 |
 |
 |
 |
 |
 |
 |
| |
|
|
|
|
|
|
| [ Database= Inspec |
|
| Results= 195 records | |
|
] |
Record: 52
COPYRIGHT: Copyright 1997, IEE RECORD NO.: 5576651 INSPEC Abstract No: B9706-6140C-612; C9706-1250-278 AUTHOR: Takebe, K.; Nakauchi, S.; Usui, S. CORP SOURCE: Dept. of Inf. & Comput. Sci., Toyohashi Univ. of Technol., Japan TITLE: A computational model for color constancy in shadows SOURCE: WCNN '95. World Congress on Neural Networks. 1995 International Neural Network Society Annual Meeting, p. 3 vol. (xxxi+xvi+832+1001+273), 246-9 vol.1 PLACE OF PUBL: USA ISBN: 0805821252 LANGUAGE: English PUBLISHER: Lawrence Erlbaum Associates; Mahwah, NJ, USA SPONSOR ORG: Int. Neural Network Soc CONF TITLE: Proceedings of the World Congress on Neural Networks CONF LOCATION: Washington, DC, USA; 17-21 July 1995 YEAR: 1995 TREATMENT: T Theoretical or Mathematical RECORD TYPE: Conference Paper ABSTRACT: This article describes a computational model for color constancy in shadows which includes two visual modules for recovering both spatial-illuminance distribution and reflectances of object surfaces from the input scene. Each module has a line process which interprets whether a given edge is derived from reflectance edge or illuminance edge based on the prior knowledge of shadows such as brightness mainly changes at the boundary of a shadowed area. Simulation results, using Mondrian images, showed that the proposed model correctly detected shadow edge and illuminant colors, and successfully removed them from the input image. This suggests that it is necessary to recover both surface reflectance and spatial illuminance distribution to achieve color constancy in shadows (4 Refs.) DESCRIPTORS: brightness; edge detection; image colour analysis; image reconstruction; photoreflectance IDENTIFIERS: computational model; color constancy; shadows; spatial- illuminance distribution; reflectances; object surfaces; input scene; reflectance edge; illuminance edge; brightness; Mondrian images; shadow edge CLASS CODES: B6140C (Optical information, image and video signal processing); C1250 (Pattern recognition); C1260 (Information theory)Record: 53
COPYRIGHT: Copyright 1997, IEE RECORD NO.: 5573744 INSPEC Abstract No: A9712-8732N-001 AUTHOR: van Trigt, C. CORP SOURCE: Saturnus 8, Heeze, Netherlands TITLE: Visual system-response functions and estimating reflectance SOURCE: Journal of the Optical Society of America A (Optics, Image Science and Vision), vol.14, no.4, p. 741-55 ISSN: 0740-3232 CODEN: JOAOD6 PLACE OF PUBL: USA LANGUAGE: English PUBLISHER: Opt. Soc. America YEAR: April 1997 COPYRIGHT NO: 0740-3232/97/040741-15$10.00 TREATMENT: T Theoretical or Mathematical; X Experimental RECORD TYPE: Journal Paper ABSTRACT: The almost-illuminant-independent achromatic variable xi [J. Opt. Soc. Am A 11, 1003 (1994)] is supplemented by two achromatic variables, both almost illuminant-independent. The results are numerically verified and obtained by means of so-called (human) visual system-response functions, defined as those linear combinations of the color-matching functions that constitute the best possible approximations to delta functions. It is argued that they and not the cone sensitivities are basic to understanding the visual system as a color-constant signal detection system. The three variables solve the color-constancy problem and define a chromatic adaptation transform for blackbody radiators of temperature T. The generalization of the results to arbitrary well-behaved illuminants is discussed (38 Refs.) DESCRIPTORS: colour vision IDENTIFIERS: human visual system-response functions; almost-illuminant- independent achromatic variable; linear combinations; color- matching functions; cone sensitivities; color-constant signal detection system; color-constancy problem; chromatic adaptation transform; blackbody radiators; arbitrary well- behaved illuminants; reflectance CLASS CODES: A8732N (Colour vision: detection, adaptation and discrimination)Record: 54
COPYRIGHT: Copyright 1997, IEE RECORD NO.: 5554311 INSPEC Abstract No: B9705-6140C-417; C9705-1250-200 AUTHOR: Barnard, K.; Finlayson, G.; Funt, B. CORP SOURCE: Sch. of Comput. Sci., Simon Fraser Univ., Burnaby, BC, Canada TITLE: Color constancy for scenes with varying illumination SOURCE: Computer Vision and Image Understanding, vol.65, no.2, p. 311-21 ISSN: 1077-3142 CODEN: CVIUF4 PLACE OF PUBL: USA LANGUAGE: English PUBLISHER: Academic Press YEAR: Feb. 1997 COPYRIGHT NO: 1077-3142/97/$25.00 TREATMENT: P Practical; T Theoretical or Mathematical RECORD TYPE: Journal Paper ABSTRACT: We present an algorithm which uses information from both surface reflectance and illumination variation to solve for color constancy. Most color constancy algorithms assume that the illumination across a scene is constant, but this is very often not valid for red images. The method presented in this work identifies and removes the illumination variation, and in addition uses the variation to constrain the solution. The constraint is applied conjunctively to constraints found from surface reflectances. Thus the algorithm can provide good color constancy when there is sufficient variation in surface reflectances, or sufficient illumination variation, or a combination of both. We present the results of running the algorithm on several real scenes, and the results are very encouraging (19 Refs.) DESCRIPTORS: computer vision IDENTIFIERS: color constancy for scenes; varying illumination; surface reflectance; illumination variation; surface reflectances CLASS CODES: B6140C (Optical information, image and video signal processing); C1250 (Pattern recognition)Record: 55
