K. Chiu, M. Herf, P. Shirley, S. Swamy, C. Wang, and K. Zimmerman. Spatially Nonuniform Scaling Functions for High Contrast Images. In Proceedings of Graphics Interface '93, pages 245--253, San Francisco, CA, May 1993. Morgan Kaufmann.  Home/Search   Document Details and Download   Summary   Related Articles   Check

.... Time dependent Tumblin Rushmeier 1993 [41] Upstill 1985 [43] Miller et al. 1984 [22] Cohen et al. 2001 [6] Tumblin et al. 1999 [40] Scheel et al. 2000 [33] Ward Larson et al. 1997 [18] Ward 1994 [45] Oppenheim et al. 1968 [26] Stockham 1993 [38] Chiu et al. 1993 [5] Schlick 1994 [34] Jobson et al. 1997 [15] Pattanaik et al. 1998 [27] Tumblin Turk 1999 [42] Ashikhmin 2002 [2] Fattal et al. 2002 [9] Reinhard et al. 2002 [31] Durand Dorsey 2002 [8] Ferwerda et al. 1996 [10] Durand Dorsey 2000[7] Pattanaik et al. 2000 [28] Figure 3: ....

....are preserved. Further work by Stockham [38] in 1972 tied the concept of homorphic filtering to properties of early portions of the HVS. He developed a visual model based on these properties and used it to define a measure of image quality. Chiu, Herf, Shirley, Swamy, Wang and Zimmerman s [5] investigation into global operators led them to believe that the solution should be local instead, as applying the same mapping to each pixel could produce incorrect results. With an HDR image there is no perfect compression curve that fits every pixel in an image, so a method of incorporating ....

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K. Chiu, M. Herf, P. Shirley, S. Swamy, C. Wang, and K. Zimmerman. Spatially nonuniform scaling functions for high contrast images. In Graphics Interface '93, pages 245--253, Toronto, Ontario, Canada, May 1993. Canadian Information Processing Society.

....these coarsest levels fails badly for linear filter methods because some parts of the scene s step like large feature have escaped compression by mixing with fine details of the paper texture. The resulting display image, as shown in Figure 3, suffers from artifacts known variously as halos [1], overshoot undershoot or gradient reversals [19] We have devised a new hierarchy that more closely follows artistic methods for scene renderings. Each level of the hierarchy is made from a simplified version of original scene made of sharp boundaries and smooth shadings. We named the ....

....troublesome because compressive functions destroy important details in highlights and shadows unless adjusted according to local image features. Photographers use dodging and burning (moving hand held masks) to locally adjust print exposure in a darkroom, inspiring an early paper by Chiu et al. [1] that constructs a locally varying attenuation factor m by repeatedly clipping and low pass filtering the scene. Though their method works well in smoothly shaded regions, any small, bright scene feature causes strong attenuation of neighboring pixels and surrounds the feature with a noticeable ....

K. Chiu, M.Herf, P. Shirley, S. Swamy, C. Wang, and K. Zimmerman. Spatially nonuniform scaling functions for high contrast images. In Proceedings of Graphics Interface 93, pages 245--254, May 1993.

....of light is infinite, which implies that any simulation is in a steady state. This is usually appropriate since the time it takes light to travel in common scenes is not perceivable. The following sections touch briefly on several important concepts, which are handled in much detail by Glassner [3]. 1 Solid Angles Key concepts in the radiometric definitions are the ideas of solid angle and projection. When we think of a solid angle we usually think of some object projected onto a unit sphere. This projection is the solid angle of the object as view from the center of the sphere (Figure 1) ....

....the BRDF is integrated over the hemisphere of reflected directions we will get the total reflectance for an incoming direction 0 . This value must be less than or equal to one: R#x; 0 #= Z# f r #x; 0 ; # cos #d 0 # 1:0 : 9) Several models for BRDF are described in Glassner [3] including the most commonly used models of Lambert and Phong, as well as more complicated models employing Fresnel equations and the empirical models of Ward [11] An additional model which is not covered by Glassner but deserves mention is the modified Phong model of Lafortune and Willems [7] ....

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K. Chiu et al. "Spatially Nonuniform Scaling Functions for High Contrast Images," Proceedings of Graphics Interface, 1993.

.... algorithms (radiosity, Monte Carlo ray tracing) usually generate pictures with much higher dynamic ranges than direct illumination ones: a factor of 2000 between the highest and the lowest intensity values is common and a factor of 30000 is sometimes reached with special illumination cases (Chiu et al. 1993). Therefore traditional 24 bit picture representations with a dynamic range of 256 are inadequate. Moreover, when applying gamma correction, even pure 24 bit pictures can create color bandings for low values (Hall 1989) showing that a greater dynamic range is needed. Ward has proposed a technique ....

