Thesis (PhD (Agric))--University of Stellenbosch, 2003. / ENGLISH ABSTRACT: Downgrading of fruit due to insufficient red colour has limited the profitability of lucrative blushed pear cultivars (Pyrus communis L.). In 'Rosemarie', poor fruit colour has been ascribed to pre-harvest red colour loss during periods of high temperature. The regulation of colour development in pears has not been studied and, in addition, little is known about anthocyanin degradation in attached fruit. Changes in colour were recorded and phenylalanine ammonia-lyase (PAL) and UDPGalactose: flavonoid-3-0-glycosyltransferase (UFGT) activities assessed in response to cold fronts and during fruit development in order to establish the regulation of colour development in red and blushed pear cultivars. Best red colour was generally attained a month or more before harvest whereafter red colour faded towards harvest. Unlike in some other fruits, UFGT activity apparently did not limit colour development whereas fading of red colour towards harvest might relate to decreasing PAL activity. 'Rosemarie' colour fluctuated considerably, increasing with cold fronts and decreasing during intermittent warmer periods, while red colour was more stable in other cultivars. PAL and UFGT activities in 'Rosemarie' increased in response to low temperatures, but were unaffected in 'Bon Rouge'. We concluded that anthocyanin synthesis in 'Rosemarie' requires low temperatures while colour development in 'Bon Rouge' and probably also other cultivars is primarily regulated by endogenous factors. Detached pome fruit were used to study temperature and light effects on anthocyanin degradation and fruit colour and to assess the modifying effect of anthocyanin concentration on colour loss. Anthocyanin degradation and red colour loss increased linearly between 10°C and 30°C. Irradiation further increased the rate of degradation and colour loss. The rate of colour loss depended on anthocyanin concentration, being much faster in fruit with high compared to fruit with low pigment levels. This was ascribed to the exponential relationship between anthocyanin concentration and hue at high pigment levels and the linear relationship at lower pigment levels. Anthocyanin degradation and pre-harvest red colour loss in 'Rosemarie' was quantitatively confirmed and corresponded with a warm period during fruit development. Based on these data, we attributed the susceptibility of 'Rosemarie' to pre-harvest colour loss to low anthocyanin concentrations in its peel that allow the visualisation of net anthocyanin degradation at high temperatures. Overhead evaporative cooling (EG) as measure to improve red colour in blushed pears was evaluated. 'Rosemarie' fruit that received pulsed EG applications from two weeks before harvest at air temperatures exceeding 28°G were redder than control fruit at harvest. EG had no effect on 'Forelle' colour. Though EG could be used to improve 'Rosemarie' fruit colour in warm production areas, its effect was relatively small compared to colour change in response to temperature. Lastly, we assessed the photoprotective function of anthocyanin in pear peel. Photoinhibition was evident in exposed faces of pears under natural conditions. The extent of photoinhibition increased with decreasing redness of peel and was maintained after photoinhibitory treatment. Although anthocyanin was apparently able to afford photoprotection at 40oG, we argued against this as a general function. There were indications that photoprotection was associated, but not necessarily due to light attenuation by anthocyanin. / AFRIKAANSE OPSOMMING: Afgradering van vrugte vanweë onvoldoende rooi kleur beperk die winsgewendheid van blospeercultivars (Pyrus communis L.). In die geval van 'Rosemarie' word swak kleur toegeskryf aan vooroes rooikleurverlies gedurende warm periodes. Die regulering van kleurontwikkelling in pere is nog nie ondersoek nie terwyl min bekend is oor antosianiendegradasie aan die boom. Om die regulering van kleurontwikkelling in rooi- en blospeercultivars vas te stel, is veranderinge in kleur en in die aktiwiteit van fenielalanien ammonia-liase (FAL) en UDPGalaktose: flavonoied-3-o-glikosieltransferase (UFGT) gemeet gedurende vrugontwikkelling en in reaksie op koue fronte. Pere was op hul rooiste 'n maand of langer voor oes. Hierna het rooi kleur afgeneem tot met oes. Anders as in sommige ander vrugsoorte het UFGT aktiwiteit nie kleurontwikkeling beperk nie. Die afname in rooi kleur tot met oes mag egter verband hou met 'n gelyktydige afname in FAL aktiwiteit. 