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PubMed1961

Taxonomically significant color reactions of Brevibacterium linens.

Grecz, Nicholas (University of Chicago, Chicago, Ill.), and Gail M. Dack. Taxonomically significant color reactions of Brevibacterium linens. J. Bacteriol. 82:241-246. 1961.-Brevibacterium linens was observed to give characteristic color reactions with certain bases and acids. An intensive carmine-red color appeared immediately after addition of a drop of 5 n sodium hydroxide, 5 n potassium hydroxide, and saturated barium hydroxide. A light carmine-red was given by lithium hydroxide, and a light orange-red with a milky suspension of calcium hydroxide. No discernible color change was given with weak bases such as ammonium hydroxide, aniline, and pyridine.A characteristic salmon-pink color was produced when B. linens was rubbed with a glass rod in a drop of glacial acetic acid or filter paper; a brick-red color was produced with aniline under these conditions. With syrupy phosphoric acid a green color appeared within 3 to 4 min which turned blue after approximately 3 hr. The blue color was stable for several days. On the basis of these color reactions, B. linens could be distinguished from other microorganisms possessing yellow-orange pigmentation, i.e., Staphylococcus aureus, Staphylococcus epidermidis, Micrococcus flavus, Micrococcus citreus, Mycobacterium phlei, Sarcina lutea. Therefore, these color changes may be used for the identification of B. linens. Original isolates of B. linens from cheese were tested by these spot reactions and all presumptive identifications could be subsequently confirmed by conventional methods. Blue and green colors appeared in all yellow-orange chromogens treated with sulfuric, perchloric, and hydrochloric acids and hence these colors were not specific for B. linens.

Brevibacterium↗

PubMed2003

Color sensitivity of cells responsive to complex stimuli in the temporal cortex.

The inferotemporal (IT) cortex of the monkey lies at the head of the ventral visual pathway and is known to mediate object recognition and discrimination. It is often assumed that color plays a minor role in the recognition of objects and faces because discrimination remains highly accurate with black-and-white images. Furthermore it has been suggested that for rapid presentation and reaction tasks, object classification may be based on a first wave of feedforward visual information, which is coarse and achromatic. The fine detail and color information follows later, allowing similar stimuli to be discriminated. To allow these theories to be tested, this study investigates whether the presence of color affects the response of IT neurons to complex stimuli, such as faces, and whether color information is delayed with respect to information about stimulus form in these cells. Color, achromatic, and false-color versions of effective stimuli were presented using a rapid serial visual presentation paradigm, and responses recorded from single cells in IT of the adult monkey. Achromatic images were found to evoke significantly reduced responses compared with color images in the majority of neurons (70%) tested. Differential activity for achromatic and colored stimuli was evident from response onset with no evidence to support the hypothesis that information about object color is delayed with respect to object form. A negative correlation (P < 0.01) was found between cell latency and color sensitivity, with the most color-sensitive cells tending to respond earliest. The results of this study suggest a strong role for color in familiar object recognition and provide no evidence to support the idea of a first wave of form processing in the ventral stream based on purely achromatic information.

Animals↗

PubMed1982

Is there a high concentration of color-selective cells in area V4 of monkey visual cortex?

1. Recordings were made from neurons located within the central-field representation of the V4 area of extrastriate visual cortex using a semichronic, nitrous-oxide preparation; the properties of 174 cells were examined in sufficient detail to permit their classification. Cyto- and myeloarchitectural studies confirmed the identification of the area. 2. Color-selective cells with either color-biased or color-opponent properties represented about 20% of the examined population. Their incidence was not significantly different from that of similar cells encountered in penetrations into the central-field representation of area V2. 3. Most color-selective cells had color-biased properties, responding best to wave-lengths shorter than 460 nm, or longer than 580 n, or both. No examples of "green-biased" cells were found. Some color-biased cells responded to photopically matched white light, while others did not. Very few cells showed overt color-opponent responses. The spectral sensitivity of color-selective cells was not unusually narrow. 4. Cells lacking color selectivity and responding equally well to chromatic and achromatic lights of equal photopic luminosity, were the most commonly encountered cell type in penetrations of different parts of the V4 area (56%). Other than color, these cells showed stimulus preferences like those of color-selective cells. 5. One-fourth of V4 cells could not be systematically driven with the various stimuli used. This finding is consistent with recent results of recordings from the prelunate gyrus of the behaving monkey suggesting that some V4 cells receive extraretinal signals. 6. Our results do not support recent claims that V4 is specialized in the detailed analysis of color information.