K. Chiu, M. Herf, P. Shirley, S. Swamy, C. Wang, and K. Zimmerman. Spatially nonuniform scaling functions for high contrast images. In Proceedings of Graphics Interface 93, pages 182--191, 1993.

....devices. While the human eye has an input range in the order of 10 5 to 10 5 cd m 2 (cf. 16] typical displays can only show values between 1 and 100 cd m 2 , so a transformation is obviously necessary. In order to deal with these problems, tone operators have been investigated in e.g. [16, 1, 18]. These operators take as input a real world radiance and returns a corresponding display value. Thus, instead of displaying L , the displayed value should be : L = T ( L) 4) where T ( is the tone operator. In order to incorporate this in adaptive sampling, we propose that the ....

K. Chiu, M. Herf, P. Shirley, S. Swamy, C. Wang, and K. Zimmerman. Spatially non-uniform scaling functions for high contrast images. In Proceedings of Graphics Interface 1993, pages 245--253, Toronto, May 19--21 1993.

....they still did not capture local variations in intensity well. The metrics employ the Fourier transform which does not preserve local spatial characteristics. Finally, the metrics were designed and used more for purposes of visual similitude rather than as guiding tools in a refinement process. In [1] methodologies have been proposed to include perceptual considerations into the rendering process. Although laudable, these methodologies are cumbersome to incorporate and are restricted to specific rendering algorithms. Much effort has been expended in incorporating the characteristics of the HVS ....

Chiu K., Herf M., Shirley P., Swamy S., Zimmerman K., "Spatially Nonuniform Scaling Functions for High Contrast Images", Proceedings of Graphics Interface'93, May 1993, pp. 245-254.

.... gamut, limited dynamic range) in order to display a picture that evokes the same visual sensation as the equivalent real scene [8] Several comprehensive solutions, using work done in color science [13] have been proposed for color gamut limitations [9, 6, 10] But, except two very recent papers [3, 12], dynamic range limitations have usually been ignored or solved only for specific cases. This paper proposes some fast and simple quantization techniques to display high dynamic range pictures on low dynamic range devices. For simplicity, the algorithms are first explained on greyscale pictures ....

....(Val) 0:5c because it provides N equal quantization steps. Finding a good TRF is a complex task which involves many different fields such as anatomy of the human eye, technology of the visualization device, color science, principles of subjective perception [8] As said, until very recent papers [12, 3], most work on TRF functions in computer graphics has been done on color reproduction, usually ignoring brightness reproduction. The most widely used TRF in computer graphics is gamma corrected linear mapping : F q (Val) Val HiVal 1=q where q 2 [1; 3] 2) 1 This picture was provided by ....

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K.Chiu, M.Herf, P.Shirley, S.Swamy, C.Wang, K.Zimmerman, Spatially Non Uniform Scaling Functions for High Contrast Images, Proceedings of Graphics Interface 93, p182-191, 1993

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K. Chiu, M. Herf, P. Shirley, S. Swamy, C. Wang, and c The Eurographics Association 2002. K. Zimmerman. Spatially nonuniform scaling functions for high contrast images. In Graphics Interface '93, pages 245--253, Toronto, Ontario, Canada, May 1993. Canadian Information Processing Society. 10, 12, 15

....quasi random samples and related them to equidistribution and its measure [1, 28, 71, 83, 50, 4] the application of these mathematical results in computer graphics is still limited. In this chapter, we also generalize the idea of equidistribution and propose a new multi jittered sampling method [7], whose samples are equidistributed in any sub domain. In a two dimensional square domain, the multi jittered sampling method superimposes the jittered cells and N rooks cells, and generate the samples that are jittered as well as N rooks in order to have equidistribution in two dimensions and in ....

....full solution might be an overkill. One reason is that a fast but coarse approximation can produce an image without a significant degradation of quality [58] The other reasons relate to the non linear transformation of a real world image to a screen image which only allows a small intensity range [73, 7]. The non linear transformation of Tumblin and Rushmeier suggests that the full intensity range of the screen image should be a nonlinear function to the actual intensity range of the real world image, i.e. a real world image is mapped only to a portion of the intensity range on the screen. The ....

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K. Chiu, M. Herf, P. Shirley, S. Swamy, C. Wang, and K. Zimmerman. Spatially nonuniform scaling functions for high contrast images. Graphics Interface, 1993.

....viewers. 3.2 Digital Glare Filter Generation The glare formulae of Section 3.1 can be applied directly to digital images by using a digital point spread function to spread energy in high intensity pixels to nearby pixels. This basic strategy has been used by Nakamae et al. 20] and Chiu et al. [7]. Unlike these previous approaches, we use di#erent flare filters based on the adaptation state of the viewer. To develop a filter for a particular image, we first construct digital versions of f0###, f1###, f2###,andf3###.Sinceeach of these filters must have unit volume, we can calculate each ....

