Applied Sciences in Graphic Communication and Packaging

Inhaltsverzeichnis

1. Color Science and Technology

   1. Frontmatter

   2. Correlation Between Color Quality Metric and Color Preference of Light Source

      Rui Peng, Yanfen Zhang, Qiang Liu, Qi Wang, Guo Cao

      Abstract

      Existing studies have shown that a linear combination of some color quality metrics can be used to characterize observers’ color preference of light source. In order to study the correlation between metrics and color preference, nine kinds of LED light sources with different correlated color temperature were selected, and the subjective evaluation of color preference for three object scenes under different lighting conditions was obtained by psychophysical experiments. Based on the previous study, the combination of the metrics is optimized by a variety of fitting models. The results show that the Full Spectrum Color Index (FSCI) and its combinations with other metrics can predict the subjective preference well. The results will provide theoretical and methodological reference for the LED light quality evaluation.

   3. Comparison Between Models, Measurement Instruments, and Testing Datasets for Display Characterization

      Lihao Xu, Ming Ronnier Luo

      Abstract

      This paper mainly investigated the performances between different display characterization methods, between different measurement instruments and between different testing datasets. It was found that a hybrid characterization method performed in the linear RGB space gave the highest accuracy while demanded less testing colors. Besides, no significant difference was found by using different measurement instruments on building models, indicating a limited instrumental accuracy is sufficient for characterization of a traditional LCD display. Moreover, a comprehensive dataset including 4096 test colors, i.e. 16 by 16 by 16 nodes was established. MCCC test chart was found to give a similar evaluation accuracy compared to it.

   4. Study on the Relation Between Smartphone Icons with Negative Emotion and Color Influence Factors

      Yanjun Song, Qiang Wang, Yan Shi

      Abstract

      Emotion design for the user interface, especially the user interface of smartphones, directly affects user interaction, and is influencing the future of design development. Negative emotions are negative emotional experience in psychology, such as fear, sadness and anger. However, few researches on smartphone icons with negative emotion are proposed. In this study, questionnaire, frequency analysis and multiple regression analysis were utilized to analyze the relation between smartphone icons with negative emotion and the specific role of four color influence factors: memory color, visual comfort, color saturation and color image, on emotional arousal. The outcome suggests the particular design focus and design principle on smartphone icons with different types of negative emotion.

   5. Relationship of Different Scales for Evaluating the Quality of LED Lighting

      Ke Liu, Yanfen Zhang, Qiang Liu, Guo Cao, Qingming Li, Zheng Huang

      Abstract

      Existing studies used different scales to evaluate the quality of LED lighting by psychophysics experiments, which viewed specific objects. It is believed that for universal lighting, diverse objects are needed to evaluate color quality. In order to produce a suitable factors space to evaluate the quality of universal lighting, a psychophysics experiment was conducted, which used objects of different color or attribute. The experiments were carried out in darkrooms. In total, 44 observers viewed seven groups of objects to evaluate lighting quality. In this paper, factor analysis was used to reduce the large number of scales into fewer underlying independent factors. The results showed that objects of different color or attribute had an impact on visual perception, and three factors dominate visual perceptions: Attraction, Vividness and Warmth. Basing on this finding, a three-factor space was defined. The work was intended to set up a three-factor space as the help for the construction of LED lighting evaluation and application methods.

   6. Performance Comparison of Uniform Color Spaces by Integrating into a Tone Mapping Operator

      Muhammad Usman Khan, Muhammad Safdar, Muhammad Farhan Mughal, Ming Ronnier Luo

      Abstract

      Typically, tone mapping operators are used to map luminance of high dynamic range (HDR) scenes to that of a displayable range. The goal of this study was to compare the performance of different uniform color spaces (CIELAB, IC_TC_P, and Ja_zb_z) by integrating them into a tone mapping operator. The Contrast Limited Adaptive Histogram Equalization-based Tone Mapping Operator (CLAHE-TMO) was used here. For this purpose, the HDR radiance map of a given scene was first constructed from multiple exposures of the scene captured by using an ordinary RGB camera. The radiance map was then transformed to a uniform color space for the application of TMO on its lightness channel. A psychophysical experiment was conducted using pair comparison method to compare performance of different uniform color spaces. Tone mapped images were compared in four different contexts: preference, naturalness, contrast, and texture details. The experimental results are reported here.

