Showing papers on "Alpha compositing published in 1995"

Flexible dram access in a frame buffer memory and system

Abstract: A frame buffer dynamic random access memory (FBRAM) is disclosed that enables accelerated rendering of Z-buffered graphics primitives. The FBRAM converts read-modify-write transactions such as Z-buffer compare and RBG alpha blending into a write only operation. The FBRAM also implements two levels of internal pixel caches, and a four-way interleaved frame buffer.

Multi-image compositing

Abstract: Image compositing apparatus and methodology for the creation, in a defined volume of three-dimensional space, of a composite organization of plural images/visual phenomena, including at least one projected real image (104), displayed in formats including (a) front-to-rear, (b) side-by-side and (c) overlapping and intersecting, adjacency The apparatus incorporates different unique arrangements of visual sources (110, 112), and optical elements including concave reflectors (114), beam splitters (116) and image-forming/image-transmissive scrim/screen structures (334) In one important modification of the system, which does not necessarily require compositing, a projected real image is derived from an image-producing data stream containing three-dimensional image cues selected from the group consisting of shading, occlusion, perspective, motion parallax, size vs depth, light (chroma value) vs depth and definition vs depth In a further important modification of the invention, a system (620) is proposed which allows a viewer/user to interact directly with a projected real image, in a manner allowing the manipulation of one or more characteristics or aspects of the image

Memory and graphics controller which performs pointer-based display list video refresh operations

Abstract: A graphics controller (IMC) which performs pointer-based and/or display list-based video refresh operations that enable screen refresh data to be assembled on a per window basis, thereby greatly increasing the performance of the graphical display. The graphics controller maintains pointers to various buffers in system memory comprising video or graphics display information. The graphics controller manipulates respective object information workspace memory areas corresponding to each object or window, wherein the workspace areas specify data types, color depths, 3D depth values, alpha blending information, screen position, etc. for the respective window or object on the screen. Each workspace area also includes static and dynamic pointers which point to the location in system memory where the pixel data for the respective window or object is stored. The graphics controller utilizes this information, as well as information received from the software driver regarding screen changes, to assemble a display refresh list in system memory. This information is used during the screen refresh to display the various windows or objects on the screen very quickly and efficiently. Thus, the video display can be updated with new video data without requiring any system bus data transfers, which are required in prior art computer system architectures. The graphics controller dynamically adjusts the display refresh list for movement of objects and changes in relative depth priority which appear on the display. Thus the video data for the various windows and objects is stored in respective memory areas in the system memory, and pointers assembled in the display refresh list are used to reference this data during screen updates. Therefore, data is not required to be moved in or out of a frame buffer to reflect screen changes. Rather, in many instances, either the video data for a respective window or object is changed, or only the pointers in the display refresh list are manipulated, to affect a screen change.

Method for alpha blending images utilizing a visual instruction set

Abstract: An image alpha blending method utilizing a parallel processor is provided. The computer-implemented method includes the steps of loading unaligned multiple word components into a processor in one machine instruction, each word component associated with a pixel of an image; alpha blending the multiple word components of different source images and a control image in parallel; and storing the alpha blended multiple word components of a destination image into memory in parallel.

Alpha blending arithmetic unit

Abstract: PURPOSE:To perform an alpha blending operation at a high speed by means of a simple logic circuit and also to improve the speed of drawing an object. CONSTITUTION:The multiplication/division devices 12 and 13 consist of the devices that shift the bits and control the output in order to perform both multiplication and division at a time, the device 12 performs the multiplication of both input data of the current color data and the value obtained by subtracting the alpha value from 255 and the division of 255 at a time. The device 13 performs simultaneously the multiplication of both input data of the source color data and the alpha value and the division of 255. By adding together these outputs, an alpha blending operation is carried out.

Structured video and the construction of space

Abstract: Image sequences can now be synthesized by compositing elements - objects, backgrounds, people -frompre-existing sourceimages. What are the rules that govern the placement of these elements in their new frames? If geometric projection is assumed togovern the composition, there is some freedom to move the elements about, but the range of placements is quite limited. Further-more, projective geometry is not perceptually ideal —think of the distortions seen at the edges of wide angle photographs. Thesedistortions are not found in perspective paintings: painters modify the portrayal of certain objects to make them perceptually cor-rect. This paper first reviews projective geometry in the context of image compositing and then introduces perceptually based com-position. Its basis in human vision is analyzed and its application to image compositing discussed.Keywords: structured video, image compostion, visual perception, perspective.1. Structured Video and SpaceIn traditional video the frame is indivisible and the sequence —

Frame buffer random access memory and system.

Abstract: A frame buffer dynamic random access memory (FBRAM) (71) is disclosed that enables accelerated rendering of Z-buffered graphics primitives. The FBRAM converts read-modify-write transactions such as Z-buffer compare and RBG alpha blending into a write only operation. The FBRAM also implements two levels of internal pixel caches (56), a pixel ALU (58), and a four-way interleaved frame buffer.