COPYRIGHT: Copyright 1997, IEE RECORD NO.: 5521315 INSPEC Abstract No: A9708-8732N-002 AUTHOR: Ronchi, L.R.; Abbozzo Heuser, M. TITLE: Looking at colored glasses SOURCE: Atti della Fondazione Giorgio Ronchi, vol.51, no.5, p. 733-71 ISSN: 0015-606X CODEN: AFDGA2 PLACE OF PUBL: Italy LANGUAGE: English PUBLISHER: Fond. Giorgio Ronchi YEAR: Sept.-Oct. 1996 TREATMENT: X Experimental RECORD TYPE: Journal Paper ABSTRACT: It is known that, when placing a colored glass close to the eye, the environment appears colored at first, but soon thereafter a gradual change in appearance occurs, in the direction of "discounting the glass", one of the ingredients of perceptual constancy. On the other hand, when a colored glass (of a relatively small size) is placed at a given distance from the eye, the color is persistently perceived. Now, let the eye be adapted to a neutral field; then, as the gaze is shifted to a point on a window with stained glasses, changes in appearance occur, which may be interpreted in terms of focal adaptive effects. Probably, in the case of many stained glasses, one is faced with the recovery of transient desensitization induced in post-receptoral stages. The experiments described here, show that the transient levelling-off of extra-brightness covers a number of seconds. Therefore, it is sizable, leaving room for the appreciation of the related aesthetical and emotional consequences. The point the authors would like to stress is that the response strongly depends on the spatial patterning of the observed detail. It renders difficult an accurate prediction of the outcome of the set of involved spatio- temporal chromatic interactions. One is faced with a sort of "Mondrian display", where moreover the presence of heavy metal interglass borders favours the discrimination, by calling into play the "gap effect" (15 Refs.) DESCRIPTORS: colour vision; visual perception IDENTIFIERS: colored glasses; visual appearance; perceptual constancy; focal adaptive effects; transient desensitization; post- receptoral stages; extra brightness; Mondrian display; heavy metal interglass borders; gap effect; spatial patterning; neutral field adaptation; appearance changes CLASS CODES: A8732N (Colour vision: detection, adaptation and discrimination); A8732S (Psychophysics of vision, visual perception, binocular vision)Record: 56
COPYRIGHT: Copyright 1997, IEE RECORD NO.: 5518236 INSPEC Abstract No: A9708-8732S-010; B9704-6140C- 325; C9704-5260B-214 AUTHOR: Jobson, D.J.; Rahman, Z.; Woodell, G.A. CORP SOURCE: NASA Langley Res. Center, Hampton, VA, USA TITLE: Properties and performance of a center/surround retinex SOURCE: IEEE Transactions on Image Processing, vol.6, no.3, p. 451-62 ISSN: 1057-7149 CODEN: IIPRE4 PLACE OF PUBL: USA LANGUAGE: English PUBLISHER: IEEE YEAR: March 1997 COPYRIGHT NO: 1057-7149/97/$10.00 TREATMENT: T Theoretical or Mathematical; X Experimental RECORD TYPE: Journal Paper ABSTRACT: The last version of Land's (1986) retinex model for human vision's lightness and color constancy has been implemented and tested in image processing experiments. Previous research has established the mathematical foundations of Land's retinex but has not subjected his lightness theory to extensive image processing experiments. We have sought to define a practical implementation of the retinex without particular concern for its validity as a model for human lightness and color perception. We describe the trade-off between rendition and dynamic range compression that is governed by the surround space constant. Further, unlike previous results, we find that the placement of the logarithmic function is important and produces best results when placed after the surround formation. Also unlike previous results, we find the best rendition for a "canonical" gain/offset applied after the retinex operation. Various functional forms for the retinex surround are evaluated, and a Gaussian form is found to perform better than the inverse square suggested by Land. Images that violate the gray world assumptions (implicit to this retinex) are investigated to provide insight into cases where this retinex fails to produce a good rendition (15 Refs.) DESCRIPTORS: colour vision; data compression; eye; Gaussian processes; image colour analysis; visual perception IDENTIFIERS: center/surround retinex; human color perception; human vision lightness; human color constancy; image processing experiments; lightness theory; Land's retinex model; rendition; dynamic range compression; surround space constant; logarithmic function; surround formation; canonical gain/offset; Gaussian form; inverse square; gray world assumptions CLASS CODES: A8732S (Psychophysics of vision, visual perception, binocular vision); B6140C (Optical information, image and video signal processing); C5260B (Computer vision and image processing techniques)Record: 60
COPYRIGHT: Copyright 1997, IEE RECORD NO.: 5461366 INSPEC Abstract No: A9703-8732S-023; C9702-7330-098 AUTHOR: Takebe, K.; Nakauchi, S.; Usui, S. CORP SOURCE: Toyohashi Univ. of Technol., Japan TITLE: A computational model for color constancy by separating reflectance and illuminant edges within a scene SOURCE: Neural Networks, vol.9, no.8, p. 1405-15 ISSN: 0893-6080 CODEN: NNETEB PLACE OF PUBL: USA LANGUAGE: English PUBLISHER: Elsevier YEAR: Nov. 1996 COPYRIGHT NO: 0893-6080/96/$15.00+.00 TREATMENT: P Practical RECORD TYPE: Journal Paper ABSTRACT: Several psychophysical experiments have revealed that color constancy exists even in shadowed scenes where the spatial power distribution of the illuminant has abrupt step changes, while previous models for color constancy fail to distinguish shadows and reflectance changes. The article addresses this problem and proposes a computational model for color constancy which separates reflectance and illuminant edges by