2,892 research outputs found
A Similarity Measure for Material Appearance
We present a model to measure the similarity in appearance between different
materials, which correlates with human similarity judgments. We first create a
database of 9,000 rendered images depicting objects with varying materials,
shape and illumination. We then gather data on perceived similarity from
crowdsourced experiments; our analysis of over 114,840 answers suggests that
indeed a shared perception of appearance similarity exists. We feed this data
to a deep learning architecture with a novel loss function, which learns a
feature space for materials that correlates with such perceived appearance
similarity. Our evaluation shows that our model outperforms existing metrics.
Last, we demonstrate several applications enabled by our metric, including
appearance-based search for material suggestions, database visualization,
clustering and summarization, and gamut mapping.Comment: 12 pages, 17 figure
Digital Color Imaging
This paper surveys current technology and research in the area of digital
color imaging. In order to establish the background and lay down terminology,
fundamental concepts of color perception and measurement are first presented
us-ing vector-space notation and terminology. Present-day color recording and
reproduction systems are reviewed along with the common mathematical models
used for representing these devices. Algorithms for processing color images for
display and communication are surveyed, and a forecast of research trends is
attempted. An extensive bibliography is provided
Derivation and modelling hue uniformity and development of the IPT color space
Metric color spaces have been determined to be significantly non-uniform in the hue attribute of color appearance. Several independent sources have confirmed the non-uniformity. A data set was obtained during the course of this thesis work that contains the largest sampling of color space to date which can be used to compare models of color appearance. The data set obtained was compared to existing data sets and found to correspond closely. Lookup table methods were employed to test significant differences between data sets. A simple modeling approach was taken based on commonly understood color space models and knowledge of the visual system. Several color spaces can be derived using the simple model, and one was chosen that models hue uniformity very well and has other desirable attributes. This new color space is named IPT. Many visual data sets were plotted in the IPT color space and all show improved performance over industry standard color spaces. The IPT color space has applications in color data representation, gamut mapping, and color appearance modeling
Investigating the Effect of Color Gamut Mapping Quantitatively and Visually
With the advent of various color management standards and tools, the print media industry has seen many advancements aimed towards quantitatively and qualitatively acceptable color reproduction. This research attempts to test one of the most fundamental and integral parts of a standard color management workflow, the profile. The gamut mapping techniques implemented by the ICC profiles created using different profiling application programs were tested for their congruity to the theoretical concepts, standards, and definitions documented by International Color Consortium (ICC). Once these profiling software applications were examined, the significance of the possible discrepancies were tested by establishing a visual assessment of pictorial images using these profiles.
In short, this research assessed the implementations of the ICC color rendering intents in a standard or a commonly used color managed workflow, and then described the significance of these discrepancies in terms of interoperability. For this research, interoperability was defined the assessment of different ICC profiles in producing similar results, i.e., quantitatively and visually. In order to achieve the desired assessment, the two profiling applications were selected and each used to create an output profile using the same characterization data set. The two profiles were then compared for differences in the way they mapped real world colors. The results displayed that even though there were some significant quantitative color differences, visual subjective evaluation did not reflect any noticeable color differences and therefore concluded that the profiles were interoperable. These findings reveal that even though quantitative color differences may reflect significant color differences, subjective visual comparisons may not always reflect the same or agree with quantitative findings
High-fidelity colour reproduction for high-dynamic-range imaging
The aim of this thesis is to develop a colour reproduction system for high-dynamic-range (HDR)
imaging. Classical colour reproduction systems fail to reproduce HDR images because current characterisation
methods and colour appearance models fail to cover the dynamic range of luminance
present in HDR images. HDR tone-mapping algorithms have been developed to reproduce HDR
images on low-dynamic-range media such as LCD displays. However, most of these models have
only considered luminance compression from a photographic point of view and have not explicitly
taken into account colour appearance. Motivated by the idea to bridge the gap between crossmedia
colour reproduction and HDR imaging, this thesis investigates the fundamentals and the
infrastructure of cross-media colour reproduction. It restructures cross-media colour reproduction
with respect to HDR imaging, and develops a novel cross-media colour reproduction system for
HDR imaging. First, our HDR characterisation method enables us to measure HDR radiance values
to a high accuracy that rivals spectroradiometers. Second, our colour appearance model enables us
to predict human colour perception under high luminance levels. We first built a high-luminance
display in order to establish a controllable high-luminance viewing environment. We conducted a
psychophysical experiment on this display device to measure perceptual colour attributes. A novel
numerical model for colour appearance was derived from our experimental data, which covers the
full working range of the human visual system. Our appearance model predicts colour and luminance
attributes under high luminance levels. In particular, our model predicts perceived lightness
and colourfulness to a significantly higher accuracy than other appearance models. Finally, a complete
colour reproduction pipeline is proposed using our novel HDR characterisation and colour
appearance models. Results indicate that our reproduction system outperforms other reproduction
methods with statistical significance. Our colour reproduction system provides high-fidelity colour
reproduction for HDR imaging, and successfully bridges the gap between cross-media colour reproduction
and HDR imaging
Color-coordinate system from a 13th-century account of rainbows.
We present a new analysis of Robert Grosseteste’s account of color in his treatise De iride (On the Rainbow), dating from the early 13th century. The work explores color within the 3D framework set out in Grosseteste’s De colore [see J. Opt. Soc. Am. A 29, A346 (2012)], but now links the axes of variation to observable properties of rainbows. We combine a modern understanding of the physics of rainbows and of human color perception to resolve the linguistic ambiguities of the medieval text and to interpret Grosseteste’s key terms
THE INFLUENCE OF STANDARD RENDERING METHODS ON THE MANIFESTED INTENSITY OF THE CHROMATIC INDUCTION EFFECT
The focus of this work is directed to investigations with the aim of explaining the mutual relationships of parameters connected to the gamut size, rendering methods and the visual evaluations of the prints with the image presentations, which cause the psychophysical effect of the chromatic induction. The results of instrumental analysis in relation to the results of visual evaluation show aberration from the conventional point of view, according to which the increase of gamut size of prints is followed by the increase of the experience quality. In this sense the additional analyses are made and the correlations are determined which define the relationships of the previously mentioned parameters
Print engine color management using customer image content
The production of quality color prints requires that color accuracy and reproducibility be maintained to within very tight tolerances when transferred to different media. Variations in the printing process commonly produce color shifts that result in poor color reproduction. The primary function of a color management system is maintaining color quality and consistency. Currently these systems are tuned in the factory by printing a large set of test color patches, measuring them, and making necessary adjustments. This time-consuming procedure should be repeated as needed once the printer leaves the factory. In this work, a color management system that compensates for print color shifts in real-time using feedback from an in-line full-width sensor is proposed. Instead of printing test patches, this novel attempt at color management utilizes the output pixels already rendered in production pages, for a continuous printer characterization. The printed pages are scanned in-line and the results are utilized to update the process by which colorimetric image content is translated into engine specific color separations (e.g. CIELAB-\u3eCMYK). The proposed system provides a means to perform automatic printer characterization, by simply printing a set of images that cover the gamut of the printer. Moreover, all of the color conversion features currently utilized in production systems (such as Gray Component Replacement, Gamut Mapping, and Color Smoothing) can be achieved with the proposed system
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