   7. Spectral Image Color Separation Algorithm Based on Cellular Yule-Nielson Spectral Neugebauer Model

      Shiwei Liu, Quanhui Tian, Ming Zhu, Zhen Liu

      Abstract

      Spectral Neugebauer has become a focus because the model has specific physical meaning among all the spectral characteristic model of output devices. In order to improve the precision of the model, Spectral Neugebauer was modified by cell-element and Yule-Nielson exponent, which is called the Cellular Yule-Nielson Spectral Neugebauer (abbreviated as CYNSN). Although CYNSN forward model accuracy is high, but the precision and the efficiency of reverse model (that is, spectral image color separation model) is low. Arming to CYNSN reverse model(spectral image color separation), an adaptive CYNSN reverse model was proposed in this article. Compared with the existing model, the experimental results show that the proposed adaptive spectral color separation model has the same accuracy with the existing model, but efficiency has a great improvement, can achieve about 12.83 times as many of the existing model.

   8. The Spectral Characterizing Model Based on Optimized RBF Neural Network for Digital Textile Printing

      Zhihong Liu, Yongjun Liang

      Abstract

      Digital textile printing was appeared in 1980s, which printed directly onto the surface of fabric with digital original by ink-jet printer and got high quality color printing textile. The spectral characterization of printer is the key technology for the textile printing. This paper presented a spectral characterizing model based on RBF neural network, which optimized the RBF neural network by extending the input variables of neural network. Experimental results showed that the 90% spectral errors of testing color samples are less than 0.04, the average spectral error is 0.025, the maximum spectral error is 0.066; while the 90% color differences (ΔE₂₀₀₀) of testing color samples are less than 2.8, the average value is 1.89, the maximum value is 8.5. That means the model could effectively improve the characterization chromaticity and spectral precision.

   9. A Novel Halftone Dot Prediction Model Based on BP Neural Network

      Mengying Liu, Yuanlin Zheng, Ziwei Tang, Wei Wang

      Abstract

      The purpose of this study is to reduce the ready time of offset printing by establishing a halftone dot prediction model (HDPM) based on BP neural network. The input data of HDPM is spectral reflectance data and the output data is dot area percentage of monochrome inks. To make sure the Mean Square Error (MSE) between the trained output data and the original data negligible, some experiments are performed. We obtained a set of results for dot area percentage of monochrome inks. The HDPM has stable performance, but it doesn’t work well under some special conditions, such as ink with black and dark tone. To improve the precision of HDPM, we increase the training samples of the corresponding area. Therefore, the prediction performance of HDPM has improved, and it does increase the efficiency of printing production in some levels.

   10. Research on Spectral Reconstruction Accuracy of Color Reproduction Based on PAC

       Yumei Li, Chuanjie Liu, Songhua He, Haojie Chen, Qiao Chen

       Abstract

       The key of spectrum color reproduction is to study the spectral information of original images, and reconstruct the spectral curve of the target color. The accuracy of reconstructed spectra is influenced by many factors. In order to study the influence factors of reconstruction accuracy, two kinds of color cards Munsell Color Matt and Color Checker Classic were selected as the spectral reflectance data samples, two kinds of linear dimension reduction models of PCA were established and different number basis vectors were selected to separately reconstruct the spectrum. Then the influence of the different models and the basis vector numbers on the reconstruction accuracy was evaluated. The experimental results showed that the accuracy by model one was better than that of model two in RMSE GFC and color difference. In two kinds of color cards, when the number of basis vectors obtained by model one reached 6, the color difference was less than 1, the RMSE was less than 0.01; the GFC was up to 0.999. So the optimal scheme of reconstructing spectral images is to select spectral dimension reduction model one and 6 basis vectors.

