Alpha compositing

About: Alpha compositing is a research topic. Over the lifetime, 482 publications have been published within this topic receiving 11035 citations. The topic is also known as: alpha blend & alpha channel.

Cross Dissolve Without Cross Fade: Preserving Contrast, Color and Salience in Image Compositing

Abstract: Linear interpolation is the standard image blending method used in image compositing. By averaging in the dynamic range, it reduces contrast and visibly degrades the quality of composite imagery. We demonstrate how to correct linear interpolation to resolve this longstanding problem. To provide visually meaningful, high level control over the compositing process, we introduce three novel image blending operators that are designed to preserve key visual characteristics of their inputs. Our contrast preserving method applies a linear color mapping to recover the contrast lost due to linear interpolation. Our salience preserving method retains the most informative regions of the input images by balancing their relative opacity with their relative saliency. Our color preserving method extends homomorphic image processing by establishing an isomorphism between the image colors and the real numbers, allowing any mathematical operation defined on real numbers to be applied to colors without losing its algebraic properties or mapping colors out of gamut. These approaches to image blending have artistic uses in image editing and video production as well as technical applications such as image morphing and mipmapping. Categories and Subject Descriptors (according to ACM CCS): I.3.3 [Computer Graphics]: Picture/Image Generation

Jim Blinn's corner: dirty pixels

Abstract: 1. The World's Largest Easter Egg and What Came Out of It 2. What We Need Around Here Is More Aliasing 3. Return of the Jaggy 4. How Many Different Curves Are There? 5. Dirty Pixels 6. Cubic Curve Update 7. Triage Tables 8. The Wonderful World of Video 9. Uppers and Downers 10. Uppers and Downers, Part II 11. The World of Digital Video 12. How I Spent My Summer Vacation-1976 13. NTSC: Nice Technology, Super Color 14. What's the Deal with the DCT? 15. Quantization Error and Dithering 16. Compositing-Theory 17. "Composting"-Practice 18. How to Attend a SIGGRAPH Conference 19. Three Wrongs Make a Right 20. Fun with Premultiplied Alpha

Compositing two-dimensional and three-dimensional image layers

Abstract: Methods and apparatus, including computer program products, implementing and using techniques for generating a composite image from both two-dimensional (2D) image layers and three-dimensional (3D) image layers. In one embodiment, the image layers are arranged in a sequence in which a top 3D image layer is separated from a bottom 3D image layer by a 2D image layer and the image layers are rendered according to the sequence. In another embodiment, at least one of the image layers is associated with an adjustment layer, and rendering the composite image includes determining whether each current image layer has an associated adjustment layer with a dimensionality different from that of the current image layer, and if it does, applying the adjustment layer accordingly. In another embodiment, at least one of the image layers is associated with a track matte.

PhotoSketch: a sketch based image query and compositing system

Abstract: We introduce a system for progressively creating images through a simple sketching and compositing interface. A large database of over 1.5 million images is searched for matches to a user's binary outline sketch; the results of this search can be combined interactively to synthesize the desired image. We introduce image descriptors for the task of estimating the difference between images and binary outline sketches. The compositing part is based on graph cut and Poisson blending. We demonstrate that the resulting system allows generating complex images in an intuitive way.

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.