....a few holes in the leaves of the tree. Note that, as expected when viewing a bright scene, the lenticular halo is missing from Figure 16. All of these images have some burn out, where the value of the pixel goes above one. Ultimately, a more sophisticated tone mapping algorithm should be used [32, 7, 34, 27], so that the images will have the appropriate degree of object visibility, and qualitative lightness or darkness. This issue is not addressed in this work. 6 Conclusion We have presented the mechanisms of glare in the human visual system, and have provided quantitative formulae used by the ....

Chiu, K., Herf, M., Shirley, P., Swamy, S., Wang, C., and Zimmerman, K. Spatially nonuniform scaling functions for high contrast images. In Graphics Interface '93 (May 1993), pp. 245-- 244.

....threshold a few percent of Lw . Such a threshold will ensure that any luminaire that can change 9 Lw should be chosen according to a perceptual viewer model, such as the model implemented by Tumblin and Rushmeier [42] Lw may also vary from pixel to pixel if spatially varying mappings are used [4]. Such models will become increasingly important as physically based rendering becomes more popular. b obstacle a c d e (region of importance for luminaire a covers all cells. a,c a,c,e a,e a a,c,e a,b a,b,d a,d,e Figure 11: A subdivision of space where luminaire is a member of L bright for a ....

K. Chiu, M. Herf, P. Shirley, S. Swamy, C. Wang, and K. Zimmerman. Spatially nonuniform scaling functions for high contrast images. In Graphics Interface '93, pages 245--244, May 1993.

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K. Chiu, M. Herf, P. Shirley, S. Swamy, C. Wang, and K. Zimmerman. Spatially nonuniform scaling functions for high contrast images. In Graphics Interface '93, pages 245--244, May 1993.

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K. Chiu, M. Herf, P. Shirley, S. Swamy, C. Wang, and K. Zimmerman. Spatially Nonuniform Scaling Functions for High Contrast Images. In Proceedings of Graphics Interface '93, pages 245--253, San Francisco, CA, May 1993. Morgan Kaufmann.

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K. Chiu, M. Herf, P. Shirley, S. Swamy, C. Wang, and K. Zimmerman. Spatially Nonuniform Scaling Functions for High Contrast Images. In Proceedings of Graphics Interface '93, pages 245--253, San Francisco, CA, 1993. Morgan Kaufmann.

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CHIU, K., HERF, M., SHIRLEY, P., SWAMY, S., WANG, C., AND ZIMMERMAN, K. 1993. Spatially nonuniform scaling functions for high contrast images. In Proc. Graphics Interface '93, 245-- 253.

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K. Chiu, M. Herf, P. Shirley, S. Swamy, C. Wang and K. Zimmerman "Spatially nonuniform scaling functions for high contrast images," Proceedings of Graphics Interface '93, Toronto, Canada, (May 1993).

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Chiu K., Herf M., Shirley P., Swamy S., Wang C. and Zimmerman K., Spatially Non Uniform Scaling Functions for High Contrast Images, Proceedings of Graphics Interface '93, 1993, 182-191.

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K. Chiu, M. Herf, P. Shirley, S. Swamy, C. Wang, and K. Zimmerman. Spatially nonuniform scaling functions for high contrast images. In Proceedings of Graphics Interface '93, pages 245--253, 1993.

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Chiu, K., Herf, M., Shirley, P., Swamy, S., Wang, C., Zimmerman, K. "Spatially Nonuniform Scaling Functions for High Contrast Images", Proceedings of Graphics Interface 93, pp.182-191, 1993.

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K. Chui, M. Herf, P. Shirley, S. Swamy, C. Wang, and K. Zimmerman. Spatially nonuniform scaling functions for high contrast images. In Proceedings of Graphics Interface, pages 245--254, May 1993.

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CHS + 93. Chiu, Herf, Shirley, Swamy, Wang, and Zimmerman. Spatially nonuniform scaling functions for high contrast images. In Proc. Graphics Interface, 1993.

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K. Chiu, M. Herf, P. Shirley, S. Swamy, C. Wang, and K. Zimmerman. Spatially Nonuniform Scaling Functions for High Contrast Images. In Proceedings of Graphics Interface '93, pages 245-253, May 1993.

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Chiu K., Herf M., Shirley P., Swamy S., Wang C. and Zimmerman K., Spatially Non Uniform Scaling Functions for High Contrast Images, Proceedings of Graphics Interface '93, 1993, 182-191.

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Chui, K., M. Herf, P. Shirley, C. Wang, and K. Zimmerman. 1993. "Spatially Nonuniform Scaling Functions for High Contrast Images," Graphics Interface `93, pp. 245-253.

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