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.

Multi-scale image harmonization

Abstract: Traditional image compositing techniques, such as alpha matting and gradient domain compositing, are used to create composites that have plausible boundaries. But when applied to images taken from different sources or shot under different conditions, these techniques can produce unrealistic results. In this work, we present a framework that explicitly matches the visual appearance of images through a process we call image harmonization, before blending them. At the heart of this framework is a multi-scale technique that allows us to transfer the appearance of one image to another. We show that by carefully manipulating the scales of a pyramid decomposition of an image, we can match contrast, texture, noise, and blur, while avoiding image artifacts. The output composite can then be reconstructed from the modified pyramid coefficients while enforcing both alpha-based and seamless boundary constraints. We show how the proposed framework can be used to produce realistic composites with minimal user interaction in a number of different scenarios.

Blurred image region detection and classification

Abstract: Many digital images contain blurred regions which are caused by motion or defocus. Automatic detection and classification of blurred image regions are very important for different multimedia analyzing tasks. This paper presents a simple and effective automatic image blurred region detection and classification technique. In the proposed technique, blurred image regions are first detected by examining singular value information for each image pixels. The blur types (i.e. motion blur or defocus blur) are then determined based on certain alpha channel constraint that requires neither image deblurring nor blur kernel estimation. Extensive experiments have been conducted over a dataset that consists of 200 blurred image regions and 200 image regions with no blur that are extracted from 100 digital images. Experimental results show that the proposed technique detects and classifies the two types of image blurs accurately. The proposed technique can be used in many different multimedia analysis applications such as image segmentation, depth estimation and information retrieval.

High-performance polygon rendering

Abstract: This paper describes a system architecture for realtime display of shaded polygons. Performance of 100,000 lighted, 4-sided polygons per second is achieved. Vectors and points draw at the rate of 400,000 per second. High-speed pan and zoom, alpha blending, realtime video input, and antialiased lines are supported. The architecture heavily leverages parallelism in several forms: pipeline, vector, and array processing. It is unique in providing efficient and balanced graphics that support interactive design and manipulation of solid models. After an overview of algorithms and computational requirements, we describe the details of the implementation. Finally, the unique features enabled by the architecture are highlighted.

PNG (Portable Network Graphics) Specification Version 1.0

Abstract: This document describes PNG (Portable Network Graphics), an extensible file format for the lossless, portable, well-compressed storage of raster images. PNG provides a patent-free replacement for GIF and can also replace many common uses of TIFF. Indexed-color, grayscale, and truecolor images are supported, plus an optional alpha channel. Sample depths range from 1 to 16 bits.

Chap - a SIMD graphics processor

Abstract: Special purpose processing systems designed for specific applications can provide extremely high performance at moderate cost. One such processor is presented for executing graphics and image processing algorithms as the basis of a digital film printer. Pixels in the system contain four parallel components: RGB for full color and an alpha channel for retaining transparency information. The data path of the processor contains four arithmetic elements connected through a crossbar network to a tessellated scratchpad memory. The single instruction, multiple data stream (SIMD) processor executes instructions on four pixel components in parallel. The instruction control unit (ICU) maintains an activity stack for tracking block-structured code, using data-dependent activity flags for conditional disabling subsets of the ALUs. Nested loops and if-then-else constructs can be programmed directly, with the ICU disabling and reenabling ALUs on the basis of their individual status bits.