two modules recovering both the spatial power distribution of the illuminant and surface reflectances of an object from an input scene. Each module has a line process which interprets whether a given edge is derived from a reflectance or illuminant change based on prior knowledge of shadows, it is mainly luminance that changes at the boundary of a shadowed area. Simulation results show that the proposed model correctly detects reflectance and illuminant edges and illuminant colours, and successfully removes the illuminant from the input scene. This suggests that recovering both surface reflectance and the spatial power distribution of the illuminant is one of the possible ways to achieve color constancy in shadows (21 Refs.) DESCRIPTORS: biology computing; brightness; colour vision; digital simulation; reflectivity; visual perception IDENTIFIERS: computational model; color constancy; illuminant edges; psychophysical experiments; shadowed scenes; spatial power distribution; abrupt step changes; reflectance changes; input scene; line process; illuminant change; prior knowledge; shadows; surface reflectance CLASS CODES: A8732S (Psychophysics of vision, visual perception, binocular vision); A8732N (Colour vision: detection, adaptation and discrimination); A8732Q (Scales for light and colour detection in vision); C7330 (Biology and medical computing); C6185 (Simulation techniques)Record: 62
COPYRIGHT: Copyright 1996, IEE RECORD NO.: 5421340 INSPEC Abstract No: B9612-6140C-301; C9612-1250-172 AUTHOR: Finlayson, G.D. CORP SOURCE: Dept. of Comput. Sci., York Univ., UK TITLE: Color in perspective SOURCE: IEEE Transactions on Pattern Analysis and Machine Intelligence, vol.18, no.10, p. 1034-8 ISSN: 0162-8828 CODEN: ITPIDJ PLACE OF PUBL: USA LANGUAGE: English PUBLISHER: IEEE Comput. Soc YEAR: Oct. 1996 COPYRIGHT NO: 0162-8828/96/$05.00 TREATMENT: T Theoretical or Mathematical RECORD TYPE: Journal Paper ABSTRACT: Simple constraints on the sets of possible surface reflectance and illuminants are exploited in a new color constancy algorithm that builds upon Forsyth's (1990) theory of color constancy. Forsyth's method invokes the constraint that the surface colors under a canonical illuminant all fall within an established maximal convex gamut of possible colors. However, the method works only when restrictive conditions are imposed on the world: the illumination must be uniform, the surfaces must be planar, and there can be no specularities. To overcome these restrictions, we modify Forsyth's algorithm so that it works with the colors under a perspective projection (in a chromaticity space). The new algorithm working in perspective is simpler than Forsyth's method and more importantly the restrictions on the illuminant, surface shape and specularities can be relaxed. The algorithm is then extended to include a maximal gamut constraint on a set of illuminants that is analogous to the gamut constraint on surface colors. Tests on real images show that the algorithm provides good color constancy (13 Refs.) DESCRIPTORS: computer vision; image colour analysis; lighting; reflectivity; spectral analysis IDENTIFIERS: surface reflectance; illuminants; color constancy; Forsyth theory; surface colors; chromaticity space; gamut mapping; image colors; camera response CLASS CODES: B6140C (Optical information, image and video signal processing); C1250 (Pattern recognition); C5260B (Computer vision and image processing techniques)Record: 65
COPYRIGHT: Copyright 1996, IEE RECORD NO.: 5385820 INSPEC Abstract No: A9621-8732N-004; C9611-1290L-042 AUTHOR: Glaria-Bengoechea, A.; Mpodozis-Marin, J.; Jonas-Zuniga, R.; Leiva, A.B. CORP SOURCE: Dept. of Physiol., Valparaiso Univ., Chile TITLE: RETINET: a neural network for the psychophysics of color vision SOURCE: ICNN 96. The 1996 IEEE International Conference on Neural Networks (Cat. No.96CH35907), p. 4 vol. xxxiii+2275, 724-7 vol.2 PLACE OF PUBL: USA ISBN: 0780332105 LANGUAGE: English PUBLISHER: IEEE; New York, NY, USA CONF TITLE: Proceedings of International Conference on Neural Networks (ICNN'96) CONF LOCATION: Washington, DC, USA; 3-6 June 1996 YEAR: 1996 COPYRIGHT NO: 0 7803 3210 5/96/$4.00 TREATMENT: T Theoretical or Mathematical RECORD TYPE: Conference Paper ABSTRACT: Psychophysics of color perception has demonstrated to be a complex phenomenon, because some illusionary perceptions raised questions about the view that it might be determined by the wavelength composition of the light spectra reflected into the retina. We review the phenomena of color constancy, color induction and colored shadows and develop a neural network with lateral interactions in its input layer, which implements these psychophysical phenomena suggesting a possible explanation for them. The model is based on a simplified neural architecture of the retina (20 Refs.) DESCRIPTORS: colour vision; eye; neural nets; neurophysiology; physiological models IDENTIFIERS: RETINET; neural network; psychophysics; color vision; color perception; wavelength composition; light spectra; retina; color constancy; color induction; colored shadows; lateral interactions; simplified neural architecture CLASS CODES: A8732N (Colour vision: detection, adaptation and discrimination); C1290L (Systems theory applications in biology and medicine); C1230D (Neural nets)Record: 66
