Thesis (MEng)--Stellenbosch University, 2000. / ENGLISH ABSTRACT: The purpose of this thesis is to investigate the nature of digital image compression
and the calculation of the quality of the compressed images. The work is focused on
greyscale images in the domain of satellite images and aerial photographs. Two
compression techniques are studied in detail namely the JPEG and fractal
compression methods. Implementations of both these techniques are then applied to
a set of test images. The rest of this thesis is dedicated to investigating the
measurement of the loss of quality that was introduced by the compression. A
general method for quality measurement (signal To Noise Ratio) is discussed as well
as a technique that was presented in literature quite recently (Grey Block Distance).
Hereafter, a new measure is presented. After this, a means of comparing the
performance of these measures is presented. It was found that the new measure for
image quality estimation performed marginally better than the SNR algorithm. Lastly,
some possible improvements on this technique are mentioned and the validity of the
method used for comparing the quality measures is discussed. / AFRIKAANSE OPSOMMING: Die doel van hierdie tesis is om ondersoek in te stel na die aard van digitale
beeldsamepersing en die berekening van beeldkwaliteit na samepersing. Daar word
gekonsentreer op grysvlak beelde in die spesifieke domein van satellietbeelde en
lugfotos. Twee spesifieke samepersingstegnieke word in diepte ondersoek naamlik
die JPEG en fraktale samepersingsmetodes. Implementasies van beide hierdie
tegnieke word op 'n stel toetsbeelde aangewend. Die res van hierdie tesis word dan
gewy aan die ondersoek van die meting van die kwaliteitsverlies van hierdie
saamgeperste beelde. Daar word gekyk na 'n metode wat in algemene gebruik in die
praktyk is asook na 'n nuwer metode wat onlangs in die literatuur veskyn het. Hierna
word 'n nuwe tegniek bekendgestel. Verder word daar 'n vergelyking van hierdie
mates en 'n ondersoek na die interpretasie van die 'kwaliteit' van hierdie
kwaliteitsmate gedoen. Daar is gevind dat die nuwe maatstaf vir kwaliteit net so goed
en selfs beter werk as die algemene maat vir beeldkwaliteit naamlik die Sein tot Ruis
Verhouding. Laastens word daar moontlike verbeterings op die maatstaf genoem en
daar volg 'n bespreking oor die geldigheid van die metode wat gevolg is om die
kwaliteit van die kwaliteitsmate te bepaal
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/51796 |
| Date | 04 1900 |
| Creators | Nolte, Ernst Hendrik |
| Contributors | Boshoff, Hendrik, Lourens, Johan, Stellenbosch University. Faculty of Engineering. Dept. of Electrical and Electronic Engineering. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | Unknown |
| Type | Thesis |
| Format | 87 p. : ill. |
| Rights | Stellenbosch University |
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