Animals↗

PubMed1990

Spectral sensitivities of elementary color-coded neurons in butterfly larva.

1. Response properties and spectral sensitivities of a functional class of medulla neurons that received dominant input from a single stemma in the swallowtail butterfly larva were examined with regard to neutral and chromatic backgrounds. 2. Eight types of neurons were dominated by a dichromatic stemma with blue and green receptors. Six showed specific color-opponent responses mediated by two receptors on different backgrounds; one showed strong color opponency because of fairly balanced antagonistic input on the neutral (dark and white) background; the other five usually had weak or concealed color opponency on a neutral background but became strongly color opponent when appropriate chromatic illumination was present on the background. The most complex neuron gave excitatory responses on a dark background, inhibitory responses on a white background, and color-opponent responses on a chromatic (yellow) background. 3. The remaining two types of neurons dominated by the dichromatic stemma showed non-color-opponent and broad action spectra ascribable to a synergistic effect of the two classes of photoreceptors. 4. All eight types of neurons dominated by a trichromatic stemma (with UV, blue, and green receptors) were color opponent. Five showed strong color-opponent responses with the mediation of the three classes of receptors or only two (UV and green) on a neutral background. The others revealed distinct color opponency in the presence of UV or green illumination on the background. 5. The larval medulla neurons described may form parallel, elementary color-coded channels in the medulla neuropile to combine the outputs of the different color receptors in a single visual unit (stemma) into specific color-opponent signals. They probably correspond to columnar relay neurons in the medulla of the adult insects with a compound eye.

Animals↗

PubMed2005

Variation in stomatopod (Gonodactylus smithii) color signal design associated with organismal condition and depth.

In interactions, many tropical stomatopod species display conspicuous colored body spots that can communicate information about the sender's state (e.g., sex, aggressiveness, etc.). Species inhabiting a variety of depths experience large differences in illumination spectrum and intensity due to filtering of light by water and its constituents. Stomatopod spectral sensitivity is known to vary phenotypically with changes in light environment (associated with depth) that potentially affects the detection of color signals. Animals collected at different depths also have different body coloration. This study examines how spectral differences in colored body spots vary with organismal condition and models the effects of changing body coloration, light environment, and spectral sensitivity on the detection of color signals in a gonodactyloid species, Gonodactylus smithii. Of the seven conspicuous color spots that were measured in G. smithii, three had spectral differences that correlated with sex, aggression, and female reproductive state. A model of color detection in G. smithii indicates that longer-wavelength spectral content was affected most by varying body coloration and light conditions. Most color signals were perceived similarly both by shallow- and by deep-adapted photoreceptor sets over a range of depths (1-13 m). Eye spot ('meral spot') color detection also was invariant over the same depth range in shallow- and deep-adapted, long-wavelength receptors, but deep-adapted receptors continued to maintain a consistent detection of these spots down to 18 meters. These results suggest that meral spot coloration may have evolved as a constant signal when viewed by conspecifics from various depths.

Adaptation, Physiological↗

PubMed2004

Color and size interactions in a real 3D object similarity task.

In the natural world, objects are characterized by a variety of attributes, including color and shape. The contributions of these two attributes to object recognition are typically studied independently of each other, yet they are likely to interact in natural tasks. Here we examine whether color and size (a component of shape) interact in a real three-dimensional (3D) object similarity task, using solid domelike objects whose distinct apparent surface colors are independently controlled via spatially restricted illumination from a data projector hidden to the observer. The novel experimental setup preserves natural cues to 3D shape from shading, binocular disparity, motion parallax, and surface texture cues, while also providing the flexibility and ease of computer control. Observers performed three distinct tasks: two unimodal discrimination tasks, and an object similarity task. Depending on the task, the observer was instructed to select the indicated alternative object which was "bigger than," "the same color as," or "most similar to" the designated reference object, all of which varied in both size and color between trials. For both unimodal discrimination tasks, discrimination thresholds for the tested attribute (e.g., color) were increased by differences in the secondary attribute (e.g., size), although this effect was more robust in the color task. For the unimodal size-discrimination task, the strongest effects of the secondary attribute (color) occurred as a perceptual bias, which we call the "saturation-size effect": Objects with more saturated colors appear larger than objects with less saturated colors. In the object similarity task, discrimination thresholds for color or size differences were significantly larger than in the unimodal discrimination tasks. We conclude that color and size interact in determining object similarity, and are effectively analyzed on a coarser scale, due to noise in the similarity estimates of the individual attributes, inter-attribute attentional interactions, or coarser coding of attributes at a "higher" level of object representation.

