We present a unifying framework in which "object-independent" modes of variation are learned from continuous-time data such as video sequences. These modes of variation can be used as "generators" to produce a manifold of images of a new object from a single example of that object. We develop the framework in the context of a well-known example: analyzing the modes of spatial deformations of a scene under camera movement. Our method learns a close approximation to the standard affine deformations that are expected from the geometry of the situation, and does so in a completely unsupervised (i.e. ignorant of the geometry of the situation) fashion. We stress that it is learning a "parameterization", not just the parameter values, of the data. We then demonstrate how we have used the same framework to derive a novel data-driven model of joint color change in images due to common lighting variations. The model is superior to previous models of color change in describing non-linear color changes due to lighting.

Thesis (M.S.)--Ohio State University, 1984. / Includes bibliographical references (leaves 48-52). Available online via OhioLINK's ETD Center

Males of the Mexican lizard Sceloporus minor (Phrynosomatidae) exhibit striking variation in dorsal coloration, both within and among populations, which may have arisen by sexual selection. The possible significance of this trait was investigated through a combination of observational and experimental approaches. This research revealed that males in one population (La Manzana) in NW Hidalgo exhibit three discrete color morphs (blue, yellow, red) each characterized by morphological, physiological and behavioral differences. Furthermore, these morphs can be identified by an objective approach to color assessment (spectroradiometry). In addition, males in a second population (Escalerillas) from SE San Luis Potosí were also found to occur in at least two color morphs (yellow and red), suggesting that color polymorphism may be general in this species. The hypothesis of sensory exploitation by male contest competition was tested for S. minor from Escalerillas; however, no support for this hypothesis was found. Overall, results from this study are consistent with the hypothesis of alternative reproductive tactics in S. minor.

Color has a large impact on our psychological and physiological responses. This study examines the value of color as a component in a healing environment for pediatric patient rooms by measuring color preferences among healthy children, pediatric patients, and design professionals. Environmental satisfaction is a significant mediator between the physical environment and children’s health. Previous color preference studies have typically been done with small color chips or papers, which are very different from seeing a color applied on wall surfaces. A simulation method allowed for investigating the value of color in real contexts and controlling confounding variables. The findings of this study demonstrated that blue and green are the most preferred, and white the least preferred color, by both children and design professionals. Children’s gender differences were found in that boys prefer red and purple less than girls. Pediatric patients reported lower preference scores for yellow than did healthy children. These findings lead to color application guidelines for designers to understand color more and eventually to create better environments for children and their families.

Melanophores are dark brown pigment cells located in the skin of fish, amphibia, reptiles, and many invertebrates. The color of the animal can change via rearrangement of pigment granules, melanosomes, in the cells. The dark melanophores can either hide colorful cells so that the animal appears dark, or let through colors from underneath. The animal regulates its colors and patterns via communicating nerve cells and hormones in the blood stream. It is nowadays well established that melatonin-stimulation of melanophores results in aggregation of melanosomes to the cell center and that the evident outcome is more transparent cells. It has previously been shown that the activity of serine and threonine kinases as well as phosphatases regulates the distribution of melanosomes in the cells. We wanted to study if tyrosine phosphorylations were involved in the regulation of melanosome aggregation. Melatonin-stimulated signaling in the African clawed frog, Xenopus laevis, melanophores was examined. Melansome aggregation was accompanied by tyrosine phosphorylation as shown by immunoblots. Inhibition of tyrosine phosphorylation reduced melanosome aggregation by melatonin, and the phosphorylation most likely regulated pigment aggregation. Tyrosine phosphorylation of the protein was mediated via a Gi/o protein coupled receptor, probably the melatonin receptor Mel1c. The phosphorylation was most likely not a result of the classical Gi/o protein pathway, as Src-kinase and mitogen-activated protein kinase seemed required for phosphorylation and melanosome aggregation. Two candidates for the phosphorylated protein were presented, talin and β-spectrin. The possible involvement of nitric oxide in melanosome aggregation by melatonin was investigated. Nitric oxide appeared to be necessary for melanosome aggregation. The effect of nitric oxide synthase inhibition on melanosome aggregation was not mediated via changes in the tyrosine-phosphorylated protein. We speculated that nitric oxide could affect melanosome distribution via modifications of the actin cytoskeleton. The use of recombinant melanophores as a biosensor has also been examined. A human G protein coupled receptor, opioid receptor 3, was inserted into melanophores by electroporation. The transfected melanophores responded dose-dependently to opioids and an inhibitor of opioid receptors reduced the aggregation response. Future melanophore biosensors migh detect a variety of substances, such as narcotics, pheromones, odors, and tastes.

