In the field of computer graphics and 3-D visual communicatins, the ray-based representation of 3-D scene/object has been examined. Since perspective projections, provided by normal lenses, are not suitable for sampling light ray data, the authors have developed a capturing system using a telecentric lens, which provides orthogonal projections of objects. This paper will discuss the implementation and the error measurement of the system. Furthermore, experimental results show the applicability of the system for acquiring light ray data as orthogonal projections and synthesizing arbitrary views.
A deta-driven segmentation algorithm based on a multi-dimensional histogram is proposed for color images. An image is observed as a mixture of multi-variate data, but the number of clusters in the mixture is generally unknown. The proposed algorithm determines the width of a histogram to use and then obtains the number of clusters according to the observed multivariate data. Next, the statistics for each cluster are computed, since this is a requisite for clustering all of the other elements. The proposed clustering method can be applied to various kinds of images, because it is not restricted by an image model used in model-based approaches. The effectiveness of the algorithm is evaluated by computer simulation, and the algorithm is applied to real color image clustering.
The lossless(reversible)discrete cosine transform(DCT) is a very useful transform because it can realize easily an unified lossy/lossless image coding with a compatibility with conventional scheme such as JPEG and MPEG. But on conventional transform coding based on lossless DCT, its compression performance at high-bit rate coding is poorer at high-bit rate coding and it can't ensure the quantity of the maximum error of recovered image. We propose a new transform coding based on lossless DCT in this report. Proposed method can solve the problem in conventional method.
In this report, we propose the "lossless coding gain" as a new objective criterion to theoretically evaluate performance of the lossless wavelet transforms(LWT). Relationship between the "lossless coding gain" and existing "coding gain(lossy coding gain)" is also explicitly described. It becomes possible to theoretically evaluate lossless-lossy unified coding methods based on the LWT under the unified criterion- "lossless coding gain" and "lossy coding gain". Experiments in the report include applications of the two-dimensional(2D)LWT to some standard images and 2D AR(1)model. Effectiveness of the "optimum bit allocation" in the quantization procedure is also described.
In this report, we describe our new video retrieval interface called Color Bar Interface, which features compact color icons visualizing features of video segments and closer coupling with networked video delivery. It is confirmed that Color Bar Inteface provides users with a quick and iterative browsing function even in the environment with limited display space.