Adult↗

PubMed2001

The concentration of three anti-seizure medications in hair: the effects of hair color, controlling for dose and age.

BACKGROUND: This paper assess the relationship between the quantity of three anti-seizure medications in hair and the color of the analyzed hair, while controlling for the effects of dose, dose duration, and patient age for 140 clinical patients undergoing anti-seizure therapy. Three drugs are assessed: carbamazepine (40 patients), valproic acid (40 patients), and phenytoin (60 patients). The relationship between hair assay results, hair color, dose, dose duration, and age is modeled using an analysis of covariance. The covariance model posits the hair assay results as the dependent variable, the hair color as the qualitative categorical independent variable, and dose, dose duration, and age as covariates. The null hypothesis assessed is that there is a no relationship between hair color and the quantity of analyte determined by hair assay such that darker colored hair will demonstrate higher concentrations of analyte than lighter colored hair. RESULTS: The analysis reveals that there is a significant relationship between dose and concentration for all hair color categories independent of the other covariates or the categorical independent variable. CONCLUSION: There does not appear to be any relationship between carbamazepine concentration and hair color. There is a weak relationship between hair color and valproic acid concentration, which the data suggest may be mediated by age. There is a significant, moderate relationship between phenytoin concentration and hair color such that darker colored hair has greater concentration values than lighter colored hair.

Age Factors↗

PubMed2004

Interspecific and intraspecific views of color signals in the strawberry poison frog Dendrobates pumilio.

Poison frogs in the anuran family Dendrobatidae use bright colors on their bodies to advertise toxicity. The species Dendrobates pumilio Schmidt 1858, the strawberry poison frog, shows extreme polymorphism in color and pattern in Panama. It is known that females of D. pumilio preferentially choose mates of their own color morph. Nevertheless, potential predators must clearly see and recognize all color morphs if the aposematic signaling system is to function effectively. We examined the ability of conspecifics and a model predator to discriminate a diverse selection of D. pumilio colors from each other and from background colors. Microspectrophotometry of isolated rod and cone photoreceptors of D. pumilio revealed the presence of a trichromatic photopic visual system. A typical tetrachromatic bird system was used for the model predator. Reflectance spectra of frog and background colors were obtained, and discrimination among spectra in natural illuminants was mathematically modeled. The results revealed that both D. pumilio and the model predator discriminate most colors quite well, both from each other and from typical backgrounds, with the predator generally performing somewhat better than the conspecifics. Each color morph displayed at least one color signal that is highly visible against backgrounds to both visual systems. Our results indicate that the colors displayed by the various color morphs of D. pumilio are effective signals both to conspecifics and to a model predator.

Animals↗

PubMed2001

Color line search for illuminant estimation in real-world scenes.

The estimation of illuminant color is mandatory for many applications in the field of color image quantification. However, it is an unresolved problem if no additional heuristics or restrictive assumptions apply. Assuming uniformly colored and roundly shaped objects, Lee has presented a theory and a method for computing the scene-illuminant chromaticity from specular highlights [H. C. Lee, J. Opt. Soc. Am. A 3, 1694 (1986)]. However, Lee's method, called image path search, is less robust to noise and is limited in the handling of microtextured surfaces. We introduce a novel approach to estimate the color of a single illuminant for noisy and microtextured images, which frequently occur in real-world scenes. Using dichromatic regions of different colored surfaces, our approach, named color line search, reverses Lee's strategy of image path search. Reliable color lines are determined directly in the domain of the color diagrams by three steps. First, regions of interest are automatically detected around specular highlights, and local color diagrams are computed. Second, color lines are determined according to the dichromatic reflection model by Hough transform of the color diagrams. Third, a consistency check is applied by a corresponding path search in the image domain. Our method is evaluated on 40 natural images of fruit and vegetables. In comparison with those of Lee's method, accuracy and stability are substantially improved. In addition, the color line search approach can easily be extended to scenes of objects with macrotextured surfaces.