'Rosemarie' kleur het aansienlik gefluktueer in reaksie op temperatuur. Rooi kleur het toegeneem met koue fronte en afgeneem in die warmer periodes tussen fronte. Rooi kleur was meer stabiel en klaarblyklik minder afhanlik van lae temperature in ander peercultivars. Die noodsaaklikheid van lae temperature vir kleurontwikkelling in 'Rosemarie' is bevestig deur 'n toename in ensiemaktiwiteit in reaksie op koue fronte. Lae temperature het geen effek gehad op ensiemaktiwiteit in 'Bon Rouge' nie. Appels en pere is gebruik om die effek van temperatuur en lig op antosianiendegradasie en vrugkleur te ondersoek. Die modifiserende effek van antosianienkonsentrasie op kleurverlies is ook ondersoek. Antosianiendegradasie en rooi kleurverlies het lineêr toegeneem tussen 10° en 30°C. Beligting het degradasie en kleurverlies verder versnel. Die tempo van kleurverlies was afhanklik van antosianienkonsentrasie. Kleurverlies was aansienlik vinniger in vrugte met hoë pigmentvlakke, in vergelyking met vrugte met lae pigmentvlakke vanweë die eksponensiële verwantskap tussen antosianienkonsentrasie en kleurskakeringswaardes (hue values) by hoë pigmentvlakke en die lineêre verwantskap by lae pigmentvlakke. Antosianiendegradasie en vooroes rooikleurverlies in 'Rosemarie' is kwantitatief bevestig en het saamgeval met 'n warm periode tydens vrugontwikkelling. Gebaseer op hierdie data is die gevoeligheid van 'Rosemarie' vir vooroes rooikleurverlies toegeskryf aan lae antosianienkonsentrasies wat die sigbaarheid van netto antosianiendegradasie by hoë temperature verhoog. Die gebruik van oorhoofse evaporatiewe verkoeling (EG) om rooi kleur van blospere te verbeter is ge-evalueer. 'Rosemarie' vrugte wat evaporatief verkoel is bo 28°G vanaf twee weke voor oes, was rooier as kontrole vrugte by oes. 'Forelle' kleur het nie gereageer op EG nie. Die effek van EG op vrugkleur was relatief klein in vergelyking met die effek van temperatuur. AI kan EG 'Rosemarie' kleur verbeter in warm produksiestreke sou dit meer effektief wees om 'Rosemarie' se verbouing te beperk tot koeler klimaatstreke. Laastens is die vermoë van antosianien om peerskil teen fotoinhibisie te beskerm ondersoek. Fotoinhibisie was aanwesig in vrugskil wat direk blootgestel was aan sonlig in die boord. Die omvang van fotoinhibisie het toegeneem met 'n afname in rooi pigmentasie van vrugskil. Die verband tussen skilkleur en fotoinhibisie was steeds aanwesig na blootstelling aan ligstres by 10° en 400G. Ons het egter geredeneer teen 'n algemene funksie vir antosianien in fotobeskerming by hoë temperature. Verder was daar aanduidings dat, alhoewel geassossieer met rooi skilkleur, beskerming teen ligstres nie noodwendig te wyte was aan antosianien nie.

Thesis (MscAgric (Viticulture and Oenology))--University of Stellenbosch, 2006. / Under certain South African conditions, Redglobe develops a colour that is too dark and thus unacceptable for the Far Eastern markets. These markets require a pink colour instead of a dark red colour. The cultivation of grapes with an acceptable colour involves amongst other, canopy management practices. This generally includes the removal of leaves and/or lateral shoots. Hereby, the leaf area and the microclimatic conditions in the canopy are altered. The aim of this study was to test the usefulness of leaf and lateral shoot removal at different defoliation times after anthesis in order to obtain a pink coloured Redglobe crop. Other quality aspects, namely total soluble solids (TSS), total titratable acidity (TTA), berry mass and total yield, were also evaluated. A canopy management trial was conducted on six year old Redglobe vines with moderate vigour. The treatment design was a 2 x 3 x 4 factorial and involved two leaf removal (L) levels (L0 = 0% leaf removal; L33 = 33% leaf removal) in combination with three lateral shoot removal (LS) levels (LS0 = 0 % lateral shoot removal; LS50 = 50% lateral shoot removal; LS100 = 100% lateral shoot removal). Four defoliation times (DT) were selected: 36 (pea berry size), 69 (véraison), 76 (one week after véraison) and 83 (two weeks after véraison) days after anthesis (DAA). A total of 24 treatment combinations, replicated in four blocks, were applied. Generally, treatment combinations involving 33% leaf removal lowered the main shoot leaf area. Likewise, the lateral shoot leaf area was decreased by increasing levels of lateral shoot removal at any defoliation time. As expected, 33% leaf removal applied in combination with any level of lateral shoot removal, always resulted in a lower total vine leaf area compared to where 0% leaf removal was part of the treatment combination. Compensation reactions occurred and in this regard the main shoot leaf size increased due to 33% leaf removal applied at 1 week after véraison and 2 weeks after véraison. Treatment combinations involving lateral shoot removal increased the ratio of main shoot leaf area to the total leaf area. On the other hand, the main shoot leaf area percentage was lowered by the application of 33% leaf removal at 2 weeks after véraison compared to no leaf removal at the same defoliation time. It can therefore be assumed that the contribution of lateral shoot leaves to grape composition might have increased in cases where the main shoot leaf area was lowered at a later stage (e.g. 2 weeks after véraison). The bunches were visually evaluated and divided into classes from dark (class one) to light (class nine). This visual bunch evaluation showed that the mean bunch colour was in class three (lighter than class two) due to the defoliation time. The lateral shoot