   11. The Influence of Individual Color Preference on LED Lighting Preference

       Yang Tang, Dan Lu, Yijing Xun, Qiang Liu, Yanfen Zhang, Guo Cao

       Abstract

       The individual color preference plays an important role in visual experience. Therefore, a rigorous psychophysical experiment was carried out to investigate the influence of the individual color preference on lighting preference. 45 observers (age from 19–25) were selected from 318 valid questionnaires including three categories of people (15 students categorically preferred blue, 15 students categorically preferred green and 15 students categorically preferred red). The observers made corresponding subjective preference scores with 7-level rating scale on five experimental objects severally illuminated by five spectral power distributions (SPDs) of LED light with different correlated color temperatures (CCTs). Afterwards we used various statistical methods on 1125 sets of data and it was found that the individual color preference had a significant influence on lighting preference but it was not the crucial factor. Compared with this, the results emphasized the dominate influence of the light of CCTs on lighting preference.

   12. A Novel Approach to Skin Coloration on Displays

       Muhammad Farhan Mughal, Mengmeng Wang, Ming Ronnier Luo

       Abstract

       Cosmetics are used as makeup to enhance the impact of appearance. Individuals like to make strong impression on others from their appearance. Current study is based on facial make-up in two color colorimetric attributes “whiteness” and “hue composition” in CIELAB color space. A workflow was implemented to achieve the facial makeup based on color image processing. From facial images against a fixed gray background, skin colors were extracted and transformed to tristimulus XYZ values via a camera characterization model. The XYZ values were used to calculate CIELAB L*, a*, b* color coordinates. They were then converted to L*, \(D_{ab}^{*}\), \(h_{ab}\) color attributes to render whiteness and hue. Using the workflow, the images based on different facial whiteness level and hue angle were successfully rendered.

   13. Performance Analysis of Color Measurement System Based on Spectrometer

       Xiaochun Wang, Guangxue Chen, Guhong Liu, Kaili Zhang

       Abstract

       Spectral measurement tools are the most widely used color measurement instrument, its various advantages will affect the operator to distinguish colors directly. Although instruments are tested before products come on to the market, but in the using process, instrument will change over time, the instrument will aging gradually, leads to the deviation of color measurement. In order to ensure the accuracy of the measurement, it is very important to calibrate instruments after using a long time. The Lab value of 14 BCRA samples was measured using a marine optical USB4000 spectrometer, a marine optical HL-2000 light source, an optical fiber and a reflective probe, a reflection measurement support, and a standard whiteboard. Using the color difference formula, CIE1976 color difference formula, XYZ value and the mean difference to evaluate the repeatability, reproducibility, accuracy and indication error of the color measurement system. Finally, the conclusions were drawn good overall performance of the spectrometer.

   14. A Color Prediction Model for Halftone Print Based on Light Scattering Effect

       Tingli Liu, Guangxue Chen

       Abstract

       Considering the translucency of paper and the non-optical contact between the paper and the backing, this study aims at modeling light scattering in order to improve the prediction of the reflection spectra of photoengraving prints, to fetch the explicit expression around the empty space between the printing materials, and to determine the reflectance of the dot parts and photoengraving printing materials in accordance with measure the MTF of paper and calculate point spread function of paper. Furthermore, a new algorithm for color prediction is established. Compared with the practically checked spectral reflectivity of the photoengraving printing materials proof by using spectrophotometer, the precision of the model shown in this paper is greatly verified.

   15. Analysis of the Color Appearance Model of CIECAM02 Based on OSA-UCS Data

       Wenbing Yang, Xiaoxia Wan

       Abstract

       The visual uniformity of color space has an important influence on the color difference calculation and color gamut mapping algorithm, so it is necessary to make a qualitative and ration evaluation of the spatial visual uniformity of the CIECAM02 color appearance model. On the basis of known CIECAM02 can predict the color appearance in different environments, OSA-UCS data set was used to analyze the degree of uniformity of CIECAM02 color appearance space. Through the experimental samples, select the data set of 13 color samples with the center color sample, and 12 adjacent color samples with equal visual difference. Each quadrant contains five sets of data, a total of forty sets of group data. T after examination and analysis, the uniformity of the fourth quadrant and the eighth quadrant of the yellow and red color space is better than the other color space, while the third and the seventh quadrant of the blue and red color space uniformity is the worst. Therefore, the overall uniformity of the CIECAM02 color space is not good and needs to be optimized.