This dissertation investigates the cultural connections made between race and color in works of fiction from the Victorian and Edwardian era, particularly how authors who are also artists invent fantastically colored characters who are purple, blue, red, and yellow to rewrite (and sometimes reclaim) difference in their fiction. These strange and eccentric characters include the purple madwoman in Charlotte Brontë’s Jane Eyre (1847), the blue gentleman from Wilkie Collins’s Poor Miss Finch (1872), the red peddler in Thomas Hardy’s The Return of the Native (1878), and the little yellow girls of Arthur Conan Doyle’s “The Yellow Face” (1893) and Frances Hodgson Burnett’s The Secret Garden (1911). These fictional texts serve as a point of access into the cultural meanings of color in the nineteenth century and are situated at the intersection of Victorian discourses on the visual arts and race science. The second half of the nineteenth century constitutes a significant moment in the history of color: the rapid development of new color technologies helps to trigger the upheavals of the first avant-garde artistic movements and a reassessment of coloring’s prestige in the art academies. At the same time, race science appropriates color, using it as a criterion for classification in the establishment of global racial hierarchies. By imagining what it would be like to change one’s skin color, these artist-authors employ the aesthetic realm of color to explore the nature of human difference and alterity. In doing so, some of them are able to successfully formulate their own challenges to nineteenth-century racial discourse.

<p>The dissertation work discussed here focuses on the behavioral and physiological aspects of visual sexual signaling in the blue crab, <italic>Callinectes sapidus</italic>. The blue crab has a pair of apposition compound eyes that are relatively acute (1.5 &deg; resolution) for an arthropod. The eyes have two photopigments sensitive to blue (&lambda;_max = 440 nm) and green (&lambda; _max=500 nm) light, allowing for simple color vision. Visual cues and signals are used during antagonistic and sexual communication and primarily involve claw-waving motions. A primary feature of the blue crab morphology is its sexually dimorphic claw coloration; males have blue and white claws and females have red claws. However, despite the potential for interesting color signaling, visual cues have typically been considered non-important, particularly in sexual communication where chemical cues have dominated blue crab signaling studies. </p><p>In a series of experiments designed to simultaneously test the role of visual cues in mating behavior and blue crab color vision, I tested males' responses to photographs of females with differently colored claws. I found that photographs of females elicited male courting behaviors. I also found that males preferred females with red claws over those with white or isoluminant (i.e. matched brightness) gray claws. The discrimination of red from isoluminant grey showed the use of color vision in male mate choice. </p><p>In natural populations, the claws of sexually mature females vary from light orange to deep red. To determine males' abilities discriminate between similar colors, I tested male color preferences for red against several shades of orange varying in brightness. Overall, males showed an innate preference for red-clawed females over those with variations of orange claws. However, in tests between red and orange shades similar in both brightness and hue, male blue crabs did not show a distinct preference, suggesting that males are either not able or not motivated to discriminate between these shades. Further, my results suggest that male blue crabs may use a mixture of chromatic and achromatic cues to discriminate between long-wavelength colors.</p><p>After confirming the use of color in mate choice, I focused on the role of claw color in intraspecific communication. To quantify claw coloration, I measured spectral reflectance of claws of a blue crab population in North Carolina. In both sexes, the color of the claw varied with reproductive maturity and may act as a cue of reproductive readiness. Additionally, there was individual variation in claw color which could indicate individual quality. I have modeled the appearance of claw coloration to the blue crab eye and found that these color differences are visible to the blue crab eye and potentially signal gender, reproductive readiness, and/or individual quality. </p><p>After investigating male mate choice, I began investigating visual aspects of female mating behavior. In the blue crab, like many crustaceans, courtship occurs during the female molting cycle and copulation takes place after the female has shed her exoskeleton. In crustaceans and other arthropods with compound eyes, the corneal lens of each facet is part of the exoskeleton and thus shed during molting. I used optomotor assays to evaluate the impact of molting on visual acuity (as measured by the minimum resolvable angle <italic> &alpha _min</italic>) in the female blue crab. I found that visual acuity decreases substantially in the days prior to molting and is gradually recovered after molting. Prior to molting,<italic> &alpha_min </italic>was 1.8 &deg;, a value approximating the best possible acuity in this species. In the 24 hours before molting, <italic> &alpha _min</italic>increased to a median of 15.0 &deg; (N=12), an eight-fold drop in visual acuity. Six days after molting, <italic> &alpha _min</italic>returned to the pre-molting value. Micrographs of <italic>C. sapidus </italic> eyes showed that a gap between the corneal lens and the crystalline cone appeared approximately five days prior to shedding and increased in width the process progressed. This separation was likely responsible for the loss of visual acuity observed in behavioral tests. Since mating is limited to the female's pubertal molt, a reduction in acuity during this time may have an effect on the sensory cues used in female mate choice. These results may be broadly applicable to all arthropods that molt and have particular importance for crustaceans that molt multiple times in their lifetime or have mating cycles paired with molting.</p> / Dissertation

