WAVELET AND SINE BASED ANALYSIS OF PRINT QUALITY EVALUATIONS

Recent advances in imaging technology have resulted in a proliferation of images across different media. Before it reaches the end user, these signals undergo several transformations, which may introduce defects/artifacts that affect the perceived image quality. In order to design and evaluate these imaging systems, perceived image quality must be measured. This work focuses on analysis of print image defects and characterization of printer artifacts such as banding and graininess by using a human visual system (HVS) based framework. Specifically the work addresses the prediction of visibility of print defects (banding and graininess) by representing the print defects in terms of the orthogonal wavelet and sinusoidal basis functions and combining the detection probabilities of each basis functions to predict the response of the human visual system (HVS). The detection probabilities for basis function components and the simulated print defects are obtained from separate subjective tests. The prediction performance from both the wavelet based and sine based approaches is compared with the subjective testing results .The wavelet based prediction performs better than the sinusoidal based approach and can be a useful technique in developing measures and methods for print quality evaluations based on HVS

Recent Progress in the Development of INCITS W1.1, Appearance-Based Image Quality Standards for Printers

In September 2000, INCITS W1 (the U.S. representative of ISO/IEC JTC1/SC28, the standardization committee for office equipment) was chartered to develop an appearance-based image quality standard.(J),(2) The resulting W1.1 project is based on a proposal(4) that perceived image quality can be described by a small set of broad-based attributes. There are currently five ad hoc teams, each working towards the development of standards for evaluation of perceptual image quality of color printers for one or more of these image quality attributes. This paper summarizes the work in progress

Investigations into Convective Deposition from Fundamental and Application-Driven Perspectives

Crystalline particle coatings can provide critical enhancement to wide-ranging energy and biomedical device applications. One method by which ordered particle arrays can be assembled is convective deposition. In convective deposition, particles flow to a surface via evaporation-driven convection, then order through capillary interactions. This thesis will serve to investigate convective deposition from fundamental and application-driven perspectives. Motivations for this work include the development of point-of-care diagnostic devices, macroporous membranes, and various energy applications. Immunoaffinity cell capture devices display enhanced diagnostic capabilities with intelligently varied surface roughness in the form of particle coatings. Relatedly, highly crystalline particle coatings can be used to template the fabrication of macroporous polymer membranes. These membranes display highly monodisperse pores at particle contact points. In addition, ordered areas of particles, acting as microlenses, can enhance LED performance by 2.66-fold and DSSC efficiency by 30%. Previous research has targeted the formation of crystalline monolayers of particles. However, much insight can be gleaned from imperfect coatings. The analysis of submonolayer coatings, exhibiting significant void spaces, provides insight as to the specific mechanisms and timescales for flow and crystallization. A pair of competing deposition modes, termed ballistic and locally-ordered, enables the intelligent design of experiments and enables significant enhancement in control of resultant thin film morphology. Surface tension-driven particle assembly is subject to a number of native instabilities and macroscale defects that can irreversibly compromise coating uniformity. These include the formation of three-dimensional streaks, where surface tension-driven flow spurs on the nucleation of large imperfections. These imperfections, once nucleated, exhibit a feedback loop of dramatically enhanced evaporation and resultant flow. In addition, thick nanoparticle coatings, subject to enormous drying stresses, exhibit highly uniform crack formation and spacing in an attempt to minimize system energy. Both these imperfections yield insight on convective deposition as a fundamental phenomenon, and intelligent design of experiments moving forward. Cracking can be suppressed through layer-by-layer particle assembly, whereas streaking can be controlled via several significant process enhancements. Process enhancements include the addition of smaller constituent, as packing aids, to suspension, the application of lateral vibration, and the reversal of relevant surface tension gradients. The transition from unary to binary suspensions represents a significant improvement to convective deposition as a process. Nanoparticles act as packing, and flow, aids, wholly suppress macroscale defects under ideal conditions. A relative deficiency or excess of nanoparticles can generate complex coating morphologies including multilayers and transverse stripes. The application of lateral vibration to convective deposition allows the assembly of monolayer particle coatings under a larger range of operating conditions and at a faster rate. Macroscale defect formation can increased through an enhancement of the natural condition, where evaporative cooling generates a thermal gradient in drying droplets. Conversely, these defects can be suppressed with a reversal of this gradient, which will reverse the direction of surface tension-driven recirculation. These fundamental developments in understanding, and associated process enhancements, are critical in current efforts to scale up convective deposition. As convective deposition evolves from laboratory-scale batch experiments to continuous, large scale, coatings, repeatability and robustness, as well as an ability to controllably change thin film morphology, will be essential

