Article Blue screen matting Share on Authors: Alvy Ray Smith Microsoft Corporation, One Microsoft Way, Redmond, WA Microsoft Corporation, One Microsoft Way, Redmond, WAView Profile , James F. Blinn Microsoft Corporation, One Microsoft Way, Redmond, WA Microsoft Corporation, One Microsoft Way, Redmond, WAView Profile Authors Info & Claims SIGGRAPH '96: Proceedings of the 23rd annual conference on Computer graphics and interactive techniquesAugust 1996 Pages 259–268https://doi.org/10.1145/237170.237263Published:01 August 1996 249citation2,665DownloadsMetricsTotal Citations249Total Downloads2,665Last 12 Months77Last 6 weeks2 Get Citation AlertsNew Citation Alert added!This alert has been successfully added and will be sent to:You will be notified whenever a record that you have chosen has been cited.To manage your alert preferences, click on the button below.Manage my AlertsNew Citation Alert!Please log in to your account Save to BinderSave to BinderCreate a New BinderNameCancelCreateExport CitationPublisher SiteGet Access

No abstract available.

No abstract available.

The 2-pass tranformation replaces a 2-D (2-dimensional) transformation with a sequence of orthogonal, simpler 1-D transformation. It may be used for the closely related processes of texture mapping and warping in computer graphics and image processing. First, texture maps onto planar quadric and superquadric surfaces and, second, planar bicubic and biquadratic warps of images are shown to be 2-pass transformable. A distinction between serial and parallel warps is introduced to solve a confusion in terms between computer graphics and image processing. It is shown that an n-th order serial polynomial warp is equivalent to an (n2+n)-th order parallel polynomial warp. It is also shown that the serial equivalent to a parallel polynomial warp is generally not a polynomial warp, being more complicated than a polynomial. The unusual problem of bottlenecking and the usual one of antialiasing are discussed in the 2-pass context.

Although fractal models of natural phenomena have received much attention recently, there are other models of complex natural objects which have been around longer in Computer Imagery but are not widely known. These are procedural models of plants and trees. An interesting class of these models is presented here which handles plant growth, sports an efficient data representation, and has a high “database amplification” factor. It is based on an extension of the well-known formal languages of symbol strings to the lesser-known formal languages of labeled graphs. It is so tempting to describe these plant models as “fractal” that the similarities of this class of models with fractal models are explored in an attempt at rapprochement. The models are not fractal so the common parts of fractal theory and plant theory are abstracted to form a class of objects, the graftals. This class may prove to be of great interest to the future of Computer Imagery. Determinism is shown to provide adequate complexity, whereas randomness is only convenient and often inefficient. Finally, a nonfractal, nongraftal family of trees by Bill Reeves is introduced to emphasize some of the paper's nongrammatical themes.

Currerntly texture mapping onto projections of 3-D surfaces is time consuming and subject to considerable aliasing errors. Usually the procedure is to perform some inverse mapping from the area of the pixel onto the surface texture. It is difficult to do this correctly. There is an alternate approach where the texture surface is transformed as a 2-D image until it conforms to a projection of a polygon placed arbitrarily in 3-space. The great advantage of this approach is that the 2-D transformation can be decomposed into two simple transforms, one in horizontal and the other in vertical scanline order. horizontal scanline order, Sophisticated light calculation is also time consuming and difficult to calculate correctly on projected polygons. Instead of calculating the lighting based on the position of the polygon, lights, and eye, the lights and eye can be transformed to a corresponding position for a unit square which we can consider to be a canonical polygon. After this canonical polygon is correctly textured and shaded it can be easily conformed to the projection of the 3-D surface.

To fill a connected area of a digital image is to change the color of all and only those pixels in the area. Fill algorithms for areas defined by sharp boundaries (e.g., a white area surrounded by a black curve) have been implemented at several color computer graphics installations. This paper presents an algorithm for the more difficult problem of filling areas with shaded boundaries (e.g., a white area surrounded by a curve consisting of several shades of gray). These images may arise from digitizing photographs or line drawings with a scanning video camera, or they may be generated by programs which produce antialiased line segments or dekink black-and-white images. When an area in such an image is to be filled with a new color, it is desirable to have the fill algorithm understand the shaded edges and maintain the shading with shades of the new color instead of the old. The tint fill algorithm presented here accomplishes this task. Its name arises from its ability to change only the tint (hue and saturation) of a pixel, leaving the value (blackness) unchanged. Although the algorithm was motivated by and is written in terms of color, it has a more general interpretation, which is also presented.

Digital control of color television monitors—in particular, via frame buffers—has added precise control of a large subset of human colorspace to the capabilities of computer graphics. This subset is the gamut of colors spanned by the red, green, and blue (RGB) electron guns exciting their respective phosphors. It is called the RGB monitor gamut. Full-blown color theory is a quite complex subject involving physics, psychology, and physiology, but restriction to the RGB monitor gamut simplifies matters substantially. It is linear, for example, and admits to familiar spatial representations. This paper presents a set of alternative models of the RGB monitor gamut based on the perceptual variables hue (H), saturation (S), and value (V) or brightness (L). Algorithms for transforming between these models are derived. Particular emphasis is placed on an RGB to HSV non-trigonometric pair of transforms which have been used successfully for about four years in frame buffer painting programs. These are fast, accurate, and adequate in many applications. Computationally more difficult transform pairs are sometimes necessary, however. Guidelines for choosing among the models are provided. Psychophysical corrections are described within the context of the definitions established by the NTSC (National Television Standards Committee).

The specialization of the theory of cellular spaces (cellular automata) to those spaces which compute partial recursive functions is presented.Neighborhood reduction and state-set reduction are shown to be particularly simple in this special theory, and one dimension is proved to be sufficient for computation universality.Several computation-universal cellular spaces (CUCS's) are exhibited which are simple in the sense that each cell has only a small number q of states and a small number p of neighbors.For example, a 1-dimensional CUCS with pq = 36 is presented.Two quite different proofs of the existence of a I-dimensional CUCS with only two neighbors are given.Finally, one of the theorems derived is used to settle three open decidability questions.

An r-ary shift-register sequence is desired that has arbitrary cycle length L≤rkfor arbitrary r and k, where k is the number of stages (degree) of the shift register. The existence of such sequences is established for "almost all" cycle lengths L. Furthermore, existence of such sequences which are "zero free" for almost all cycle lengths L is proved.