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A STUDY ON VQ BASED COMPRESSION OF HIGH DYNAMIC RANGE IMAGES
Nagisa Sugiyama,Masahiro Okuda 대한전자공학회 2008 ITC-CSCC :International Technical Conference on Ci Vol.2008 No.7
An encoding method of the high dynamic range (HDR) images based on Vector Quantization is discussed. The HDR images have much higher dynamic ranges compared with the low dynamic range (LDR) images. Due to its high dynamic range, the size is often huge, thus development for functional compression is needed. On the other hand, we often need to convert them into the LDR images because the existing output devices cannot directly output the dynamic ranges of HDR images. Our goal is to develop a HDRI compression method that minimizes the error of the tone-mapped LDR images. Therefore we applied the adjustment of scale and the evaluation of the error in the log domain. Our method improves a compression performance, compared to methods that directly apply the conventional vector quantization to the HDR images.
High Dynamic Range Image Watermarking
Fabrizio Guerrini,Masahiro Okuda 대한전자공학회 2008 ITC-CSCC :International Technical Conference on Ci Vol.2008 No.7
High Dynamic Range (HDR) images represent the future format for digital images since they allow more sensitive rendering. However, nowadays special types of preprocessing collectively known as tone mapping operators are needed to adapt HDR images to currently existing displays. Tone mapped images, although of reduced dynamic range, have nonetheless high quality and hence retain some commercial value. In this paper we propose a solution to the problem of HDR watermarking, e.g. for copyright embedding, that should survive tone mapping. Therefore, the requirements imposed on the watermark encompass imperceptibility, a certain degree of security and robustness to tone mapping operators. The proposed watermarking system belongs to the blind, detectable category, it is based on the QIM paradigm and employs a higher order statistic as feature. Preliminary experimental analysis shows positive results; more work is needed and currently underway.
THE PREDICTIVE CODING FOR GEOMETRY IMAGES OF 3D MODELS BASED ON ERROR SENSITIVITY
Xinwei Xue,Masahiro Okuda 대한전자공학회 2008 ITC-CSCC :International Technical Conference on Ci Vol.2008 No.7
In this paper we introduce a predictive coding for the geometry image of 3D models. Based on a fact that in a smooth surface the sensitivity of the error in the normal direction of each vertex is higher than the one in its tangent direction, we propose a predictive coding method for the geometry image. We have compared our proposed method with the conventional method and show that our proposed method is able to decrease the error in the same compressibility.