SYMLET AND GABOR WAVELET PREDICTION OF PRINT DEFECTS

Recent studies have been done to create models that predict the response of the human visual system (HVS) based on how the HVS processes an image. The most widely known of these models is the Gabor model, since the Gabor patterns closely resemble the receptive filters in the human eye. The work of this thesis examines the use of Symlets to represent the HVS, since Symlets provide the benefit of orthogonality. One major problem with Symlets is that the energy is not stable in respective Symlet channels when the image patterns are translated spatially. This thesis addresses this problem by up sampling Symlets instead of down sampling, and thus creating shift invariant Symlets. This thesis then compares the representation of Gabor versus Symlet approach in predicting the response of the HVS to detecting print defect patterns such as banding and graining. In summary we noticed that Symlet prediction outperforms the Gabor prediction thus Symlets would be a good choice for HVS response prediction. We also concluded that for banding defect periodicity and size are important factors that affect the response of the HVS to the patterns. For graining defects we noticed that size does not greatly affect the response of the HVS to the defect patterns. We introduced our results using two set of performance metrics, the mean and median

Tent-pole spatial defect pooling for prediction of subjective quality assessment of streaks and bands in color printing

Abstract. An algorithm is described for measuring the subjective, visual impact of 1-D defects (streaks and bands

Experimental Characterization and Synthesis of Nanotwinned Ni-Mo-W Alloys

Microelectromechanical systems (MEMS) have transformed consumer and industrial products through the integration of mechanical and electrical components within a single package. MEMS are ubiquitous in society, found predominantly in consumer electronics and automotive industries, providing interconnectivity across a wide variety of devices and everyday objects. To date, the materials selection for the structural element of many MEMS devices has been limited to a relatively small subset of materials, with silicon being the dominant choice. Employing MEMS sensors and switches in extreme environments will need advanced materials with a synergistic balance of properties, e.g. high strength, density, electrical conductivity, dimensional stability, and microscale manufacturability, but MEMS materials with this suite of properties are not readily available. Metallic systems are especially attractive for these applications due to their high density, strength and electrical conductivity. For this reason, metal MEMS materials are the motivation and focus for this dissertation. The synthesis of nanotwinned nickel-molybdenum-tungsten (Ni-Mo-W) alloys resulted in thin films with a very favorable suite of properties. Combinatorial techniques were employed to deposit a compositional spread of Ni85MoxW15-x, alloys and to investigate their physical and mechanical properties as a function of alloy chemistry. The addition of Mo and W was shown to significantly decrease the coefficient of thermal expansion (CTE) and provide a route for tailoring the CTE and its temperature dependence with compositional control. The measured CTE values for Ni-Mo-W matched that of commercial glass substrates currently employed in MEMS devices, broadening the spectrum of materials with the requisite dimensional stability for use in layered structures. Microscale mechanical testing was used to measure the in-plane tensile properties; a linear-elastic response with fracture strengths ranging from 2-3 GPa was uncovered. The ultrahigh tensile strengths are attributed to the presence of highly-aligned nanotwins and their effectiveness as obstacles to dislocation motion. In situ micropillar experiments demonstrated compressive strengths of 3-4 GPa and extremely localized plasticity, both of which are strongly orientation dependent. The nanoscale twins underpinning this mechanical behavior do not impede motion of electrons, and nanotwinned Ni-Mo-W thin films were found to posses the electrical conductivity of bulk Ni alloys. Taken as a whole, this study highlights the balance of physical, thermal and mechanical properties for Ni-Mo-W, driven by nanoscale twin formation. Deposition of Ni-Mo-W films displayed a wide processing window for the formation of the requisite nanotwinned microstructure and attendant properties (CTE, strength, ductility and electrical resistivity). Microcantilever beams were designed and fabricated using traditional integrated circuit processing to translate thin film properties into prototype MEMS device structures. Laser interferometry was used to certify the dimensional stability of the cantilever beams as-fabricated and after thermal exposure at elevated temperatures associated with wafer bonding. Micromachined cantilever beams showed excellent dimensional stability with beam deflection profiles on the order of tens of nanometers, elucidating a path beyond outstanding material properties to actual device structures for next generation metal MEMS devices

