Browsing by Author "Liu, Kai"

Now showing 1 - 2 of 2

Open Access
Development of TOSCA service templates for provisioning portable IT services
(2013) Liu, Kai
Provisioning cloud computing solutions is a tedious and long process, especially when configuring many components and not only offering the application but also the infrastructure. Today, an administrator has to upload, install and configure all the components of a software solution manually, which not only takes time and is prone to errors but also increases the onboarding costs at the cloud provider. Decreasing deployment times by the use of an automated system is favored. TOSCA provides a specification which allows the deployment and management of cloud services by providing a meta-model. With that it is possible to mitigate all problems in theory. OpenTOSCA is a framework called container, which can interpret the TOSCA specification and is used in this work to deploy an Enterprise Content Management stack on a cloud environment, testing the boundaries of its capabilities. After designing deployment models by the means of a domain specific modeling approach, an implementation is realized and compiled into a deployment file. This file is also called a container file and is processed by OpenTOSCA to initiate the deployment on the cloud environment, including the necessary middleware. The goal of this diploma thesis is to develop a TOSCA Service Template, that provides a topology model and automates the deployment of ECM core components. TOSCA Node Types for the middleware and application components have to be defined. To further help modeling the topology, a domain specific model (DSM) will be introduced by generically defining all components and their operations. That generic model will be used to realize the actual ECM stack components. The ECM stack is then deployed via OpenTOSCA and the execution is reviewed.
Open Access
A just noticeable distortion based perceptually lossless image compression codec
(2012) Liu, Kai
In this study thesis a JND (Just-Noticeable-Distortion)-Measurement will be implemented on top of JPEG-LS while only considering a grayscale bit depth of 8 Bit. This is sufficient to show a proof of concept of combining the JND approach with JPEG-LS. JPEG-LS is a widely used and relatively simple coding mechanism for lossless and near-lossless image compression. The JND measurement will be defined, implemented and integrated into JPEG-LS. Therefore a modified approach of [CL95] will be used. The quantization step size (QSS) will be adapted dynamically according to the JND value so that the compression ratio compared to a standard JPEG-LS implementation can be improved. By that, a near-lossless variable bit-rate (VBR) is introduced into the coding flow. The encoder and decoder are implemented in MATLAB and after defining the visual quality criteria the results are evaluated and analysed in matter of compression quality and performance. Two test picture sets are used and the perceptual quality of the codec will be evaluated by an Mean-Opinion-Score (MOS) test and Multi-Scale Structural Similarity (MS-SSIM) test.