Status of CIE Color Appearance Models

In meetings just prior to the 1997 AIC Congress in Kyoto, CIE TC1-37, chaired by M. Fairchild, established the CIE 1997 Interim Colour Appearance Model (Simple Version), known as CIECAM97s. CIECAM97s was formally published in 1998 in CIE publication 131. CIE TC1-37 was dissolved shortly after publication of CIECAM97s at which time, a reportership, R1-24 held by M. Fairchild, was established to monitor ongoing developments in color appearance modeling and notify CIE Division 1 if it became necessary to form a new TC to consider revision or replacement of CIECAM97s. In the four years between AIC Congresses, there has been much activity, both by individual researchers and within the CIE, aimed at furthering our understanding of color appearance models and deriving improved models for consideration. The aim of this paper is to summarize these activities, report on the current status of CIE efforts on color appearance models, and suggest what the future might hold for CIE color appearance models

Spectral Adaptation: A Reason to Use the Wavenumber Scale

Chromatic adaptation refers to the ability of the human visual system to adjust to the color of the illumination, or other prevailing stimuli, such that perceived object colors vary far less with changes in illumination than would be expected from simple radiometry or colorimetry. Models of chromatic adaptation are generally formulated as extensions of the von Kries hypothesis of some sort of independent gain control mechanisms operating on the three types of cone signals. This paper introduces a new way to model the phenomenon with no requirement for the first stage chromatic processing. This model is referred to as a spectral adaptation model since it acts upon spectra rather than chromatic signals such as tristimulus values. The spectral adaptation model was compared with other models of adaptation both computationally and through limited psychophysical data. It is shown to have reasonable, and flexible, performance and could be of practical value in applications such as spectral image reproduction. A limiting case of the spectral model, a model of perfect color constancy, is also described and compared with traditional chromatic adaptation models

A Color Scientist Looks at Video

This paper represents a critical review of some of the color processing in the consumer TV processing chain. As such, a default processing chain is assumed as a starting point. The flow of color image information through this chain is described and critiqued. That is followed by development and description of some “clean slate” theoretical approaches to video processing with color accuracy and quality as the highest priority. These two approaches are compared and contrasted to provide some practical insight into how color science could be used in a practical sense to improve consumer video processing. Additionally, some examples how color and image appearance models might be used in the development of consumer video systems are described

Observer metamerism: Why do [mis]matches of neutral appear pinkish or greenish?

White lighting and neutral-appearing objects are essential in numerous color applications. In particular, setting or tuning a reference white point is a key procedure in both camera and display applications. Various studies on observer metamerism pointed out that noticeable color disagreements between observers mainly appear in neutral colors. Thus, it is vital to understand how observer metamers of white (or neutral) appear in different colors by different observers. Most observers who participated in a visual demonstration reported that white observer metamers appear pinkish or greenish but rarely yellowish or bluish. In this paper, this intriguing question, “Why observer metamers of white are usually pinkish or greenish?,” is addressed based on simulations. Besides, it is also analyzed that which physiological factors play an essential role in this phenomenon and why it is less likely for humans to perceive yellowish or bluish observer metamers of white

Factors Affecting Clergy-Psychologist Referral Patterns

Recent research on clergy-psychologist collaboration has resulted in helpful principles for clergy and psychologists working together, but very little is known about what specific characteristics in clergy are appealing to psychologists and vice versa. Two experimental survey studies are reported, both exploring characteristics that enhance or hinder collaboration. In Study 1, Southern Baptist pastors rated the likelihood of referring to a counselor who was identified as either a Biblical Counselor or a Christian Psychologist, and was identified as either being excellent in interpersonal skills or as using scripture and prayer in counseling. Pastors demonstrated a preference for counselors using scripture and prayer in counseling over those described as having excellent interpersonal skills. In Study 2, psychologist respondents rated the likelihood of referring to a clergyperson who was identified either as a Baptist or a Unitarian universalist, and was identified either as seminary trained or as having a doctoral degree from a prestigious divinity school. Psychologists demonstrated a preference for those with a doctoral degree. The weak effect sizes and comments offered on the surveys suggest that the individual relationship between clergy and psychologist is much more salient than particular demographic characteristics when considering the possibility of collaboration