Multiscale characterization of ferroelastic deformation in ceramic materials

Ceramic materials offer a variety of useful properties that make them desirable for a wide range of engineering applications, however, ceramics are limited in their utility by low toughness. Ferroelastic deformation provides a mechanism through which ceramics are intrinsically toughened, but the effect of microstructure on the deformation behavior has yet to be fully understood. In this present examination, the behavior of ferroelastic deformation was evaluated on a range of length scales, specifically highlighting the influence of several variables on the domain nucleation behavior. Ferroelastic domain nucleation was first evaluated in micro-scale single crystals. The stress required for domain nucleation was measured while crystal orientation was tracked. Domain nucleation was observed to not follow a critical resolved shear stress criterion, suggesting that orientation alone cannot be used to predict the deformation behavior. Furthermore, multiple types of deformation were observed to act in concert with ferroelastic deformation. This suggests that domain nucleation is a complex process that may involve multiple potential mechanisms of deformation. Domain nucleation in bulk polycrystals was also examined. Statistics collected on grain sizes that more frequently contain mechanically nucleated domains show that larger grains in close proximity to finer grains more frequently deform. The deformation behavior in polycrystals was contrasted against the domain nucleation behavior in single crystal nanopillars. The nanopillars exhibited high deformation stress, while prolific domain nucleation without fracture was observed in polycrystals. These results suggest that local constraints imposed by microstructure play a key role in locally increasing shear stresses responsible for domain nucleation. To design microstructures with specific characteristics, ceramic processing routes must also be developed to control microstructural development during fabrication. To this end, spark plasma sintering (SPS) offers a promising processing route for fabricating dense nanostructured ceramics. The densification mechanisms associated with ceramic processing using SPS have also been investigated in the present work. Results collected on many samples that were processed under identical processing control conditions convey significant variability in the resulting material properties between and within individually produced samples. Furthermore, the results indicate that electric current plays an important role in densifying ionic conducting ceramics during sintering using SPS. Overall, the research presented in this dissertation shows that ferroelastic domain nucleation is a complex process involving several competing and cooperating mechanisms, and that domain nucleation is affected by different microstructural variables. Domain nucleation cannot be predicted based solely on crystal orientation, however, other microstructural variables including grain size do significantly impact the ferroelastic deformation behavior. Microstructures with large ferroelastic grains embedded in a more finely grained matrix promote ferroelastic deformation even without fracture, and the deformation is sensitive to the stress state being applied. Several processing routes presented here result in these favorable bimodal grain size distributions and may be tested more thoroughly in the future to explore the effect that such microstructures have on the intrinsic toughness

Test Targets 6.0: A Collaborative effort exploring the use of scientific methods for color imaging and process control

Test Targets is a collection of scholarly papers contributed by faculty, students, and alumni of Rochester Institute of Technology. We realize the importance of having faculty set examples as authors for students to follow. We have a three-course sequence over a time span of a year to prepare students to publish their first articles when completing Tone and Color Analysis, Printing Process Control, and Advanced Color Management. In this instance, Test Targets 6.0 is a part of the course content in the Advanced Color Management course