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Image Bit-Depth Expansion Method Based On Sparse
Representations
Záviška, Pavel
In this paper, a method for restoration of low bit-depth images based on sparse representations is presented. Proposed method is independent on the transform used, however for the purposes of experiments, Discrete Cosine Transform (DCT) and Discrete Wavelet Transform (DWT) are used. The experiments show that our method enhances the visual quality of low bit-depth images and performs better, in terms of PSNR, than basic bit-depth expansion methods.
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Applications supporting lectures on colour models
Khaladzinski, Kiryl ; Záviška, Pavel (referee) ; Rajmic, Pavel (advisor)
The aim of this bachelor thesis is to create Web applications that show the possibilities of working with different color models in real examples shows principles of digital images creation and the possibility of processing digital image data. Theoretical part devoted to the basic concept in color theory and the basis of raster images. The practical part is the design of four applications and their creation. The first of the applets shows the principle of mixing colors in different color models, the second on the example shows the basis of the index representation of the image, the third shows the methods of translating the color image to grayscale and the last applet is used to translate grayscale image to color image.
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Search for a dictionary for audiosignals
Martinek, Václav ; Záviška, Pavel (referee) ; Rajmic, Pavel (advisor)
This thesis should answer what constitutes audiosignal. It deals with the dictionary learning based on sparse representations of signals. This thesis describing algorithms, which are important for the creation of learning dictionaries. We find a comparison of signal representation using Fourier transform and learned vocabulary. It describes the creation of a database of musical sounds.
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Applications supporting lectures on colour models
Khaladzinski, Kiryl ; Záviška, Pavel (referee) ; Rajmic, Pavel (advisor)
The aim of this bachelor thesis is to create Web applications that show the possibilities of working with different color models in real examples shows principles of digital images creation and the possibility of processing digital image data. Theoretical part devoted to the basic concept in color theory and the basis of raster images. The practical part is the design of four applications and their creation. The first of the applets shows the principle of mixing colors in different color models, the second on the example shows the basis of the index representation of the image, the third shows the methods of translating the color image to grayscale and the last applet is used to translate grayscale image to color image.
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Tool for subjective quality evaluation of audiosignals restoration
Černý, Viktor ; Dorazil, Jan (referee) ; Záviška, Pavel (advisor)
Bacherol thesis deals with the theory of audio signal depreciation and reconstruction, with objective tests and subjective methods of reconstructed signal evaluation. At first, there are described several types of depreciation of audio signals and then reconstruction types for their reconstruction. After the reconstruction, types six objective and six subjective tests are mentioned for the evaluation of audio signal quality. The next part of the Bachelor thesis is the description of the program that was implemented in the programming language Java. The program is designed to design MOS, MUSHRA and ABX listening tests as well as to use for the actual testing. At the end of the thesis are the results of the listening tests that were used to test the program and the user ratings of the application.
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Search for a dictionary for audiosignals
Martinek, Václav ; Záviška, Pavel (referee) ; Rajmic, Pavel (advisor)
This thesis should answer what constitutes audio signal. It deals with the dictionary learning based on sparse representations of signals. This thesis describing algorithms, which are important for the creation of learning dictionaries. We find a comparison of signal representation using Fourier transform and learned vocabulary. It describes the creation of a database of musical sounds.
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Restoration of signals after passing through the limiter with the use of psychoacoustic model
Kramář, Denis ; Rajmic, Pavel (referee) ; Záviška, Pavel (advisor)
This bachelor thesis deals with the use of sparse representaions for the purpose of restoration clipping-damaged audiosignal. First, a theory of limiter and signal limiting itself is discussed. Subsequently, some of present methods based on sparse representations theory are given. The theory of sparse representations is discussed in following chapture. After that is here described a psychoacoustic model and it's use for declipping. At the end of theoretical part, two methods dealing with this problem are introduced. First is based on synthesis model of signal using Douglas-Rachford algorithm. Second is based on analysis signal model using Chambolle-Pock algorithm. In the next part is their implementation in the Matlab environment. Finally, the result achieved by both algorithms are evaluated.
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Audio restoration based on sparse signal representations
Záviška, Pavel ; Průša, Zdeněk (referee) ; Rajmic, Pavel (advisor)
This Master's Thesis deals with the issue of audio clipping and the application of sparse represenations model for the task of declipping. First, a general theory of clipping is described, followed by a brief overview of existing methods and a description of the general theory concerning sparse representations of signals and bases, respectively frames. Subsequently, two methods solving declipping problem based on sparse representations are intruduced. The first method uses the Generic proximal algorithm for convex optimization, the second one uses the Douglas-Rachford algorithm. The above mentioned methods have been programmed in the Matlab environment. The results of the declipping methods are evaluated according to SNR, PEMO-Q and also by subjective listening tests.
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Methods for increasing bit-depth in images
Záviška, Pavel ; Koldovský, Zbyněk (referee) ; Rajmic, Pavel (advisor)
The goal of this bachelor thesis is the application of an issue of sparse representations on the task of increasing bit-depth in images. Standard methods for bit-depth expansion are described, subsequently a method using sparse representation of an image signal is introduced. Methods are programmed in the Matlab enviroment. The results of the methods implemented are compared by using PSNR, SSIM objective indexes and subjectively using an online questionnaire.
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