Using suprathreshold color-difference ellipsoids to estimate any perceptual color-difference

[EN] Relating instrumentally measured to visually perceived colour-differences is one of the challenges of advanced colorimetry. Lately, the use of color difference formulas is becoming more important in the computer vision field as it is a key tool in advancing towards perceptual image processing and understanding. In the last decades, the study of contours of equal color-differences around certain color centers has been of special interest. In particular, the contour of threshold level difference that determines the just noticeable differences (JND) has been deeply studied and, as a result, a set of 19 different ellipsoids of suprathreshold color-difference is available in the literature. In this paper we study whether this set of ellipsoids could be used to compute any color difference in any region of the color space. To do so, we develop a fuzzy multi-ellipsoid model using the ellipsoids information along with two different metrics. We see that the performance of the two metrics vary significantly for very small, small, medium and large color differences. Therefore, we also study how to adapt two metric parameters to optimize performance. The obtained results outperform the currently CIE-recommended colordifference formula CIEDE2000.S. Morillas acknowledges the support of grants PRX16/00050 and PRX17/00384 (Ministerio de Educacion, Cultura y Deporte) and MTM2015-64373-13 (MINECO/FEDER, UE). The authors thank Dr. Manuel Melgosa, Dr. Luis Gomez-Robledo, Dr. Esther Sanabria-Codesal, Dr. Francisco Montserrat and Mr. Fu Jiang for providing useful materials, information and suggestions.Morillas, S.; Fairchild, MD. (2018). Using suprathreshold color-difference ellipsoids to estimate any perceptual color-difference. Journal of Visual Communication and Image Representation. 55:142-148. https://doi.org/10.1016/j.jvcir.2018.05.022S1421485

FDG-PET Quantification of Lung Inflammation with Image-Derived Blood Input Function in Mice

Dynamic FDG-PET imaging was used to study inflammation in lungs of mice following administration of a virulent strain of Klebsiella (K.) pneumoniae. Net whole-lung FDG influx constant (Ki) was determined in a compartment model using an image-derived blood input function. Methods. K. pneumoniae (~3 x 105 CFU) was intratracheally administered to six mice with 6 other mice serving as controls. Dynamic FDG-PET and X-Ray CT scans were acquired 24 hr after K. pneumoniae administration. The experimental lung time activity curves were fitted to a 3-compartment FDG model to obtain Ki. Following imaging, lungs were excised and immunohistochemistry analysis was done to assess the relative presence of neutrophils and macrophages. Results. Mean Ki for control and K. pneumoniae infected mice were (5.1 ± 1.2) ×10−3 versus (11.4 ± 2.0) ×10−3 min−1, respectively, revealing a 2.24 fold significant increase (P = 0.0003) in the rate of FDG uptake in the infected lung. Immunohistochemistry revealed that cellular lung infiltrate was almost exclusively neutrophils. Parametric Ki maps by Patlak analysis revealed heterogeneous inflammatory foci within infected lungs. Conclusion. The kinetics of FDG uptake in the lungs of mice can be noninvasively quantified by PET with a 3-compartment model approach based on an image-derived input function

Spectral Reflectance Reconstruction Using Fuzzy Logic System Training: Color Science Application