removal x leaf removal interaction resulted in a mean bunch colour that was in classes 2 and 3. However, within these classes, there was a tendency that bunch colour decreased for defoliation times later than pea berry size. The lateral shoot removal x leaf removal interactions showed that bunch colour was darker when the treatment combinations involved 0% leaf removal. The percentage of bunches with the desired colour was increased by application of the treatments at véraison, compared to the other defoliation times, and also with 50% lateral shoot removal and 100% lateral shoot removal compared to 0% lateral shoot removal. Biochemical analyses confirmed that increased levels of lateral shoot removal generally lowered the anthocyanin concentration regardless of defoliation time. A similar effect on TSS was observed, i.e. from véraison onwards, the application of 50% lateral shoot removal and 100% lateral shoot removal tended to lower TSS. The effect of these levels of lateral shoot removal at véraison was significant. The role of the lateral shoots in colour development and sugar accumulation is therefore emphasized. Furthermore, the special role that lateral shoots also play in berry development is illustrated in that berry mass tended to decrease when 100% lateral shoot removal in combination with 33% leaf removal and 100% lateral shoot removal in combination with 0% leaf removal were applied at véraison. This, together with the positive relationship obtained between grape colour and the lateral shoot leaf area:fruit mass ratio, accentuates the role of active leaf area during the ripening period. The possible effect of the microclimatic light environment on colour must also be considered. However, although the light intensity increased with increased levels of LS, the colour that was obtained was probably not associated with the differences in light intensity. It was found that it is possible to manipulate the colour of Redglobe grapes with defoliation treatments. However, the treatments that have a decreasing effect on grape colour also affected other quality parameters like TSS and berry size negatively. Although, it is possible to reduce the colour of Redglobe through the application of leaf and lateral shoot removal at different defoliation times, the question arises whether the treatment combinations used in this study are worthwhile to pursue because the mean bunch colour that was obtained was still too dark. However, it was possible to increase the percentage of bunches with the desired colour. Therefore, if such treatments are applied, it must be approached cautiously, keeping in mind that assimilate supply has to be sustained throughout the ripening period.

<p>Print quality (PQ) is one of the most significant issues with electrophotographic printers. There are many reasons for PQ issues, such as limitations of the electrophotographic process, faulty printer components, or other failures of the print mechanism. These reasons can produce different PQ issues, like streaks, bands, gray spots, text fading, and color fading defects. It is important to analyze the nature and causes of different print defects to more efficiently repair printers and improve the electrophotographic process. </p> <p><br></p> <p>We design a general framework for print quality detection and analysis of customer content. This print quality analysis framework inputs the original digital image saved on the computer and then the scanned image. This framework includes two main modules: image pre-processing, print defects feature vector extraction, and classification. The first module, image pre-processing, includes image registration, color calibration, and region of interest (ROI) extraction. The ROI extraction part is designed to extract four different kinds of ROI from the digital master image. Because different ROIs include different print defects, for example, the symbol ROI includes the text fading defect, and the raster ROI includes the color fading defect. The second module includes different ROI print defects detection and analysis algorithms. We classify different ROI print defects using their feature vector based on their severity. This module proposed four important defects detection methods: uniform color area streak detection, symbol ROI color text fading detection, raster ROI color fading detection using a novel unsupervised clustering method, and raster ROI streak detection. We will introduce the details of these algorithms in this thesis. </p> <p><br></p> <p>We will also show two other interesting print quality projects: print margin skew detection and print velocity simulation and estimation. Print margin skew detection proposes an algorithm that uses the Hough Lines Detection algorithm to detect printing margin and skew errors based on factual scanned image verification. In the print velocity simulation and estimation project, we propose a print velocity simulation tool, design a specific print velocity test page, and design a print velocity estimation algorithm using the dynamic time warping algorithm. </p>