Algorithms↗

PubMed1990

Chromatic induction and brightness contrast: a relativistic color model.

It has been suggested that object colors in a colored environment are the result of combining in perception the (relative) brightness of each spectral component rather than of just mixing the spectral luminances. We tested this hypothesis with the following experiment: A pair of center-surround targets made of colored papers was illuminated with trichromatic white light. Two identical central color plates (test and match field, respectively) were surrounded by frames of different colors and thus looked different because of simultaneous color contrast. Observers were asked to match the colors by changing the illumination of the match field by means of a color-mixture projector (color match, CM). This color-matched reflectance was measured with a photometer, and its CIE coordinates were determined. We then illuminated the display with one of the three primaries that made up our trichromatic white light. The different reflectances of the different surrounds at each primary induced simultaneous brightness contrast. The brightnesses of the two central plates were therefore different. Observers were asked to change the intensity of the illumination of the match field at the respective primary so that it looked equally bright as the test field. This procedure was repeated for each primary (primary brightness match, PBM). Then the whole display except for the match field was illuminated with the trichromatic white as before, while the latter was illuminated with a trichromatic mixture consisting of the primaries at the intensities as set in the PBM experiment, and the CIE values were determined with the photometer. The CIE values of the match field after the CM and PBM procedures were nearly identical. This indicates that composite colors are composed in perception by combining the scaled (or relative) brightness of each spectral component and that this brightness scaling is largely restricted to interactions in the same spectral region. The results are compared with those of other models concerned with contrast colors as well as with neurophysiological data. Some limitations are mentioned.

Adult↗

PubMed2006

Seasonal pelage color change: news based on a South American rodent.

Mammalian seasonal molting and color change are known to be influenced by photoperiod changes. Calomys laucha, a South American rodent, exhibits seasonal pelage color change; however, unlike Northern hemisphere rodents, which present a gray or brown color during summer and a whitish color during winter, C. laucha pelage changes from an orange color during summer to a dark gray color during winter. Animals maintained for over a year in stationary photoperiod (LD 12:12h, 22 degrees C) presented orange pelage color during the summer corresponding month (January), and gray color during the winter corresponding month (July). Same age animals were evaluated during summer or winter months, and also showed different colors. Animals exposed for 12 weeks to summer or winter artificial conditions displayed color change, not according to the environmental conditions, as expected, but similar to that of animals maintained in stationary photoperiod. These results suggest that pelage color change in C. laucha is controlled by an endogenous circannual rhythm. The adaptive function of C. laucha color change is discussed.

Animals↗

PubMed2000

Japanese and Korean female students' evaluation of elderly people's clothing colors.

This study evaluated the clothing colors in the elderly. We took photos using the elderly as models, displayed them on a computer screen, and produced 75 colors of the clothing in the elderly using computer graphics. The 75 colors were evaluated by Japanese and Korean female students. We compared the ideal colors for and the colors actually worn by elderly people in Japan and Korea. Korean students tended to evaluate high value colors positively, while Japanese students tended to evaluate low value colors positively. When asked to choose the ideal clothing color for elderly people, the choices differed between the Korean student group and the Japanese student group. The images held concerning these colors also differed between the two groups. When selecting the ideal color to be worn by elderly people, Japanese students attached importance to taste, brilliance, functionality and comfort. On the other hand, Korean students attached importance to commonness and inactivity when selecting the ideal clothing color for elderly people. Thus, in the present study, the evaluation of the clothing colors for elderly people differed between Japanese and Korean students.

Aged↗

PubMed2000

Sex and skill differences in translation of English color words by Chinese students.