COPYRIGHT: Copyright 1996, IEE RECORD NO.: 5374296 INSPEC Abstract No: A9620-8732N-003 AUTHOR: Lucassen, M.P.; Walraven, J. CORP SOURCE: Akzo Nobel Coatings b.v., Sassenheim, Netherlands TITLE: Color constancy under natural and artificial illumination SOURCE: Vision Research, vol.36, no.17, p. 2699-711 ISSN: 0042-6989 CODEN: VISRAM PLACE OF PUBL: UK LANGUAGE: English PUBLISHER: Elsevier YEAR: Sept. 1996 COPYRIGHT NO: 0042-6989/96/$15.00+0.00 TREATMENT: B Bibliography; X Experimental RECORD TYPE: Journal Paper ABSTRACT: Color constancy was studied under conditions simulating either natural or extremely artificial illumination. Four test illuminants were used: two broadband phases of daylight (correlated color temperatures 3000 and 25,000 K) and two spectrally impoverished metamers of these lights, each consisting of only two wavelengths. A computer controlled color monitor was used for reproducing the chromaticities and luminances of an array of Munsell color samples rendered under these illuminants. An asymmetric haploscopic matching paradigm was used in which the same stimulus pattern, either illuminated by one of the test illuminants, or by a standard broadband daylight (D/sub 65/), was alternately presented to the left and right eye. Subjects adjusted the RGB settings of the samples seen under D/sub 65/ (match condition), to match the appearance of the color samples seen under the test illuminant. The results show the expected failure of color constancy under two-wavelengths illumination, and approximate color constancy under natural illumination. Quantitative predictions of the results were made on the basis of two different models, a computational model for recovering surface reflectance, and a model that assumes the color response to be determined by cone-specific contrast and absolute level of stimulation (Lucassen and Walraven, 1993). The latter model was found to provide somewhat more accurate predictions, under all illuminant conditions (55 Refs.) DESCRIPTORS: colour vision; lighting IDENTIFIERS: color constancy; extremely artificial illumination; natural illumination; test illuminants; broadband phases; daylight; correlated color temperatures; spectrally impoverished metamers; computer controlled color monitor; chromaticities; luminances; Munsell color samples; asymmetric haploscopic matching paradigm; stimulus pattern; standard broadband daylight; two-wavelengths illumination; computational model; surface reflectance; cone-specific contrast CLASS CODES: A8732N (Colour vision: detection, adaptation and discrimination)Record: 67
COPYRIGHT: Copyright 1996, IEE RECORD NO.: 5359309 INSPEC Abstract No: A9619-8732N-003 AUTHOR: Kuriki, I.; Uchikawa, K. CORP SOURCE: Imaging Sci. & Eng. Lab., Tokyo Inst. of Technol., Yokohama, Japan TITLE: Limitations of surface-color and apparent-color constancy SOURCE: Journal of the Optical Society of America A (Optics, Image Science and Vision), vol.13, no.8, p. 1622-36 ISSN: 0740-3232 CODEN: JOAOD6 PLACE OF PUBL: USA LANGUAGE: English PUBLISHER: Opt. Soc. America YEAR: Aug. 1996 COPYRIGHT NO: 0740-3232/96/0801622-15$10.00 TREATMENT: T Theoretical or Mathematical RECORD TYPE: Journal Paper ABSTRACT: Color-constancy mechanisms have been studied and discussed in a number of investigations. However, there has been little attempt to reveal how color constancy deteriorates as the conditions for it become less than optimal. We carried out a series of asymmetric color-matching experiments, using two criteria: surface-color match and apparent-color match. With brief adaptation the degree of color constancy increased as chromatic cues were added in the surround. In the condition of black surround, the test stimuli appeared self-luminous, and chromaticities of the chosen matching stimuli were the same as the physical chromaticities of the test stimulus, indicating a total deficiency of color constancy. With 15 min of preadaptation to the illuminant, the surface-color matches showed almost perfect color constancy under illuminant change. In both adaptation conditions, the chromatic-shift of matches from what would be expected for perfect color constancy increased gradually between 1,700- and 30,000-K illuminant, as chromaticity of the illuminant departed from 6,500-K illuminant. Under 1,000- K illuminant the surface-color appearance became totally achromatic, and color constancy was completely lost. Our results show that, even with brief adaptation to the illuminant, the contribution of the surrounding stimulus is large enough to achieve a fair degree of color constancy, but complete adaptation to the illuminant helps to achieve almost perfect color constancy (24 Refs.) DESCRIPTORS: colorimetry; colour vision IDENTIFIERS: surface-color constancy; apparent-color constancy; asymmetric color-matching experiments; surface-color match; chromatic cues; black surround; self-luminous; physical chromaticities; color constancy; preadaptation; illuminant change; surface-color appearance; achromatic CLASS CODES: A8732N (Colour vision: detection, adaptation and discrimination); A8732Q (Scales for light and colour detection in vision); A0760D (Photometry and radiometry)Record: 70
COPYRIGHT: Copyright 1996, IEE RECORD NO.: 5287441 INSPEC Abstract No: C9607-5260B-371 AUTHOR: Praefcke, W.; Muller, F.; Illgner, K. CORP SOURCE: Inst. fur Elektrische Nachrichtentech., Tech. Hochschule Aachen, Germany TITLE: Illuminant-independent compression of color images SOURCE: Proc. SPIE - Int. Soc. Opt. Eng. (USA), Proceedings of the SPIE - The International Society for Optical Engineering, vol.2658, p. 287-96 ISSN: 0277-786X CODEN: PSISDG PLACE OF PUBL: USA LANGUAGE: English PUBLISHER: SPIE-Int. Soc. Opt. Eng SPONSOR ORG: SPIE; Soc. Imaging Sci. & Technol CONF TITLE: Color Imaging: Device-Independent Color, Color Hard Copy, and Graphic Arts CONF LOCATION: San Jose, CA, USA; 29 Jan.