[EN] In this work, we address the problem of spectral reflectance recovery from both CIEXYZ and RGB values by means of a machine learning approach within the fuzzy logic framework, which constitutes the first application of fuzzy logic in these tasks. We train a fuzzy logic inference system using the Macbeth ColorChecker DC and we test its performance with a 130 sample target set made out of Artist's paints. As a result, we obtain a fuzzy logic inference system (FIS) that performs quite accurately. We have studied different parameter settings within the training to achieve a meaningful overfitting-free system. We compare the system performance against previous successful methods and we observe that both spectrally and colorimetrically our approach substantially outperforms these classical methods. In addition, from the FIS trained we extract the fuzzy rules that the system has learned, which provide insightful information about how the RGB/XYZ inputs are related to the outputs. That is to say that, once the system is trained, we extract the codified knowledge used to relate inputs and outputs. Thus, we are able to assign a physical and/or conceptual meaning to its performance that allows not only to understand the procedure applied by the system but also to acquire insight that in turn might lead to further improvements. In particular, we find that both trained systems use four reference spectral curves, with some similarities, that are combined in a non-linear way to predict spectral curves for other inputs. Notice that the possibility of being able to understand the method applied in the trained system is an interesting difference with respect to other 'black box' machine learning approaches such as the currently fashionable convolutional neural networks in which the downside is the impossibility to understand their ways of procedure. Another contribution of this work is to serve as an example of how, through the construction of a FIS, some knowledge relating inputs and outputs in ground truth datasets can be extracted so that an analogous strategy could be followed for other problems in color and spectral science.Samuel Morillas acknowledges the support of the Spanish Ministry of Science under grants PRX17/00384, PRX16/00050 and PID2019-107790RB-C22.Amiri, MM.; Garcia-Nieto, S.; Morillas, S.; Fairchild, MD. (2020). Spectral Reflectance Reconstruction Using Fuzzy Logic System Training: Color Science Application. Sensors. 20(17):1-18. https://doi.org/10.3390/s20174726S118201

Developmental cues and persistent neurogenic potential within an in vitro neural niche

<p>Abstract</p> <p>Background</p> <p>Neurogenesis, the production of neural cell-types from neural stem cells (NSCs), occurs during development as well as within select regions of the adult brain. NSCs in the adult subependymal zone (SEZ) exist in a well-categorized niche microenvironment established by surrounding cells and their molecular products. The components of this niche maintain the NSCs and their definitive properties, including the ability to self-renew and multipotency (neuronal and glial differentiation).</p> <p>Results</p> <p>We describe a model <it>in vitro </it>NSC niche, derived from embryonic stem cells, that produces many of the cells and products of the developing subventricular zone (SVZ) and adult SEZ NSC niche. We demonstrate a possible role for apoptosis and for components of the extracellular matrix in the maintenance of the NSC population within our niche cultures. We characterize expression of genes relevant to NSC self-renewal and the process of neurogenesis and compare these findings to gene expression produced by an established neural-induction protocol employing retinoic acid.</p> <p>Conclusions</p> <p>The <it>in vitro </it>NSC niche shows an identity that is distinct from the neurally induced embryonic cells that were used to derive it. Molecular and cellular components found in our <it>in vitro </it>NSC niche include NSCs, neural progeny, and ECM components and their receptors. Establishment of the <it>in vitro </it>NSC niche occurs in conjunction with apoptosis. Applications of this culture system range from studies of signaling events fundamental to niche formation and maintenance as well as development of unique NSC transplant platforms to treat disease or injury.</p

The Anthropocene is a prospective epoch/series, not a geological event

The Anthropocene defined as an epoch/series within the Geological Time Scale, and with an isochronous inception in the mid-20th century, would both utilize the rich array of stratigraphic signals associated with the Great Acceleration and align with Earth System science analysis from where the term Anthropocene originated. It would be stratigraphically robust and reflect the reality that our planet has far exceeded the range of natural variability for the Holocene Epoch/Series which it would terminate. An alternative, recently advanced, time-transgressive ‘geological event’ definition would decouple the Anthropocene from its stratigraphic characterisation and association with a major planetary perturbation. We find this proposed anthropogenic ‘event’ to be primarily an interdisciplinary concept in which historical, cultural and social processes and their global environmental impacts are all flexibly interpreted within a multi-scalar framework. It is very different from a stratigraphic-methods-based Anthropocene epoch/series designation, but as an anthropogenic phenomenon, if separately defined and differently named, might be usefully complementary to it