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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.


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Patent
Tokumoto Hirokazu1
19 Jun 2018
TL;DR: In this article, an image processing apparatus includes an acquisition unit configured to acquire a bitmap image in which each of contained pixels has an alpha value indicating opacity of this pixel, and a rendering unit config to render the image.
Abstract: An image processing apparatus includes an acquisition unit configured to acquire a bitmap image in which each of contained pixels has an alpha value indicating opacity of this pixel, and a rendering unit configured to render the bitmap image. The rendering unit is configured to, when rendering the bitmap image, refrain from performing alpha blending on a pixel contained in the bitmap image that has a specific alpha value and perform the alpha blending on a pixel contained in the bitmap image that has a different alpha value from the specific alpha value.

6 citations

Proceedings ArticleDOI
Jung-Hwan Kim1, Sun-Kyu Kim1, Tae-Min Lee1, Yong-Jin Lim1, Joonhong Lim1 
01 Nov 2018
TL;DR: The proposed mapping method, which combines planar and hemispherical projection method, makes it possible to see around the vehicle at various viewpoints of 360-degree and may be useful for safe driving and accurate accident investigation.
Abstract: Most current vehicle black boxes with AVM (Around View Monitoring) function provide a bird's-eye view of 2D type. This viewpoint is a form of looking at the vehicle from above so that it gives the driver a sense of spatial heterogeneity. In addition, the top-view type has a limited viewing angle, which makes it difficult to conduct an accident investigation, parking and so on. To solve these problems, we propose the 3D A VM algorithm using image composition of multi-channel cameras in this paper. The proposed 3D AVM algorithm is divided into three stages. In the first stage, we perform distortion correction of wide-angle lens and perspective transform. The image stitching, white balance and alpha blending are made in the second stage. The 3D texture mapping is executed in the final stage. This proposed mapping method, which combines planar and hemispherical projection method, makes it possible to see around the vehicle at various viewpoints of 360-degree. The experimental study results indicate that the proposed method overcome the disadvantages of the 2D AVM black boxes and may be useful for safe driving and accurate accident investigation.

6 citations

Journal ArticleDOI
TL;DR: It is shown, that generating CT images through the reconstruction of weighting coefficients has the potential to improve the resolution noise trade-off and thus to improved the dose usage in clinical CT.
Abstract: Purpose: Iterative image reconstruction gains more and more interest in clinical routine, as it promises to reduce image noise (and thereby patient dose), to reduce artifacts, or to improve spatial resolution. Among vendors and researchers, however, there is no consensus of how to best achieve these aims. The general approach is to incorporatea priori knowledge into iterative image reconstruction, for example, by adding additional constraints to the cost function, which penalize variations between neighboring voxels. However, this approach to regularization in general poses a resolution noise trade-off because the stronger the regularization, and thus the noise reduction, the stronger the loss of spatial resolution and thus loss of anatomical detail. The authors propose a method which tries to improve this trade-off. The proposed reconstruction algorithm is called alpha image reconstruction (AIR). One starts with generating basis images, which emphasize certain desired image properties, like high resolution or low noise. The AIR algorithm reconstructs voxel-specific weighting coefficients that are applied to combine the basis images. By combining the desired properties of each basis image, one can generate an image with lower noise and maintained high contrast resolution thus improving the resolution noise trade-off. Methods: All simulations and reconstructions are performed inmore » native fan-beam geometry. A water phantom with resolution bar patterns and low contrast disks is simulated. A filtered backprojection (FBP) reconstruction with a Ram-Lak kernel is used as a reference reconstruction. The results of AIR are compared against the FBP results and against a penalized weighted least squares reconstruction which uses total variation as regularization. The simulations are based on the geometry of the Siemens Somatom Definition Flash scanner. To quantitatively assess image quality, the authors analyze line profiles through resolution patterns to define a contrast factor for contrast-resolution plots. Furthermore, the authors calculate the contrast-to-noise ratio with the low contrast disks and the authors compare the agreement of the reconstructions with the ground truth by calculating the normalized cross-correlation and the root-mean-square deviation. To evaluate the clinical performance of the proposed method, the authors reconstruct patient data acquired with a Somatom Definition Flash dual source CT scanner (Siemens Healthcare, Forchheim, Germany). Results: The results of the simulation study show that among the compared algorithms AIR achieves the highest resolution and the highest agreement with the ground truth. Compared to the reference FBP reconstruction AIR is able to reduce the relative pixel noise by up to 50% and at the same time achieve a higher resolution by maintaining the edge information from the basis images. These results can be confirmed with the patient data. Conclusions: To evaluate the AIR algorithm simulated and measured patient data of a state-of-the-art clinical CT system were processed. It is shown, that generating CT images through the reconstruction of weighting coefficients has the potential to improve the resolution noise trade-off and thus to improve the dose usage in clinical CT.« less

6 citations

Patent
Takashi Ono1
11 Mar 2011
TL;DR: In this article, an apparatus includes an original-document-attribute determining unit that determines attribute of an original document image, a form-attentive determining unit determining attribute of a form image, and a compositing unit that performs sequence of compositing of the original document images, a copy-forgery-inhibited pattern image and the form image.
Abstract: An apparatus includes an original-document-attribute determining unit that determines attribute of an original document image, a form-attribute determining unit that determines attribute of a form image, and a compositing unit that performs sequence of compositing of the original document image, a copy-forgery-inhibited pattern image, and the form image, the sequence of compositing being determined based on the determined attribute of the original document image and the determined attribute of the form image.

6 citations

Proceedings ArticleDOI
01 Jul 2010
TL;DR: Experimental results prove the effectiveness of the proposed authentication method utilizing the secret sharing technique to resist attacks with a data recovery capability for binary document images in PNG format.
Abstract: A new authentication method utilizing the secret sharing technique to resist attacks with a data recovery capability for binary document images in PNG format is proposed. An authentication signal is generated for each block of a cover image, which together with the block content is transformed into several shares using the Shamir secret sharing scheme. The shares then are embedded into the alpha channel plane of the input PNG image in a carefully designed manner. In the process of image authentication, an image block is marked as tampered if the authentication signal computed from the current block content does not match that extracted from the shares embedded in the alpha channel plane. Data recovery is conducted for each tampered block by a reverse Shamir scheme after collecting enough shares from unmarked blocks. Experimental results prove the effectiveness of the proposed method for real applications.

6 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20221
20219
20208
201913
201821
201723