-1 Feb. 1996 YEAR: 1996 COPYRIGHT NO: 0 8194 2032 8/96/$6.00 TREATMENT: P Practical RECORD TYPE: Conference Paper; Journal Paper ABSTRACT: The coding of color images is usually confined to coding the color appearance for the illumination present at acquisition time. However, an exact reconstruction of a coded and transmitted document should produce the same color appearance as the original under variable illuminations. In this work we develop a representation of the necessary information to ensure such a color constancy. The only precondition is the absence of mutual illumination as a small but reasonable restriction to the type of illumination. The proposed image representation is developed to a complete image coder concept. Using this concept a hierarchical image description is achieved introducing a minimal color difference (5 Refs.) DESCRIPTORS: data compression; document image processing; image coding; image representation IDENTIFIERS: compression; color images; coding; reconstruction; image description; document imaging; color image coding; color constancy; illumination; metamerism CLASS CODES: C5260B (Computer vision and image processing techniques); C6130D (Document processing techniques); C1250 (Pattern recognition)Record: 72
COPYRIGHT: Copyright 1996, IEE RECORD NO.: 5243786 INSPEC Abstract No: B9606-6140C-009; C9606-5260B-007 AUTHOR: Petrov, A.P.; Antonova, G.N. CORP SOURCE: Res. Center, Kurchatov (I.V.) Inst. of Atomic Energy, Moscow, Russia TITLE: Resolving the color image irradiance equation SOURCE: Color Research & Application, vol.21, no.2, p. 97-103 ISSN: 0361-2317 CODEN: CREADU PLACE OF PUBL: USA LANGUAGE: English PUBLISHER: Wiley YEAR: April 1996 COPYRIGHT NO: 0361-2317/96/020097-07 TREATMENT: T Theoretical or Mathematical RECORD TYPE: Journal Paper ABSTRACT: The case of orthogonal projection of a smooth and piece-wise uniformly colored lambertian surface with complex color illumination is considered. The algorithm presented here is based on two equations: n.n=1 (the norm constancy condition) and Phi n.n=0 (the integrability condition, where Phi is a linear differential operator). Both equations hold over the whole image. Starting with the color-image irradiance equation (CIIE) for the trichromatic visual system, we infer an algebraic formulae for direct computation of the normal vector field n up to some rotation U, the same one for all the points in the region of color and illuminant constancy. The transition from the image to the normal field is performed in this stage of the algorithm with a symmetric and nonnegative matrix B, which is constant in the region. This property is used for labeling segments of the color image. The second step of the algorithm computes the rotation U mentioned above. This computation is based on CIIE and the integrability condition, but the way of finding a solution is quite different. An error-function dependent upon the rotation parameters is developed and some effective optimization algorithm is used for estimating the parameters (17 Refs.) DESCRIPTORS: computer vision; image colour analysis; image reconstruction; image segmentation; optical images; optimisation IDENTIFIERS: color image irradiance equation; orthogonal projection; uniformly colored lambertian surface; complex color illumination; norm constancy condition; integrability condition; linear differential operator; color-image irradiance equation; trichromatic visual system; algebraic formulae; direct computation; normal vector field; normal field; illuminant constancy; color image; error-function; rotation parameters; effective optimization algorithm CLASS CODES: B6140C (Optical information, image and video signal processing); C5260B (Computer vision and image processing techniques); C1250 (Pattern recognition)Record: 79
COPYRIGHT: Copyright 1996, IEE RECORD NO.: 5147088 INSPEC Abstract No: B9602-6140C-122; C9602-1250-072 AUTHOR: Buluswar, S.D.; Draper, B.A. CORP SOURCE: Dept. of Comput. Sci., Massachusetts Univ., Amherst, MA, USA TITLE: Non-parametric classification of pixels under varying outdoor illumination SOURCE: Proc. SPIE - Int. Soc. Opt. Eng. (USA), Proceedings of the SPIE - The International Society for Optical Engineering, vol.2353, p. 529-36 ISSN: 0277-786X CODEN: PSISDG PLACE OF PUBL: USA LANGUAGE: English PUBLISHER: SPIE-Int. Soc. Opt. Eng SPONSOR ORG: SPIE CONF TITLE: Intelligent Robots and Computer Vision XIII: Algorithms and Computer Vision CONF LOCATION: Boston, MA, USA; 31 Oct.-2 Nov. 1994 YEAR: 1994 COPYRIGHT NO: 0 8194 1688 6/94/$6.00 TREATMENT: X Experimental RECORD TYPE: Conference Paper; Journal Paper ABSTRACT: Using color for visual recognition of outdoors has proven to be a difficult problem, mainly due to varying illumination. Attempts to classify pixels or image patches in outdoor scenes often fail, partly because of the paucity of the data, and partly because the color shifts due to changes in illumination are not well modeled at random noise. Approaches which attempt to recover the "true color" of objects by calculating the color of the incident light (i.e. color-constancy approaches) appear to work in constrained environments, but are not yet applicable to outdoor scenes. We present a technique that uses training images of an object under daylight to learn the shift in color of an object. Our method uses multivariate decision trees for piecewise linear approximation of the region corresponding to the objects appearance in color space. We than classify pixels in outdoor scenes depending on whether they fall within this region, and group clusters of target pixels in to regions of interest for a model-based RSTA system. The techniques presented are demonstrated on a challenging tasks: recognizing camouflaged vehicles in outdoor military scenes (16 Refs.) DESCRIPTORS: approximation theory; brightness; computer vision; decision theory; image classification; image colour analysis; object recognition; trees (mathematics) IDENTIFIERS: nonparametric pixel classification; outdoor illumination; image patches; outdoor scene recognition; color shifts; color-constancy; multivariate decision trees; piecewise linear approximation; color space; group clusters; camouflaged vehicle recognition; chromatic variation; focus of attention CLASS CODES: B6140C (Optical information, image and video signal processing); B0250 (Combinatorial mathematics); B0290F (Interpolation and function approximation); B0240E (Game theory); C1250 (Pattern recognition); C5260B (Computer vision and image processing techniques); C1160 (Combinatorial mathematics); C1140E (Game theory); C4130 (Interpolation and function approximation)Record: 80
