1,722,191 research outputs found
Artist’s colour rendering of HDR scenes in 3-D Mondrian colour-constancy experiments
No full textThe presentation provides an update on ongoing research using three-dimensional Colour Mondrians. Two still life arrangements comprising hand-painted coloured blocks of 11 different colours were subjected to two different lighting conditions of a nearly uniform light and directed spotlights. The three-dimensional nature of these test targets adds shadows and multiple reflections, not found in flat Mondrian targets. Working from exactly the same pair of scenes, an author painted them using watercolour inks and paints to recreate both LDR and HDR Mondrians on paper. This provided us with a second set of appearance measurements of both scenes. Here we measured appearances by measuring reflectances of the artist's rendering. Land's Colour Mondrian extended colour constancy from a pixel to a complex scene. Since it used a planar array in uniform illumination, it did not measure the appearances of real life 3-D scenes in non-uniform illumination. The experiments in this paper, by simultaneously studying LDR and HDR renditions of the same array of reflectances, extend Land's Mondrian towards real scenes in non-uniform illumination. The results show that the appearances of many areas in complex scenes do not correlate with reflectance
Colour appearance and colour rendering of HDR scenes: an experiment
No full textIn order to gain a deeper understanding of the appearance of coloured objects in a three-dimensional scene, the research introduces a multidisciplinary experimental approach. The experiment employed two identical 3-D Mondrians, which were viewed and compared side by side. Each scene was subjected to different lighting conditions. First, we used an illumination cube to diffuse the light and illuminate all the objects from each direction. This produced a low-dynamicrange (LDR) image of the 3-D Mondrian scene. Second, in order to make a high-dynamic range (HDR) image of the same objects, we used a directional 150W spotlight and an array of WLEDs assembled in a flashlight. The scenes were significant as each contained exactly the same three-dimensional painted colour blocks that were arranged in the same position in the still life. The blocks comprised 6 hue colours and 5 tones from white to black. Participants from the CREATE project were asked to consider the change in the appearance of a selection of colours according to lightness, hue, and chroma, and to rate how the change in illumination affected appearance. We measured the light coming to the eye from still-life surfaces with a colorimeter (Yxy). We captured the scene radiance using multiple exposures with a number of different cameras. We have begun a programme of digital image processing of these scene capture methods. This multi-disciplinary programme continues until 2010, so this paper is an interim report on the initial phases and a description of the ongoing project
A study on the equivalence of controlled and uncontrolled visual experiments
No full textVisual experiments, if performed in a traditional way, require asking participants to go to a laboratory, where displays are calibrated and illumination conditions are set in a convenient way. In recent years there has been an increasing interest in performing the experiments "out of the lab", with the aim of reducing costs, increasing the number of participants, and differentiating the population. The equivalence of the response of visual experiments performed in controlled and uncontrolled contexts is an open question which calls for research. In this work we aim at analyzing more deeply the equivalence between "controlled" and "uncontrolled" that we found in a previous study of the authors on the comparison of visual preferences for printed images. In particular, we are interested in understanding if, and to what degree, the uncontrolled experiments require actually more participants in order to average out the effects of the many uncontrolled parameters which may affects the response. In addition we aim at exploring the relationship, if any, between our previous conclusions and the difference in the attributes of the images for which the observers were asked to express their preference
Knowledge exchange in the CREATE project: Colour Research for European Advanced Technology Employment
No full textThe presentation will review a four-year European funded project CREATE (Colour Research for European Advanced Technology Employment), which was established in 2006. The group came together to promote and exchange research and knowledge through a series of conferences and training courses to researchers working in Europe who were in the early stages of their career. The long-term objective was to address a broad range of themes in colour and to develop with artists, designers, technologists and scientists a cross disciplinary approach to improving colour communication and education and to provide a forum for dialogue between different fields. Now at the end of the funding programme, this paper will highlight some of the key milestones of the project. Moreover, having completed a supplementary workshop event in October 2010, researchers considered new themes for the future
Colore e colorimetria : contributi multidisciplinari : atti della terza conferenza nazionale del Gruppo del Colore(INRIM, Torino, 24-26 ottobre 2007)- vol. III
No full textSpatial color algorithms: Milano retinex and NASA retinex
No full textThe Retinex theory of Edwin Land proposed a model of human color vision based on color perception experiments. The original Retinex algorithm, by Land and McCann, is capable of performing color correction and contrast enhancement of images, with some limitations regarding overexposed pictures and visual artifacts stemming from its implementation based on one dimensional paths. By replacing these paths by two dimensional kernels while maintaining all the basic tenets of the theory, another Retinex algorithm was obtained which does not produce artifacts and that can be extended into a variational formulation allowing to handle naturally both over and underexposed images. Furthermore, this variational formulation linked Retinex with histogram equalization in image processing and with efficiency of representation and lightness induction in visual neuroscience. This workshop aims to provide the attendants with a novel look at the Retinex theory of color vision, seeing its contributions in a different light and showing the potential for applications to problems in image processing and computer graphics such as color constancy, contrast enhancement, haze removal, tone mapping of high dynamic range images, gamut reduction and gamut extension for cinema, and color transfer
Colore e colorimetria : contributi multidisciplinari : atti della seconda conferenza nazionale del Gruppo del Colore(Università Milano Bicocca, 20-22 settembre 2006)- vol. II
No full textWhat a bad signal from this strange device
No full textWe are acquainted to a description of the eye as a good camera with clearly determined optical and spectral properties. Reality is not exactly like that. This presentation aims at reviewing the many peculiar characteristics that sometime are not considered in the process of modeling our human vision system. One can be tempted of simplifying or of considering our vision system as a black box that we can describe from a top-down point of view, following the habit of using more engineering than biological descriptions. This talk want to suggest that within the unusual property of our eye it can be hidden the key of interpretation of the inner mechanisms of our vision
Alternative Methods for Digital Color Restoration
No full textModern cinema has several technical standards and tools that aims at reproducing it through different devices and through time. This is not the case of the analog cinema from the past, even if recent.
When someone has to face the restoration of an aged film, usually no color reference is available. Even in the rare case of having some information about film characteristics, the film aging depends on so many parameters, like e.g. humidity and temperature of conservation, that no reliable model of the color fading can be used. As a consequence, we cannot properly use standard color management tools in the restoration pipeline.
What is done actually is restoring the frame by visual inspection, as main criterion of assessing the final results. This means that we operate in a “subjective way”. Thus, the restoration process “simulates” what we suppose could have been the original color. Then this is viewed in a new (modern) projection environment, in terms of gamut and overall balance and contrast.
Starting from these considerations, the talk will present an alternative approach for color and contrast processing in the digital restoration pipeline, able to lower the amount of supervision time required
When color meets computer vision color in computer vision: fundamentals and applications. By TheoGevers, ArjanGijsenij, Joost van deWeijer, Jan-MarkGeusebroek, Hoboken, NJ: Wiley, 2012, Wiley-IS&T Series in Imaging Science and Technology, ISBN: : 978-0-470-89084-4, 384 p
No full text- …
