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Geometric Superresolution for Removal of Undersampling Effect

Thesis Info

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Author

Sohail, Muhammad

Program

PhD

Institute

Pakistan Institute of Engineering and Applied Sciences

City

Islamabad

Province

Pakistan

Country

Pakistan

Thesis Completing Year

2014

Thesis Completion Status

Completed

Subject

Physics

Language

English

Link

http://prr.hec.gov.pk/jspui/bitstream/123456789/2209/1/2763S.pdf

Added

2021-02-17 19:49:13

Modified

2024-03-24 20:25:49

ARI ID

1676726338245

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This dissertation presents work on the Geometric Superresolution. There are two main parameters that can affect Geometric Superresolution, the finite size of pixels and the pitch of the pixels in digital imaging device like CCD (charged coupled device). In superresolution systems, the ultimate limit to resolution generally comes from the Geometric and not from the optical part of an imaging system. This thesis mainly deals with the undersampling of an optical image in which the separation between the neighbouring pixels in a CCD is assumed to be greater than the separation required by Nyquist Sampling. The problem of undersampling an optical image has been dealt with the use of an Optical Mask placed at the Fourier transform plane in a coherent 4f imaging system. The one dimensional version of the Optical Mask consists of a 1-dimensional amplitude grating. The Optical Mask is used to sample the Fourier transform of the input object. Due to the sampled Fourier transform, the image plane contains replicas of the input object. A CCD is used to undersample these replicas. The recorded undersampled image is Fourier transformed and contains replicas of original object spectrum but overlapped due to the undersampled image recorded by CCD. The overlapped spectrum is multiplied with a soft copy of an Optical Mask which removes the overlapping by removing the neighbouring spectral copies. An interpolation is done on the recovered single object spectral copy to fill the holes in the spectrum. The resultant spectrum is then Fourier transformed to obtain an image free of artefacts and free of undersampling effects. Different analogues of Optical Masks and CCD pixels have been presented and discussed in this thesis. Optical Masks may consist of negligibly small line widths or lines with finite widths. Similarly, an ideal CCD may consist of point pixels in which the pixel size is negligible in comparison with the spacing between them or in real situations may have finite size. The effects of these parameters on Geometric Superresolution have been discussed in the thesis. Simulation results in one and two dimensional have been presented to support the idea. A part of the thesis also discusses a technique dealing with subpixeling. An optical image using a Spatial light modulator is projected on a CCD and shifted in subpixel steps. The retrieved data corresponding to each subpixel step is combined to obtain high resolution image. This has been supported with experimental verification.
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فصل پنجم: آیاتِ استفہام میں فہمِ عقیدہ آخرت (تفسیر تدبرِ قرآن کی روشنی میں تخصیصی مطالعہ)

فصل پنجم: آیاتِ استفہام میں فہمِ عقیدہ آخرت (تفسیر تدبرِ قرآن کی روشنی میں تخصیصی مطالعہ)

حیات بعد الممات کا سوال ایک فلسفیانہ سوال نہیں ہے بلکہ اس کا ہمارے عملی زندگی سے بہت گہرا تعلق ہے اگر انسان کو جوابدہ کا احساس نہ ہو تو وہ اپنے اعمال پر کبھی بھی محاسبہ کرنا پسند نہیں کرے گا اس کے اخلاقی تصورات ہی بدل جائیں گے اس کا پورا اخلاقی نظام خود غرضی، بے حسی اور نفسانیت کی بنیاد پر تعمیر ہوگا اس کے برعکس اگر اعمال کی جوابدہی کا تصور ہوگا تو وہ اچھے یا برے انجام کے باعث نتیجے پر غور کرے گا۔جو لوگ قیامت کا انکار کرتے ہیں انکے بارے میں قرآن میں بیان کیا جا رہا ہے:

"وَقَالُوْٓا ءَ اِذَا كُنَّا عِظَامًا وَّرُفَاتًا ءَاِنَّا لَمَبْعُوْثُوْنَ خَلْقًا جَدِيْدًا"۔[[1]]

"اور انہوں نے کہا کہ جب ہم زمین میں گم ہو جائیں گے تو کیا ہم پھر نئے سرے سے پیدا ہونگے؟"

اس آیت میں منکرین قیامت کی روش بیان کی جا رہی ہے کہ وہ لوگ بطور تعجب کے کہتے ہیں کہ ہم مر جائیں گے ہڈیاں بوسیدہ ہو جائیں گی ہمارا وجود مٹی میں مل جائے گا تو دوبارہ کیسے پیدا ہو سکتے ہیں ؟ جبکہ یہ بات واضح ہے کہ جو خالق انکو بغیر کسی ماڈل کے پہلی بار تخلیق کرنے پر قادر ہے تو دوبارہ پیدا کیوں نہیں کر سکتا بلکہ اس کے لئے تو دوبارہ پیدا کرنا بہت ہی آسان بات ہے ۔

"اسلام نے وضاحت فرما دی ہے کہ کارخانہ ہستی کا حدوداربعہ صرف وہی عالم رنگ و بو نہیں ہے جو تمہارے چاروں طرف پھیلا ہوا ہے میدانوں ، کھلیانوں، دریاؤں ، پہاڑوں ،آبشاروں، بادلوں ، آسمان...