COPYRIGHT: Copyright 1995, IEE RECORD NO.: 5138100 INSPEC Abstract No: A9602-9385-059; B9601-7710-074; C9601-7840-113 AUTHOR: Wiemker, R. EDITOR: Hlavac, V.; Sara, R. CORP SOURCE: II. Inst. fur Experimentalphys., Hamburg Univ., Germany TITLE: The color constancy problem: an illumination invariant mapping approach SOURCE: Computer Analysis of Images and Patterns. 6th International Conference, CAIP'95. Proceedings, p. xviii+960, 950-5 PLACE OF PUBL: Germany ISBN: 3540602682 LANGUAGE: English PUBLISHER: Springer-Verlag; Berlin, Germany CONF TITLE: Proceedings of 6th International Conference on Computer Analysis of Images and Patterns CONF LOCATION: Prague, Czech Republic; 6-8 Sept. 1995 YEAR: 1995 TREATMENT: P Practical; T Theoretical or Mathematical RECORD TYPE: Conference Paper ABSTRACT: A novel approach is suggested to the color constancy problem for multispectral imagery. The author's approach is based on a dichromatic illumination model and filters out all spectral information which possibly stems from the illumination rather than from the reflectance of a given surface. Instead of recovering the reflectance signal, the suggested mapping produces a new only surface reflectance- dependent descriptor which is invariant against varying illumination. Sole input is the relative direct to diffuse illumination spectrum, no assumptions about the possible reflectance spectra are made. The mapping is a purely pixel based, fast, one-pass matrix operation and can preprocess multispectral images in order to segment them into regions of homogeneous reflectance, unperturbed by varying illumination conditions (8 Refs.) DESCRIPTORS: geophysical signal processing; geophysical techniques; image colour analysis; image segmentation; remote sensing IDENTIFIERS: geophysical measurement technique; optical imaging; multispectral remote sensing; land surface; terrain mapping; image processing; image colour analysis; visible infrared; color constancy problem an; illumination invariant mapping; multispectral imagery; dichromatic illumination model; filter; diffuse illumination spectrum; surface reflectance dependent descriptor; one-pass matrix operation; image segmentation CLASS CODES: A9385 (Instrumentation and techniques for geophysical, hydrospheric and lower atmosphere research); A9365 (Data and information; acquisition, processing, storage and dissemination in geophysics); A9190 (Other topics in solid Earth physics); B7710 (Geophysical techniques and equipment); B7730 (Other remote sensing applications in Earth sciences); B6140C (Optical information, image and video signal processing); C7840 (Geography and cartography computing); C7340 (Geophysics computing); C5260B (Computer vision and image processing techniques)Record: 82
COPYRIGHT: Copyright 1995, IEE RECORD NO.: 5032564 INSPEC Abstract No: C9510-5260B-190 AUTHOR: Finlayson, G.D. CORP SOURCE: Sch. of Comput. Sci., Simon Fraser Univ., Burnaby, BC, Canada TITLE: Color constancy in diagonal chromaticity space SOURCE: Proceedings. Fifth International Conference on Computer Vision (Cat. No.95CB35744), p. xix+1117, 218-23 PLACE OF PUBL: USA ISBN: 0818670428 LANGUAGE: English PUBLISHER: IEEE Comput. Soc. Press; Los Alamitos, CA, USA SPONSOR ORG: IEEE Comput. Soc. Tech. Committee on Pattern Anal. & Machine Intelligence CONF TITLE: Proceedings of IEEE International Conference on Computer Vision CONF LOCATION: Cambridge, MA, USA; 20-23 June 1995 YEAR: 1995 COPYRIGHT NO: 0 8186 7042 8/95/$4.00 TREATMENT: T Theoretical or Mathematical RECORD TYPE: Conference Paper ABSTRACT: Simple constraints on the sets of possible surface reflectances and illuminants are exploited in a new color constancy algorithm that builds upon Forsyth's (1990) theory of color constancy. The goal defined for a color constancy algorithm is to discount variations in the color and intensity of the incident illumination and thereby extract illumination-independent descriptors of surface colors from images. Forsyth's method is based on two constraints: first, the surface colors under a canonical illuminant all fall within an established maximal convex gamut of possible colors and second that a diagonal matrix accurately maps colors between illuminants. These constraints taken together turn out to be very effective in solving for color constancy; however, other strong assumptions about the scenes are required for the method to work-the illumination must be uniform, the surfaces must be planar, and there can be no specularities. We show that these restrictions are necessary only because Forsyth sets out to recover the intensity of descriptors. At the outset we abandon 3- dimensional descriptor recovery in favor of recovering only orientation (i.e. 2 dimensions). Intensity information is factored out of the problem by mapping 3-dimensional (r, g, b) camera responses onto 2-dimensional chromaticities; specifically (r/b, g/b). We show that this "diagonal chromaticity space" has two important properties: first, gamut convexity is preserved and second illumination change is still described by a diagonal matrix. It follows that Forsyth's algorithm can be