The present study investigated sex and skill differences in color-word translation by Chinese-speaking students in university English classes. A questionnaire was administered to estimate the correlation between subjects' performance and their color-related hobbies. To conceptualize the issue better, two more groups of correlated parameter (academic achievements plus demographic factors) were introduced in this research as well. 40 English majors (20 women, 20 men), ranging in education from level one to level four, were randomly drawn from a metropolitan university and tested in the experiments as subjects. These university students were asked to provide Chinese equivalents for a list of 33 elaborated English color terms chosen from a thesaurus by mapping on the 11 color-tone categories defined by basic color theory. The results confirm the findings in relevant studies that used native speakers as subjects by observing that (1) women possessed a richer color vocabulary both in their source language and in their target language, (2) women also provided more elaborated Chinese equivalents to the color words used as stimuli, and finally, (3) women showed a superiority in accuracy in this color-lexicon matching or translating task. As a whole, the effects of skill and age were not significant. A significant correlation was found between the learners' proficiency in English and performance in translation of color words, but this relationship was rather weak and only true for the men. Color-related hobbies did not significantly correlate with the color-decoding performance of these language learners. Neither did the demographic factors. Taken together, it is sensible to state that differences reported here were affected primarily by the sex of the learn er. conditionally by language proficiency, and presumably by the cognitive and perceptual sex differences as well. These findings further indicate that the process of color codability is a complicated but unstudied issue in language learning and that sex should be treated as an independent variable in this area of research.

Achievement↗

PubMed2002

Subjective and objective evaluation of veal lean color.

Because veal lean color continues to be a primary factor that determines veal carcass value and is typically assessed by subjective means, it is important to explore objective methods for color assessment. Objective and subjective evaluations of veal flank and breast lean color were compared as predictors of longissimus lean color at 24 h postmortem. One hundred fifty special-fed Holstein veal calves were Kosher-slaughtered with blood samples collected upon exsanguination and analyzed for hematocrit and hemoglobin content. Lean color was evaluated in the flank and breast at 0, 6, 12, and 24 h postmortem. Color of the longissimus was evaluated at 6 h, when possible, and at 24 h. A panel of three trained individuals used a 5-point color standard developed in the Netherlands to visually evaluate lean color. A Minolta Chromameter CR-300 was used to obtain L*, a*, and b* values. A plant employee assigned packer grades at slaughter. Temperature and pH were also measured at each time period. Hemoglobin was more highly correlated than hematocrit with colorimeter values. Hemoglobin levels correlated well with a* values of the flank at 0 h postmortem (r = 0.52) although the correlation declined at 24 h (r = 0.30). The correlation between packer grades and 24-h visual loin color was r = 0.41. Visual loin color at 24 h postmortem was selected as the predicted variable for regression analysis. Temperature and pH did not contribute significantly to any prediction equations. The equation using breast L*, a*, and b* values at 24 h postmortem to predict 24-h loin color gave a higher prediction coefficient (R2 = 0.44) than the corresponding equation using 0-h breast values (R2 = 0.28). Objective measurement of lean color may be useful in veal carcass grading because it is more precise than subjective methods and would allow for uniformity among processing plants.

Animals↗

PubMed1997

Color flow sonography in evaluating the resectability of periampullary and pancreatic tumors.

Over the past several years, we have developed a technique to assess the resectability of periampullary and pancreatic tumors using color flow sonography. This is a feasibility study to determine if sonography with color flow imaging can play a role in evaluating patients with periampullary and pancreatic tumors. This study comprises a retrospective analysis of 51 patients referred for color flow sonographic evaluation of resectability of periampullary and pancreatic neoplasm. Scanning was performed with state-of-the-art color flow sonographic systems. Vessels that were touched or occluded by tumor were categorized according to a Pancreatic Color Doppler Score. Other factors affecting resectability (metastasis, enlarged nodes) were recorded. Sonographic findings were correlated with surgical resectability and pathologic findings regarding tumor margins. The color flow study was complete technically (all index vessels visualized) in 49 of 51 patients (96%). In all, 643 of 647 vessels (99.4%) were imaged. Forty-five patients had sufficient surgical, pathologic, or clinical proof to be included in the resectability analysis. All 18 patients with circumferential tumor or vascular occlusion (Pancreatic Color Doppler Score 4 and 5) were found to have unresectable disease. All 10 patients in whom tumor did not touch (Pancreatic Color Doppler Score 0) had negative margins. All 30 patients considered to have unresectable tumors sonographically could not be resected. Patients in this category had one or more of the following: positive pathologic margins, positive nodes, liver metastasis, or not clinically resectable. Six of 15 considered resectable sonographically (40%) were unresectable for cure. Surgeons believed that color flow sonography influenced management in 10 of 45 patients (22% overall). Color flow sonography, a painless, noninvasive, and relatively inexpensive examination, may be an effective screening tool to evaluate periampullary and pancreatic neoplasms for resectability. Our data show that color flow sonography can correctly predict unresectability of periampullary and pancreatic neoplasms. Any future evaluation of imaging and management of periampullary and pancreatic tumors should include color flow sonography.