   16. Reliability of MacAdam Color Discrimination Ellipses

       Jing Liang, Ming Ronnier Luo, Guihua Cui

       Abstract

       The goal of this paper is to investigate reliability of the MacAdam color discrimination ellipses. 1176 pairs of chromatic color difference that was presented on a display. Sampling was done in CIELAB color space. 20 observers assessed the differences using the ratio method. Each pair was assessed against two different backgrounds (a black background and a grey background). Various existing color spaces were tested by the results. It was found that CAM02-UCS performed the best to predict color difference against a grey background. The performance of the CIELAB color space performed the best to predict color difference against a black background. The current experimental ellipses were compared with the original MacAdam ellipses. Both sets had quite different patterns.

   17. The Method for Distinguishing the Holographic Master Masks with Different Micro-structures

       Bingjie Shi, Min Huang, Zeyang Li, Xiaohui He, Ruili He, Yusheng Lian

       Abstract

       In order to distinguish the holographic master masks from different micro-structures, the X-Rite MA68 II multi-angle spectrophotometer was selected to measure the colorimetric values and spectral power distributions of the same point with different angles on the holographic master masks. They started angles of different holographic master masks were adjusted by the colorimetric values L^*, and then the micro-structures can be detected by the shape and location of the peak value of the measured spectral power distribution with the theory of grating equation.

   18. Comparison of Two Methods for Color-Normal Observer Variability in Color Discrimination

       Ruili He, Min Huang, Chunjie Shi, Bingjie Shi, Peipei Ran, Yusheng Lian

       Abstract

       In order to compare the validation of different methods for observers’ color discrimination, 53 observers with normal color vision were organized to carry out two experiments including the Farnsworth Munsell 100 Hue test and the color matching experiment which have been used widely. Four dominant colors (red, yellowish green, turquoise green and bluish purple) in the FM 100 Hue test were selected as the reference colors in color matching experiment. The results were expressed by the total error scores, the mean CIE DE2000 color difference values and the colorimetric ellipses, which indicated that the results of two experiments were not accorded completely for a given color normal observer. The obtained data and three indexes are useful to understand the relationship between these two tests.

   19. Characterization and Evaluation of Color Gamut Boundary Description Algorithm for Output Equipment

       Meiqi Lin, Maohai Lin, Ben Liu, Guichun Hu

       Abstract

       The color gamut boundary description algorithm is used to describe the size of the color gamut boundary and ensure the accurate prerequisite for the conversion of the color gamut mapping. With the development of the research, the application scope and content of the color gamut boundary description are becoming more and more extensive. Firstly, the paper summarizes the development of the color gamut boundary extraction algorithm, characterizes the realization principle of the color gamut boundary description algorithm and predicts the color transfer range which can be achieved by a given color reproduction medium. And then the method of color boundary description algorithm and color gamut mapping algorithm was studied. Finally the paper put forward the views and assumptions in allusion to the problems in the practical application.

   20. An Evaluation Method for the Color Quality of Digital Hardcopy Output SRGB Image

       Shuai Shao, Yanfang Xu, Zhongyue Da, Xinggen Qian, Shun Pan, Yan Li, Bingjie Shi, Peipei Ran, Ruili He

       Abstract

       Aim at evaluating effectively the color quality of digital hardcopy output sRGB images, the assessment method for color quality of digital hardcopy output sRGB images is established. It focuses on the memory color, which designs the assessment color targets to reflect the chroma characteristics of typical memory color (skin color, sky blue color, grass green and cole flower yellow color), it combines the subjective evaluation experiment to ensure the compared scale for chromatic value of color targets of each typical memory color. It carries out the compared analysis for the assessment color lump and chromatic value of actual output and the compared scale, gives out the evaluation of the color quality of hardcopy output sRGB images from three aspects of lightness, chroma and hue. The established method not only can evaluate effectively the color quality of digital hardcopy output sRGB images, but also can provide the technical support for improving and optimizing the color quality of hardcopy output.

   21. The Experimental Research on Color Gamut Transformation Method Based on Different Types of Images

       Peipei Ran, Wenjie Yang, Zhongyue Da, Zhen Liu, Ruili He, Min Huang

       Abstract

       Different color devices can display different color range and the image color passed in different devices can not accurately reproduce too. In order to minimize these differences, the gamut mapping techniques are required. The theories of gamut are basis of the paper and five types of images are mapped, the converted image are evaluated and analyzed to finalize appropriate color gamut mapping method. The experimental results will have a significant meaning for color reproduction and color management.