directly applied to the recover chromaticity descriptors and from these the 3D descriptor orientations can be derived. The basic algorithm is then extended to include a maximal gamut constraint on the set of illuminants that is analogous to the gamut constraint on surface colors. The diagonal chromaticity space facilitates the expression of the illumination constraint in the algorithm. Tests on real images show that the algorithm provides good color constancy (9 Refs.) DESCRIPTORS: computer vision; image colour analysis; lighting; matrix algebra; reflectivity IDENTIFIERS: diagonal chromaticity space; surface reflectances; illuminants; color constancy algorithm; illumination- independent surface color descriptors; images; canonical illuminant; maximal convex gamut; diagonal matrix; scenes; uniform illumination; planar surfaces; descriptor intensity; orientation recovery; 3D camera responses; 2D chromaticities; gamut convexity; illumination constraint; real images; possible colours CLASS CODES: C5260B (Computer vision and image processing techniques); C1250 (Pattern recognition); C4140 (Linear algebra)Record: 83
COPYRIGHT: Copyright 1995, IEE RECORD NO.: 5032563 INSPEC Abstract No: C9510-5260B-189 AUTHOR: Freeman, W.T.; Brainard, D.H. CORP SOURCE: Mitsubishi Electr. Res. Lab., Cambridge, MA, USA TITLE: Bayesian decision theory, the maximum local mass estimate, and color constancy SOURCE: Proceedings. Fifth International Conference on Computer Vision (Cat. No.95CB35744), p. xix+1117, 210-17 PLACE OF PUBL: USA ISBN: 0818670428 LANGUAGE: English PUBLISHER: IEEE Comput. Soc. Press; Los Alamitos, CA, USA SPONSOR ORG: IEEE Comput. Soc. Tech. Committee on Pattern Anal. & Machine Intelligence CONF TITLE: Proceedings of IEEE International Conference on Computer Vision CONF LOCATION: Cambridge, MA, USA; 20-23 June 1995 YEAR: 1995 COPYRIGHT NO: 0 8186 7042 8/95/$4.00 TREATMENT: T Theoretical or Mathematical RECORD TYPE: Conference Paper ABSTRACT: Vision algorithms are often developed in a Bayesian framework. Two estimators are commonly used: maximum a posteriori (MAP), and minimum mean squared error (MMSE). We argue that neither is appropriate for perception problems. The MAP estimator makes insufficient use of structure in the posterior probability. The squared error penalty of the MMSE estimator does not reflect typical penalties. We describe a new estimator, which we call maximum local mass (MLM) (10, 26, 65), which integrates the local probability density. The MLM method is sensitive to local structure of the posterior probability, which MAP is not. The new method uses an optimality criterion that is appropriate for perception tasks: it finds the most probable approximately correct answer. For the case of low observation noise, we provide an efficient approximation. We apply this new estimator to color constancy. An unknown illuminant falls on surfaces of unknown colors. We seek to estimate both the illuminant spectrum and the surface spectra from photosensor responses which depend on the product of the unknown spectra. In simulations, we show that the MLM method performs better than the MAP estimator, and better than two standard color constancy algorithms. The MLM method may prove useful in other vision problems as well (65 Refs.) DESCRIPTORS: Bayes methods; colour; computer vision; decision theory; estimation theory; noise; probability IDENTIFIERS: Bayesian decision theory; maximum local mass estimate; color constancy; vision algorithms; perception problems; local probability density; local posterior probability structure; optimality criterion; most probable approximately correct answer; low observation noise; unknown illuminant; illuminant spectrum; surface spectra; photosensor responses CLASS CODES: C5260B (Computer vision and image processing techniques); C1140E (Game theory); C1140 (Probability and statistics); C1250 (Pattern recognition)Record: 84
COPYRIGHT: Copyright 1995, IEE RECORD NO.: 5028084 INSPEC Abstract No: B9510-6140C-190; C9510-1250-105 AUTHOR: Finlayson, G.D.; Funt, B.V.; Barnard, K. CORP SOURCE: Sch. of Comput. Sci., Simon Fraser Univ., Vancouver, BC, Canada TITLE: Color constancy under varying illumination SOURCE: Proceedings. Fifth International Conference on Computer Vision (Cat. No.95CB35744), p. xix+1117, 720-5 PLACE OF PUBL: USA ISBN: 0818670428 LANGUAGE: English PUBLISHER: IEEE Comput. Soc. Press; Los Alamitos, CA, USA SPONSOR ORG: IEEE Comput. Soc. Tech. Committee on Pattern Anal. & Machine Intelligence CONF TITLE: Proceedings of IEEE International Conference on Computer Vision CONF LOCATION: Cambridge, MA, USA; 20-23 June 1995 YEAR: 1995 COPYRIGHT NO: 0 8186 7042 8/95/$4.00 TREATMENT: P Practical; T Theoretical or Mathematical RECORD TYPE: Conference Paper ABSTRACT: Illumination is rarely constant in intensity or color throughout a scene. Multiple light sources with different spectra-sun and sky, direct and interreflected light-are the norm. Nonetheless, almost all color constancy algorithms assume that the spectrum of the incident illumination remains constant across the scene. We assume the converse, that illumination does vary, in developing a new algorithm for color constancy. Rather than creating difficulties, varying illumination is in fact a very powerful constraint. Indeed tests of our algorithm using real images of an office scene show excellent results (16 Refs.) DESCRIPTORS: computer vision IDENTIFIERS: color constancy; varying illumination; multiple light sources CLASS CODES: B6140C (Optical information, image and video signal processing); C1250 (Pattern recognition); C5260B (Computer vision and image processing techniques)Record: 87