حسین بن منصور حلاج اور ان کی صوفیانہ تعلیمات کا علمی وتحقیقی جائزہ

A Sufi poet, teacher and philosopher, Hallaj was executed on the orders of an Abbasside caliph for uttering these words, taken to mean Hallaj as claiming himself to be God. After more than a decade of imprisonment, Hallaj was eventually executed publically in Baghdad in the year 922. He is seen by many as a revolutionary writer and teacher of his time, when practices of mysticism were not meant to be shared publically. Yet he remains a controversial figure, revered by Rumi, hated by many, he was labeled an intoxicated Sufi and is still read today. After his arrest in Sūs and a lengthy period of confinement (c. 911–922) in Baghdad, al-Ḥallāj was eventually crucified and brutally tortured to death. A large crowd witnessed his execution. He is remembered to have endured gruesome torture calmly and courageously and to have uttered words of forgiveness for his accusers. In a sense, the Islāmic community (ummah) had put itself on trial, for al-Ḥallāj left behind revered writings and supporters who courageously affirmed his teachings and his experience. In subsequent Islāmic history, therefore, the life and thought of al-Ḥallāj has been a subject seldom ignored. Here we get a realistic overview about him and his teachings.

Fabrication and Characterization of Carbon Based Nanostructures

The increased level of industrial pollutants in water and drug resistant pathogens are serious threat to human and aquatic life. Graphene based materials are an attractive choice due to numerous fascinating features of graphene. However, combining graphene with other nanomaterials in the form of nanocomposites give a window of opportunities to fabricate and investigate new materials. Herein, a set of four graphene based nanocomposites are presented that are combination of graphene and metal/non-metal oxides. These nanocomposites are synthesized, systematically characterized and are compared for their performance in environmental and biomedical applications. As a start-up, synthesis, the physio-chemical characterizations, photocatalytic and antibacterial properties of MgO and graphene nanoplatelets (GNPs) nanocomposites are presented. The crystallinity, phase, morphology, chemical bonding, and vibrational modes of prepared nanomaterials are studied. The conducting nature of GNPs is tailored via photocatalysis and enhanced antibacterial activity. It is interestingly observed that the MgO/GNPs nanocomposite with optimized GNPs content shows a significant photocatalytic activity (97.23% degradation) as compared to bare MgO (43%) which makes it the potential photocatalyst for purification of industrial waste water. In addition, the effect of increased quantity of GNPs on antibacterial performance of nanocomposites against pathogenic microorganisms is researched, suggesting them toxic. MgO/GNPs 25% nanocomposite may have potential applications in waste water treatment and nanomedicine due its multifunctionality. In the following chapter, immobilization of monodispersed silicon dioxide (SiO2) nanoparticles on multiple graphene layers is demonstrated for intercalation of graphene nanoplatelets. The exceptional conducting nature of graphene makes it a viable candidate for enhancing the effectiveness of photocatalytic and biomedical nanomaterials. Interestingly, the addition of graphene nanoplatelets with SiO2 nanoparticles enhances the photocatalytic efficiency from 46% to 99%. For biomedical applications, it is found that 75% of Gram positive and 50% of Gram negative bacteria have been killed; hence, bacterial proliferation is significantly restricted. The prepared nanocomposites with a controlled amount of carbon in the form of graphene can be employed for photocatalysis based waste water remediation and biomedicine. However, the photocatalytic and antibacterial performance obtained up to this stage of work is moderate only. An effective, fast and economic dye removal method is essential to meet the stringent economic requirements. Therefore, graphene/Fe3O4 nanocomposite is chosen. This nanocomposite obtained via soft chemical method is characterized for its crystallinity, morphology, microstructure, vibrational modes and magnetic properties. Graphene sheets decorated with magnetite nanoparticles are investigated for their photocatalytic response against methyl orange. The study reveals that the conducting nature of graphene, engineered bandgap and photo Fenton like reaction synergistically govern the efficient photocatalytic activity of nanocomposite. Interestingly, it is observed that methyl orange can be completely removed i.e., upto 99.24% by graphene/Fe3O4 nanocomposite (Fz) in 30 min only, whereas the removal efficiency is 43% for Fe3O4 nanoparticles, alone. The presence of graphene endows the delay in charge carriers’ recombination whereas, photo Fenton like reaction stimulates the generation of reactive oxygen species. This ultimately leads to the highly enhanced photocatalytic activity and complete removal of methyl orange. The magnetically separable photocatalyst, presented in this work, offers great prospects for fast and economical decontamination of dye polluted water. The antibacterial performance is also significantly enhanced but a complete pathogen control is not achieved. At final stage, NiO nanoflakes and graphene/NiO nanocomposite are synthesized. A study on their crystal phase analysis and morphology is presented. In addition, HRTEM images, SAED patterns and Raman modes are also investigated. A solar light induced dye removal and bactericidal properties of nickel oxide (NiO) and GNPs nanocomposites are presented. The conducting nature of GNPs is the key factor that governs the enhanced photocatalytic and antibacterial activity. It is interestingly found that the graphene/NiO nanocomposite shows outstanding photocatalytic activity (99% degradation) as compared to NiO (34%) alone, which makes it potential candidate for depollution of dye contaminated water. 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