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.

3-Level DWT Image Watermarking Against Frequency and Geometrical Attacks

Abstract: This paper introduces a robust image watermarking technique for the copyright protection. The proposed method is based on 3-level discrete wavelet transform (DWT). Encoded secret image using spiral scanning is hidden by alpha blending technique in LL sub bands. During embedding process, secret image is dispersed within LL band depending upon alpha value. Encoded secret images are extracted and decoded to recover the original secret image. The experimental results demonstrate that the watermarks generated with the proposed algorithm are invisible and the quality of watermarked image and the recovered image are improved. The scheme is found robust to various image processing attacks such as JPEG compression, Gaussian noise, blurring, median filtering and rotation. Index Terms—Image watermarking, 3-level DWT, wavelet transform, attacks, mean square error (MSE), peak signal to noise ratio (PSNR).

A Novel Double-Image Encryption Algorithm Based on Rossler Hyperchaotic System and Compressive Sensing

Abstract: In this paper, a novel double-image compression-encryption algorithm is proposed by combining Rossler hyperchaos and compressive sensing. In the proposed scheme, the sparse matrixes obtained by performing two-dimensional discrete wavelet transform on two plain images are first scrambled and compressed by index confusion and compressive sensing. Next, the compressed matrixes are linearly quantized, and then variable step length Josephus confusion and bitwise exclusive-OR operation are performed on them. The final noise-like cipher image is generated by hiding half of the encrypted image into the alpha channel of the other half of encrypted image. In order to realize “One cipher image corresponds to one key”, a novel key generation mechanism is designed. Finally, the simulation analyses indicate that the proposed double-image encryption scheme has high transmission efficiency. Meanwhile, the average local information entropy of the cipher image is about 0.902 and the decryption quality is as high as 30 dB.

Accelerating and benchmarking radix-k image compositing at large scale

Abstract: Radix-k was introduced in 2009 as a configurable image compositing algorithm. The ability to tune it by selecting k-values allows it to benefit more from pixel reduction and compression optimizations than its predecessors. This paper describes such optimizations in Radix-k, analyzes their effects, and demonstrates improved performance and scalability. In addition to bounding and run-length encoding pixels, k-value selection and load balance are regulated at run-time. Performance is systematically analyzed for an array of process counts, image sizes, and HPC and graphics clusters. Analyses are performed using compositing of synthetic images and also in the context of a complete volume renderer and scientific data. We demonstrate increased performance over binary swap and show that 64 megapixels can be composited at rates of 0.08 seconds, or 12.5 frames per second, at 32 K processes.

System and method for monochromatic tinting using saturation maps

Abstract: There are provided systems and methods for tinting an image by monochromatic tinting using saturation maps for use by an application providing a user interface supporting customizable tinted images. By using saturation map and a monochromatic value map derived from the image and configuring the saturation map to specify areas for tinting, a tint color can be applied to the image by a series of quickly processed arithmetic calculations. This provides a lightweight and high quality method for tinting images within an application without wasting unnecessary network bandwidth or processor resources. Furthermore, the method can be adapted to apply multiple tint colors for multiple tints or use an alpha channel to restore color information lost due to the monochromatic value map. The resulting tinted image can also be used as a texture for a three-dimensional rendering engine.

Architecture of a coprocessor module for image compositing

Abstract: This paper proposes the architecture of a coprocesssor module for image compositing. The emerging MPEG-4 standard for multimedia applications allows script-based compositing of audiovisual scenes from multiple audio and visual objects. This involves the composition of the output frame by alpha-blending of Video Object Planes (VOPs). A coprocessor architecture is presented, that works in parallel to an MPEG-4 video- and audio-decoder, and performs computation and bandwidth intensive low-level algorithms for image compositing. The processor has on-chip memories that allow preload of data before it is accessed. VHDL implementation and synthesis for a 0.5/spl mu/ process show an estimate of 100 MHz achievable clock-frequency and 10 k gates for arithmetic and control circuitry which results in roughly 5 mm/sup 2/ silicon area. Overall performance is sufficient to compose more than 5 full-screen VOPs with a background of size 704/spl times/576 each at 30 Hz.