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Parallel signal processing with help of GPU
Václavík, Jiří ; Frýza, Tomáš (referee) ; Mego, Roman (advisor)
In the introduction, the bachelor thesis outlines the origins of modern graphic processors. The theoretical part of the text describes the minimum of required information from parallel programming model essential to program simple DSP algorithms. The next part elaborate on three common DSP algorithms, finite impulse response filter, naive implementation of discrete cosine transform type II, and fast Fourier transform. To demonstrate parallel capability of GPU, algorithm for JPEG compression was chosen as JPEG compression is favorable because it illustrates both advantages and disadvantages of parallel data processing on GPU, and compromises needed to be considered.
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Effect of Noise on Image Compression
Pavlík, Jiří ; Svoboda, Pavel (referee) ; Bařina, David (advisor)
This thesis examines effect of different types of noise on performance of significant image compression formats. Three different types of noise are examined, Gaussian noise, Gaussian noise with bigger granularity and shot noise. Two older loosy image compression formats JPEG and JPEG 2000 are compared with newer format WebP. This examination is based on results of experiments with images, which are intentionally degraded by noise, then compressed to examined formats and compared with result of experiments for original images without noise. The effect of noise on performance of comparised formats is based on image quality metric SSIM. From results of experiments, Gaussian noise with bigger granularity seems to be the least distruptive from all types of noises. The other two types of noise have much more dwindling effect on quality of images.
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Analysis of JPEG 2000 Settings
Vrtělová, Lucie ; Klíma, Ondřej (referee) ; Bařina, David (advisor)
This thesis is focused on analysis of JPEG 2000 settings. The aim of this thesis is to explore and compare each settings and different implementation. The analysis was done with two libraries, which implements JPEG 2000 - Kakadu and OpenJPEG. Data was processed by framework written in Python3. Created solution provides comprehensive view on using each settings of JPEG 2000 on specific data. Results of this thesis allow faster using of JPEG 2000 on specific data.
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Digital Image Steganography
Kolarčík, Tomáš ; Šimek, Václav (referee) ; Strnadel, Josef (advisor)
This bachelor thesis deals with digital image steganography and implements some of the available methods. This thesis describes steganography on a general level, it's history and it's current form. It also shows it's classification according to the type of carrier, the classification of the methods according to the style of hiding data and the influence of the hidden information. The primary subject of this thesis is image steganography, where facts that allow imperceptibly hide data inside image are described. A great part of this thesis is dedicated to the characteristics of the methods, which we observe and to the methods themselves. All of the methods described are implemented in a graphical and console application. The created application provides multiple image formats for hiding. In the last part, testing is performed in terms of capacity, imperceptibility and robustness.
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Image compression in interactive applications in digital video broadcasting
Bodeček, Kamil ; Vrba, Kamil (advisor)
Compressed images are used very frequently in interactive applications in digital video broadcasting. New methods increasing efficiency of the image transmission in digital video broadcasting networks are proposed. Adaptive spatial filtering methods have been proposed for enhancement of the visual perception of the compressed images. New optimalization method is based on application of the filtering algorithms on more compressed images (data size are reduced). Visual quality enhancement is processed in interactive application. Further, new compression methods JPEG2000 and H.264 for image compression have been analysed. Novel compound image compression method for standard and high spatial television resolution is proposed in the thesis.
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Digital Image Steganography
Mazánek, Antonín ; Šimek, Václav (referee) ; Strnadel, Josef (advisor)
This bachelor's thesis introduces the steganography scientific discipline. It presents its ancient and relative recent history, mentions its current use and outlines the possible directions for steganography future. It introduces steganography into context of hiding information superior domain and highlights differences between other methods in this domain. It describes steganography subdivisions and closer deals with digital image steganography. It presents some known methods and types of digital image data. The thesis also contains more detailed description of image data in PNG format. It describes the implementation of LSB and PVD steganography methods with images in PNG format as cover object and evaluates their key properties, namely: imperceptibility, capacity and robustness. At the end of the thesis, the author's reflection on the results and possibilities of further modifications of the mentioned methods is given.
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Lossy Video Compression
Šiška, Michal ; Průša, Zdeněk (referee) ; Schimmel, Jiří (advisor)
This thesis deals with description of lossy video compression. Theoretical part of the work describes the fundamentals of the video compression and standarts for lossy as well lossless video and still image compression. The practical part follows up with design of Java program for simulation of MPEG codec.
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Accelerated JPEG Decompression on Graphics Processing Units
Janošík, Ondřej ; Polok, Lukáš (referee) ; Pečiva, Jan (advisor)
This thesis addresses the issue of JPEG decompression, design of algorithms for decompression on graphics cars and their implementation. In more details, it describes specific process of implementation, including possible alternatives and optimizations. It is described in order of JPEG decompression algorithm steps. The aim of this thesis is the reduction of time consumed by uplading textures into graphics unit’s memory using JPEG compressed textures and decompression od the side of graphics card. In addition to time savings, this access reduces processor load, which may be in some cases beneficial.
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Lossy Light Field Compression
Dlabaja, Drahomír ; Milet, Tomáš (referee) ; Bařina, David (advisor)
The aim of this paper is to propose, implement and evaluate a new lossy compression method for light field images. The proposed method extends the JPEG method to four dimensions and brings new ideas which lead to better compression performance. Correlation between light field views is exploited in both dimensions by four-dimensional discrete cosine transformation. The lossy part of the encoding is performed by quantization, similarly to the JPEG method. The proposed method is implemented as a program library in a C++ language. This paper compares the proposed method to JPEG, JPEG 2000 and HEVC intra image compression methods and HEVC video compression method. The results show that the proposed method outperforms the reference methods with images with a higher amount of views. HEVC video method is better for images with fewer views or for very low bitrates.
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