reproduction accuracy that need not be exceeded. On average...

Refinement of the RLAB color space

Fairchild, Mark
Fonte: Wiley InterScience: Color Research & Application Publicador: Wiley InterScience: Color Research & Application
Tipo: Artigo de Revista Científica
EN_US
Relevância na Pesquisa
46.24%
The prediction of color appearance using the RLAB color space has been tested for a variety of viewing conditions and stimulus types. These tests have shown that RLAB performs well for complex stimuli and not-so-well for simple stimuli. This article reviews the various psychophysical results, interprets their differences, and describes evolutionary enhancements to the RLAB model that simplify it and improve its performance.; Article may be found at: http://www.cis.rit.edu/fairchild/PDFs/PAP03.pdf

Considering the surround in device-independent color imaging

Fairchild, Mark
Fonte: Wiley InterScience: Color Research & Application Publicador: Wiley InterScience: Color Research & Application
Tipo: Artigo de Revista Científica
EN_US
Relevância na Pesquisa
46.28%
When viewing images, the relative luminance of the surround has a profound impact on the apparent contrast of the image. For this reason, photographic transparencies intended for projection in a darkened room are produced with an objective contrast substantially higher than that necessary for optimum reproduction as prints viewed in an illuminated surround. The dark surround causes the image elements to appear lighter and this effect is stronger for darker colors resulting in a loss in perceived contrast. This effect is also of great importance in device-independent color imaging since resultant images might be observed in a wide variety of media and viewing conditions. Research on psychophysical scaling of brightness and lightness and the effects of background and surround relative luminance on lightness and chroma is reviewed. The importance of this research for deviceindependent color imaging systems is described along with the prediction of these effects using the RLAB color-appearance model. Finally, experiments testing the use of RLAB and other color-appearance models in cross-media color reproduction applications are described.; RIT community members may access full-text via RIT Libraries licensed databases: http://library.rit.edu/databases/