COPYRIGHT: Copyright 1995, IEE RECORD NO.: 5014209 INSPEC Abstract No: B9509-6140C-374; C9509-1250-279 AUTHOR: Sung Ho Bae; Jeong Yeop Kim; Kap Hyeon Kwon; Yeong Ho Ha CORP SOURCE: Dept. of Electr. Eng., Kyungpook Nat. Univ., Taegu, South Korea TITLE: Color image enhancement based on color constancy SOURCE: Journal of the Korean Institute of Telematics and Electronics, vol.30B, no.5, p. 103-8 ISSN: 1016-135X CODEN: CKNOEZ PLACE OF PUBL: South Korea LANGUAGE: Korean YEAR: May 1993 TREATMENT: T Theoretical or Mathematical RECORD TYPE: Journal Paper ABSTRACT: An image can be largely corrupted by the ambient illuminant, so that the image enhancement to restore natural color without respect to the ambient illuminant is needed. In this paper, a new color image enhancement technique based on color constancy is proposed. To enhance the image quality, higher values of contrast and saturation are preferred, but their excessive values make an image unnatural. Since the color constancy processing preserves only hue, while reducing the dynamic range of brightness and saturation, the technique is needed in order to compensate this phenomenon. The proposed method transforms and increases brightness and saturation simultaneously to avoid the complexity in the related transformation by analyzing the relationship between the RGB and modified IHS coordinate system (9 Refs.) DESCRIPTORS: brightness; colour; image enhancement IDENTIFIERS: color image enhancement; color constancy; natural color restoration; image quality; contrast; saturation; RGB coordinate system; modified IHS coordinate system; brightness; dynamic range reduction CLASS CODES: B6140C (Optical information, image and video signal processing); C1250 (Pattern recognition)Record: 88
COPYRIGHT: Copyright 1995, IEE RECORD NO.: 5002622 INSPEC Abstract No: A9516-8732N-001; C9509-1230D-032 AUTHOR: Courtney, S.M.; Finkel, L.H.; Buchsbaum, G. CORP SOURCE: Section on Functional Brain Imaging, Nat. Inst. of Health, Bethesda, MD, USA TITLE: A multistage neural network for color constancy and color induction SOURCE: IEEE Transactions on Neural Networks, vol.6, no.4, p. 972-85 ISSN: 1045-9227 CODEN: ITNNEP PLACE OF PUBL: USA LANGUAGE: English YEAR: July 1995 COPYRIGHT NO: 1045-9227/95/$04.00 TREATMENT: T Theoretical or Mathematical; X Experimental RECORD TYPE: Journal Paper ABSTRACT: A biologically-based multistage neural network is presented which produces color constant responses to a variety of color stimuli. The network takes advantage of several mechanisms in the human visual system, including retinal adaptation, spectral opponency, and spectrally-specific long- range inhibition. This last stage is a novel mechanism based on cells which have been described in cortical area V4. All stages include nonlinear response functions. The model emulates human performance in several psychophysical paradigms designed to test color constancy and color induction. We measured the amount of constancy achieved with both natural and artificial simulated illuminants, using homogeneous grey backgrounds and more complex backgrounds, such as Mondrians. On average, the model performs as well or better than the average human color constancy performance under similar conditions. The network simulation also displays color induction and assimilation behavior consistent with human perceptual data (60 Refs.) DESCRIPTORS: colour vision; image colour analysis; neural nets; physiological models; visual perception IDENTIFIERS: multistage neural network; color constancy; color induction; human visual system; retinal adaptation; spectral opponency; long-range inhibition; visual perception CLASS CODES: A8732N (Colour vision: detection, adaptation and discrimination); A8732S (Psychophysics of vision, visual perception, binocular vision); C1230D (Neural nets); C1250 (Pattern recognition); C1290L (Systems theory applications in biology and medicine)Record: 89
COPYRIGHT: Copyright 1995, IEE RECORD NO.: 4988891 INSPEC Abstract No: B9508-6140C-406; C9508-1250-316 AUTHOR: Funt, B.V.; Finlayson, G.D. CORP SOURCE: Sch. of Comput. Sci., Simon Fraser Univ., Burnaby, BC, Canada TITLE: Color constant color indexing SOURCE: IEEE Transactions on Pattern Analysis and Machine Intelligence, vol.17, no.5, p. 522-9 ISSN: 0162-8828 CODEN: ITPIDJ PLACE OF PUBL: USA LANGUAGE: English YEAR: May 1995 COPYRIGHT NO: 0162-8828/95/$04.00 TREATMENT: T Theoretical or Mathematical; X Experimental RECORD TYPE: Journal Paper ABSTRACT: Objects can be recognized on the basis of their color alone by color indexing, a technique developed by Swain-Ballard (1991) which involves matching color-space histograms. Color indexing fails, however, when the incident illumination varies either spatially or spectrally. Although this limitation might be overcome by preprocessing with a color constancy algorithm, we instead propose histogramming color ratios. Since the ratios of color RGB triples from neighboring locations are relatively insensitive to changes in the incident illumination, this circumvents the need for color constancy preprocessing. Results of tests with the new color-constant-color-indexing algorithm on synthetic and real images show that it works very well even when the illumination varies spatially in its intensity and color (7 Refs.) DESCRIPTORS: image colour analysis; lighting; object recognition IDENTIFIERS: object recognition; color indexing; illumination; color constancy; color ratio histograms CLASS CODES: B6140C (Optical information, image and video signal processing); C1250 (Pattern recognition)
|
||||||||||||||||||||||||||||||||||||||
|
||||||||||||||||||||||||||||||||||||||
 | ||||||||||||||||||||||||||||||||||||||
| FirstSearch. Copyright 1992-1999 OCLC as to electronic presentation and platform. All rights reserved. | ||||||||||||||||||||||||||||||||||||||