Adenocarcinoma↗

PubMed2000

[The investigation of color selection of 4340 cases of ceramic restorations].

OBJECTIVE: To find color coordinates of Vita color tabs compare with Chinese natural teeth and summarize the skills of color matching. METHODS: We studied 15,836 ceramic restorations of 4340 cases from 138 clinics in 18 provinces throughout China and compared their shade with that of the adjacent natural teeth using the Vita shade guide which has 16 standard tooth colors. Statistical analyses was made by comparing aptness of Chinese teeth with Vita shade. RESULTS: We found that 64.47% of the restorations were matched by Vita A, 15.85% were matched by Vita B, and 19.68% were matched by Vita C and D. The arrangement of Vita 16 colors by using frequency was A2, A3, B2, A1, A3.5, C1, D2, D3, C2, B3, C3, B1, A4, D4, B4 and C4. The first five color matching tabs used most frequently covered 73.85% of the total, while the last four colors only covered 3.07%. It seemed that Vita color tabs could not match well with Chinese teeth. We found that the shade of natural teeth was closely related to sex. But there were no significant difference between tooth color and different areas. CONCLUSION: Tooth color is closely related to sex. The color of ceramic crowns in men are darker than that in women. We have evidences that there are clear differences in color distribution between Chinese natural teeth and Vita shade guide.

China↗

PubMed2006

Influence of different post core materials on the color of Empress 2 full ceramic crowns.

BACKGROUND: For esthetic consideration, dentin color post core materials were normally used for all-ceramic crown restorations. However, in some cases, clinicians have to consider combining a full ceramic crown with a metal post core. Therefore, this experiment was conducted to test the esthetical possibility of applying cast metal post core in a full ceramic crown restoration. METHODS: The color of full ceramic crowns on gold and Nickel-Chrome post cores was compared with the color of the same crowns on tooth colored post cores. Different try-in pastes were used to imitate the influence of a composite cementation on the color of different restorative combinations. The majority of patients could not detect any color difference less than DeltaE 1.8 between the two ceramic samples. So, DeltaE 1.8 was taken as the objective evaluative criterion for the evaluation of color matching and patients' satisfaction. RESULTS: When the Empress 2 crown was combined with the gold alloy post core, the color of the resulting material was similar to that of a glass fiber reinforced resin post core (DeltaE = 0.3). The gold alloy post core and the try-in paste did not show a perceptible color change in the full ceramic crowns, which indicated that the color of the crowns might not be susceptible to change between lab and clinic as well as during the process of composite cementation. Without an opaque covering the Ni-Cr post core would cause an unacceptable color effect on the crown (DeltaE = 2.0), but with opaque covering, the color effect became more clinically satisfactory (DeltaE = 1.8). CONCLUSIONS: It may be possible to apply a gold alloy post core in the Empress 2 full ceramic crown restoration when necessary. If a non-extractible Ni-Cr post core exists in the root canal, it might be possible to restore the tooth with an Empress 2 crown after covering the labial surface of the core with one layer of opaque resin cement.

Ceramics↗

PubMed1995

[Congenital color vision deficiencies as a social problem].

Color vision standards for various occupations and schools have been greatly eased recently. However, if the trend is unaccompanied with proper advice for color defective persons, there is a risk of accidents such as occurred in the past when color vision standards had not been introduced, because the color vision defect is unchanged. In this context, the history of color vision standards and the color confusion by color defective persons in their daily life were reviewed. The collected data together with pathophysiological characteristics of defective color vision suggest that at least the following measures are necessary from a practical point of view: (1) By education and awareness, color defective persons can avoid errors in color in most cases. Therefore, ophthalmologists should inform them of their defects in childhood and give instructions on how to compensate for their disadvantages. (2) In public and occupational situations, all the information conveyed by color should include lettering or other forms of redundancy for the convenience of color defective persons.

Color Vision Defects↗