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Papers by Robert Loce
Journal of Electronic Imaging, 2011
Moiré in color printing is an undesirable visible artifact that can arise from overlaying multipl... more Moiré in color printing is an undesirable visible artifact that can arise from overlaying multiple halftone color separations. Halftone geometric configurations designed to avoid moiré in the overlays strictly require that individual halftone color separations must possess a low degree of relative distortion. However, optical and mechanical errors of multiple imaging systems within a printer usually produce differences between the
Journal of imaging technology, 1990
An imaging model has been developed to investigate halftone banding due to photoconductor vibrati... more An imaging model has been developed to investigate halftone banding due to photoconductor vibrations. Nonuniform, vibratory motion of the photoconductor in an image bar printer leads to exposure modulation in halftoned areas on the photoconductor and reflectance modulation on the print. The exposure modulation at the spatial frequency of the vibration is proportional to the fractional velocity error, but is relatively independent of system parameters for typical cases. A xerographic system model has been coupled to the imaging model to calculate the print reflectance modulation (banding) due to vibrations
Misregistration between the color separations of a printed image, which is often inevitable, can ... more Misregistration between the color separations of a printed image, which is often inevitable, can cause objectionable color shifts in average color. We analyze the impact of inter-separation misregistration on clustered-dot halftones using Fourier analysis in a lattice framework. Our analysis provides a complete characterization of the conditions under which the average color is invariant to displacement misregistration. In addition to known conditions on colorant spectra and periodicity of the halftones, the work reveals that invariance can also be obtained when these conditions are violated for suitable dot shapes and displacements. Examples for these conditions are included, as is the consideration of traditional halftone configurations.
Optical Engineering
The hit-or-miss operator is used as the building block of optimal binary restoration filters. Fil... more The hit-or-miss operator is used as the building block of optimal binary restoration filters. Filter design methodologies are given for general-, maximum-, and minimum-noise environments, the latter two producing optimal thinning and thickening filters, respectively, ...
Typical office scanners employ a moving linear-sensor array or moving optics. The velocity of the... more Typical office scanners employ a moving linear-sensor array or moving optics. The velocity of the components is generally not constant in time. It may be modulated directly (at one or more frequencies) by dynamic errors of gears, timing belts, and motors, and indirectly by structural vibrations induced by gears, fans, etc. Nonuniform velocity is known to cause undesirable brightness fluctuation
Images scanned in the presence of mechanical vibrations are subject to artifacts such as brightne... more Images scanned in the presence of mechanical vibrations are subject to artifacts such as brightness fluctuation and geometric warping. The goal of this work is to develop an algorithm to invert these distortions and produce an output digital image consistent with a scanner operating under ideal uniform motion conditions. The image restoration algorithm described in this paper applies to typical
Storage and Retrieval for Image and Video Databases, 1997
Page 1. hit Enhancement and Restoration of Digital Documents Statistical Design of Nonlinear Algo... more Page 1. hit Enhancement and Restoration of Digital Documents Statistical Design of Nonlinear Algorithms Robert P. Loce Edward R. Dougherty Page 2. Page 3. Page 4. Page 5. Enhancement and Restoration of Digital Documents Statistical Design of Nonlinear Algorithms Page ...
Page 1. hit Enhancement and Restoration of Digital Documents Statistical Design of Nonlinear Algo... more Page 1. hit Enhancement and Restoration of Digital Documents Statistical Design of Nonlinear Algorithms Robert P. Loce Edward R. Dougherty Page 2. Page 3. Page 4. Page 5. Enhancement and Restoration of Digital Documents Statistical Design of Nonlinear Algorithms Page ...
Journal of Electronic Imaging, 2011
Moiré in color printing is an undesirable visible artifact that can arise from overlaying multipl... more Moiré in color printing is an undesirable visible artifact that can arise from overlaying multiple halftone color separations. Halftone geometric configurations designed to avoid moiré in the overlays strictly require that individual halftone color separations must possess a low degree of relative distortion. However, optical and mechanical errors of multiple imaging systems within a printer usually produce differences between the
Journal of imaging technology, 1990
An imaging model has been developed to investigate halftone banding due to photoconductor vibrati... more An imaging model has been developed to investigate halftone banding due to photoconductor vibrations. Nonuniform, vibratory motion of the photoconductor in an image bar printer leads to exposure modulation in halftoned areas on the photoconductor and reflectance modulation on the print. The exposure modulation at the spatial frequency of the vibration is proportional to the fractional velocity error, but is relatively independent of system parameters for typical cases. A xerographic system model has been coupled to the imaging model to calculate the print reflectance modulation (banding) due to vibrations
Misregistration between the color separations of a printed image, which is often inevitable, can ... more Misregistration between the color separations of a printed image, which is often inevitable, can cause objectionable color shifts in average color. We analyze the impact of inter-separation misregistration on clustered-dot halftones using Fourier analysis in a lattice framework. Our analysis provides a complete characterization of the conditions under which the average color is invariant to displacement misregistration. In addition to known conditions on colorant spectra and periodicity of the halftones, the work reveals that invariance can also be obtained when these conditions are violated for suitable dot shapes and displacements. Examples for these conditions are included, as is the consideration of traditional halftone configurations.
Optical Engineering
The hit-or-miss operator is used as the building block of optimal binary restoration filters. Fil... more The hit-or-miss operator is used as the building block of optimal binary restoration filters. Filter design methodologies are given for general-, maximum-, and minimum-noise environments, the latter two producing optimal thinning and thickening filters, respectively, ...
Typical office scanners employ a moving linear-sensor array or moving optics. The velocity of the... more Typical office scanners employ a moving linear-sensor array or moving optics. The velocity of the components is generally not constant in time. It may be modulated directly (at one or more frequencies) by dynamic errors of gears, timing belts, and motors, and indirectly by structural vibrations induced by gears, fans, etc. Nonuniform velocity is known to cause undesirable brightness fluctuation
Images scanned in the presence of mechanical vibrations are subject to artifacts such as brightne... more Images scanned in the presence of mechanical vibrations are subject to artifacts such as brightness fluctuation and geometric warping. The goal of this work is to develop an algorithm to invert these distortions and produce an output digital image consistent with a scanner operating under ideal uniform motion conditions. The image restoration algorithm described in this paper applies to typical
Storage and Retrieval for Image and Video Databases, 1997
Page 1. hit Enhancement and Restoration of Digital Documents Statistical Design of Nonlinear Algo... more Page 1. hit Enhancement and Restoration of Digital Documents Statistical Design of Nonlinear Algorithms Robert P. Loce Edward R. Dougherty Page 2. Page 3. Page 4. Page 5. Enhancement and Restoration of Digital Documents Statistical Design of Nonlinear Algorithms Page ...
Page 1. hit Enhancement and Restoration of Digital Documents Statistical Design of Nonlinear Algo... more Page 1. hit Enhancement and Restoration of Digital Documents Statistical Design of Nonlinear Algorithms Robert P. Loce Edward R. Dougherty Page 2. Page 3. Page 4. Page 5. Enhancement and Restoration of Digital Documents Statistical Design of Nonlinear Algorithms Page ...