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Title:STISKANJE IN REKONSTRUKCIJA RASTRSKIH PISAV Z VERIŽNO KODO
Authors:Globačnik, Timotej (Author)
Žalik, Borut (Mentor) More about this mentor... New window
Files:.pdf DR_Globacnik_Timotej_2011.pdf (5,27 MB)
 
Language:Slovenian
Work type:Dissertation (m)
Organization:FERI - Faculty of Electrical Engineering and Computer Science
Abstract:V doktorski disertaciji predstavimo nov način stiskanja rastrskih računalniških pisav, ki je primeren predvsem za nizkozmogljive računalniške sisteme. Postopek stiskanja temelji na tehniki ogliščne verižne kode v kombinaciji s Huffmanovim kodirnikom. Pri tem obliko posameznega znaka pisave predstavimo z verižno kodo, katere elemente dodatno stisnemo s Huffmanovim kodirnikom. Pri postopku rekonstrukcije znakov nastale luknje zapolnimo z algoritmom FloodFill. Ta omogoča omejevanje porabe pomnilnika med postopkom polnjenja lukenj in je zato primeren tudi za uporabo v vgrajenih sistemih. Prostorsko in časovno učinkovitost predlaganega postopka smo primerjali z najbolj razširjenimi postopki predstavitve rastrskih pisav in najpogosteje uporabljenimi postopki stiskanja bitnih slik. Analizo smo izvedli na več vrstah pisav različnih velikosti, pri čemer se je predlagani postopek izkazal kot prostorsko in časovno najučinkovitejši. Prav tako smo na laboratorijskem vgrajenem sistemu implementirali postopek rekonstrukcije znakov in časovno zahtevnost le-tega primerjali z nekaterimi postopki stiskanja bitnih slik. Tudi v tem primeru se je naš postopek izkazal kot najučinkovitejši. Na osnovi rezultatov opravljenih meritev, tako na osebnem računalniku kot na laboratorijskem vgrajenem sistemu, smo potrdili postavljene hipoteze. Glede na ugotovitve lahko zaključimo, da je predstavljeni postopek stiskanja rastrskih pisav zaradi prostorske in časovne učinkovitosti ter enostavne implementacije postopka rekonstrukcije primeren za uporabo v nizkozmogljivih računalniških sistemih.
Keywords:računalniške pisave, rastrske pisave, stiskanje pisav, rekonstrukcija pisav, verižna koda, ogliščna verižna koda, Huffmanovo kodiranje, brezizgubno stiskanje, stiskanje bitnih slik, vgrajeni sistemi, pisave v vgrajenih sistemih
Year of publishing:2011
Publisher:[T. Globačnik]
Source:Topolšica
UDC:004.932.75'1.021(043.3)
COBISS_ID:257502464 Link is opened in a new window
NUK URN:URN:SI:UM:DK:1QBUU65A
Views:1710
Downloads:125
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Categories:KTFMB - FERI
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Secondary language

Language:English
Title:An algorithm for compression and reconstruction of raster fonts using chain codes
Abstract:In this doctoral thesis, a new raster font compression technique for embedded systems is presented. The new approach is based on the combination of the vertex chain code and the Huffman coding algorithm. The outline of each character is defined by the vertex chain code and further compressed by Huffman coding algorithm. During the reconstruction of the characters, the remaining holes are filled using the FloodFill algorithm. This algorithm is improved to limit the memory consumption during the filling process. The spatial and computational analysis of the proposed technique has been carried out on different font types and sizes. The results of the proposed approach have been compared to nowadays the most widely used bi-level image compression techniques and the well-known raster font compression formats. Acquired results show that the proposed approach achieves the highest compression ratios for all font types and sizes. Additionally, the computational requirements are lower than at the techniques existing up to date. To prove the low spatial and computational demands, the reconstruction process has been implemented on the laboratory embedded system. Once more, our technique proved to be the most efficient. As a consequence of acquired results, the set of hypotheses has been confirmed. Therefore, due to the low spatial and computational requirements and rather simple implementation of reconstruction process, the proposed approach is ideal to be used on embedded systems.
Keywords:computer fonts, raster fonts, font compression, font reconstruction, chain code, vertex chain code, Huffman coding, lossless compression, bitmap compression, embedded systems, fonts for embedded systems


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