This thesis focuses on the oppositional and complimentary forces of light and shadows in the culture of Naples, Italy. Demonstrating, through photographs and the analysis of these photographs, how the light of Naples, a ‘northern’ light, and its resultant shadows echo (metaphorically and in reality) the light and shadows of the society, culture and history of Naples, Italy.

Aquesta tesi està orientada a la detecció i l’eliminació d’ombres en moviment. Les ombres es poden definir com una part de l’escena que no està directament il·luminada, pel fet que la font d’il·luminació es troba obstruïda per un o diversos objectes. Sovint, les ombres en moviment que es troben en imatges o en seqüències de vídeo són causa d’errors en l’anàlisi del comportament humà. Això es deu a que les ombres poden causar una degradació dels resultats dels algorismes de processament d’imatges aplicats a: detecció d’objectes, segmentació, vídeo vigilància o en propòsits similars. En aquesta tesi primer s’analitzen exhaustivament els mètodes de detecció d’ombres en moviment, i després amb l’objectiu de compensar les seves limitacions es proposa un nou mètode de detecció i eliminació d’aquest tipus d’ombres. El mètode proposat no fa servir informació a priori de l’escena, ni tampoc es restringeix a un tipus d’escena en concret. A més, el mètode proposat pot detectar tant ombres acromàtiques com també les cromàtiques, fins i tot quan hi ha camuflatge (és a dir, quan hi ha una forta similitud de color entre el foreground i l’ombra). Aquest mètode explota una propietat de constància local de color aconseguida a causa de la supressió de la reflectància en les regions amb ombres. Per detectar les regions amb ombres en una escena, els valors de la imatge del background són dividits pels valors de la imatge actual, tots dos en l’espai de color RGB. Al llarg de la tesi es demostra com aquesta divisió serà utilitzada per detectar segments amb gradients baixos i constants, que al seu torn s’utilitzen per distingir entre ombres i foregrounds. Els resultats experimentals duts a terme sobre base de dades públiques mostren un rendiment superior dels mètodes proposats en aquesta Tesi, comparat amb els mètodes actuals més sofisticats de detecci ó i eliminació d’ombres. A més els resultats demostren que el mètode proposat és robust i precís a l’hora detectar diferents tipus d’ombres en diferents tipus de vídeos. / This thesis is devoted to moving shadows detection and suppression. Shadows could be defined as the parts of the scene that are not directly illuminated by a light source due to obstructing object or objects. Often, moving shadows in images sequences are undesirable since they could cause degradation of the expected results during processing of images for object detection, segmentation, scene surveillance or similar purposes. In this thesis first moving shadow detection methods are exhaustively overviewed. Beside the mentioned methods from literature and to compensate their limitations a new moving shadow detection method is proposed. It requires no prior knowledge about the scene, nor is it restricted to assumptions about specific scene structures. Furthermore, the technique can detect both achromatic and chromatic shadows even in the presence of camouflage that occurs when foreground regions are very similar in color to shadowed regions. The method exploits local color constancy properties due to reflectance suppression over shadowed regions. To detect shadowed regions in a scene the values of the background image are divided by values of the current frame in the RGB color space. In the thesis how this luminance ratio can be used to identify segments with low gradient constancy is shown, which in turn distinguish shadows from foreground. Experimental results on a collection of publicly available datasets illustrate the superior performance of the proposed method compared with the most sophisticated state-of-the-art shadow detection algorithms. These results show that the proposed approach is robust and accurate over a broad range of shadow types and challenging video conditions.

Se trata de ver como el sistema de zonas de Ansel Adamas aplicado a la fotografía analógica en blanco y negro, se traslada al actual sistema digital en color. Como el mundo analógico se acaba reflejando en el actual mundo digital.