AN INTRODUCTION MATERIALS - DTIC
pitch with a rotation between are superimposed, the moire fringe pattern shown in Figure 3 is obtained Generally, a deformed grating is a combination of elongation and rotation result-ing in moire fringes that represent lines of equal displacement, as shown in Figure 4
50 Measuring image artifacts - moire artifacts - 2011
Image scaling and rotation center of the test page Measuring image artifacts - moire artifacts - 2011 ppt Author:
The perception of movement and depth in moire patterns
Moire patterns can produce striking movement effects and in more complex stimuli page 178 ] Similar phenomena have been reported for other stimuli Note also that any rotation of the foil
04-Basic Interferometry and Optical Testing
Aug 04, 2016 · Page 2 4 0 Basic Interferometry and Optical Testing 4 1 Two-Beam Interference 4 2 Pioneer Fizeau Interferometer 4 3 Twyman-Green Interferometer 4 4 Fizeau Interferometer - Laser-Source 4 5 Mach-Zehnder Interferometer 4 6 Typical Interferograms 4 7 Interferograms and Moiré Patterns
OpenStax University Physics Volume I Unit 1: Mechanics
Chapter 10: Fixed-Axis Rotation Page 5 of 34 a ω=25 0(2 0s) = 50 0rad s; b 25 0 rad/s 2 d dt ω α= = 36 The angular position of a rod varies as 20 0 t 2 radians from time t =0 The rod has two beads on it as shown in the following figure, one at 10 cm from the rotation axis and the other at 20 cm from the rotation axis
The specific rotation of sugar (sucrose)
The specific rotation of sugar (sucrose) When plane-polarized light is passed through an enantiomerically pure solution of chiral molecules1 or a solution where there is an excess of one enantiomer as compared to the
Measurement of Thermal Deformation of BGA Using Phase
Plot without Rotation, (c) Surface Plot with Three-Corner Rotation and (d) Surface Plot with Best-Fit-Plane Rotation Measurement of BGA and PWB Interconnect Area Using Phase-Stepping Fig 5 shows the experimental set-up that is used for the measurement of the thermal deformation of BGAs and printed circuit boards The system, commercially
Torque Torque and Rotational Inertia
connected to the axis of rotation by a massless rod with length r, I = mr 2 If the mass is distributed at different distances from the rotation axis, the moment of inertia can be hard to calculate The expressions for I for several standard shapes are listed on the next page m Axis of r rotation 12 3 2 A table of rotational inertia
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HP-PURDUE-CONFIDENTIAL Final Exam May 16th 2008
Slide No. 1
Outline
Motivations Analytical Model of Skew Effect and its Compensation inBanding and MTF Characterization
Moiré Artifact Prediction and Reduction in a Variable DataPrinting Environment
Conclusions ReferencesHP-PURDUE-CONFIDENTIAL Final Exam May 16th 2008
Slide No. 2
Moiré Artifacts in Printing
Moiré due to halftoning process Test pattern used to characterize halftoning processing of press Example image to be printed showing moiré artifactsHP-PURDUE-CONFIDENTIAL Final Exam May 16th 2008
Slide No. 3
Quality of Embedded Images Example: Moiré ArtifactBusiness Week, April 30, 2007 p.56
HP-PURDUE-CONFIDENTIAL Final Exam May 16th 2008
Slide No. 4
Document Composition Affects Artifact Perceptibility Artifact assessment depend on document composition: Image scaling and rotation Image cropping Image position relative to other objects Background color Object overlay on imageHP-PURDUE-CONFIDENTIAL Final Exam May 16th 2008
Slide No. 5
Causes and Difficulties to Detect Moiré Artifacts in VDP Halftone screen pattern interacts with digital image Clustered dot profile Limited spatial resolution of the digital press Typical digital press : 180 line-per-inch In digital publishing environment with variable data printing Inspecting each printed page is not cost efficient Moiré artifacts are image content dependent Moiré artifacts vary with the printing deviceHP-PURDUE-CONFIDENTIAL Final Exam May 16th 2008
Slide No. 6
Phases and Components of Automatic Workflow
[3]HP-PURDUE-CONFIDENTIAL Final Exam May 16th 2008
Slide No. 7
Spectrum of Halftoned Digital Image in Terms of Spectrum of Original Continuous-tone Image Spectrum of the halftoned digital image can be expressed in terms of the original image and the halftone screen
H(u,v) -- spectrum of halftone image f[l,k] -- original image p[m,n;a] -- halftone dot profile M - size of the halftone cell
HP-PURDUE-CONFIDENTIAL Final Exam May 16th 2008
Slide No. 8
Illustration of Halftone Spectrum for a Sine Wave ImageContinuous-tone input image Halftone image
Screening
Compare
5 1 6 12 4 0 2 10 8 3 7 13 14 9 11 15
Threshold matrix Spectrum of the continuous-tone input image Spectrum of the halftone image Frequency doubling effect Frequency of the original sinusoidal wave
HP-PURDUE-CONFIDENTIAL Final Exam May 16th 2008
Slide No. 9
Nonlinear Transformation Due to Halftone
|P[0,0;a]| |P[0,1;a]| |P[0,2;a]| |P[1;a]| f[l] a l l P[1;f[l]] 1 T T 0 A B CA' B' C'
HP-PURDUE-CONFIDENTIAL Final Exam May 16th 2008
Slide No. 10
Frequency Doubling Effect Due to Nonlinear Transformation The frequency doubling effect is due to the non-linear transform caused by the screening process
Clustered halftone dot profile that is used in laser printing is likely to cause this frequency doubling effectHP-PURDUE-CONFIDENTIAL Final Exam May 16th 2008
Slide No. 11
Moiré Artifact as Result of Frequency Doubling EffectContinuous-tone input image Halftone image
Screening
Compare
5 1 6 12 4 0 2 10 8 3 7 13 14 9 11 15
Threshold matrix Spectrum of the continuous-tone input image Spectrum of the halftone image Moiré artifacts as low frequency component Frequency of the original sinusoidal wave
HP-PURDUE-CONFIDENTIAL Final Exam May 16th 2008
Slide No. 12
Moiré Prediction
Image Database Press Profile Detection Algorithm Human Visual System ModelMoiré Map
Image Analysis Test Pattern Digital Press Real-time analysis of images in document Offline press characterization process
HP-PURDUE-CONFIDENTIAL Final Exam May 16th 2008
Slide No. 13
Digital Press Characterization
Use Bullseye test pattern Sweep of signal at all angles Spatial frequency at each location is proportional to its distance to the center Bullseye test pattern is printed using target digital press Moiré inducing frequency (MIF) generates low frequency moiré that forms secondary bullseye pattern on the print After scanning the printout, we detect the secondary bullseye pattern to locate MIF Halftone bullseye test pattern with moiré artifactsHP-PURDUE-CONFIDENTIAL Final Exam May 16th 2008
Slide No. 14
Moiré Inducing Frequency (MIF) Detection on Test Page This test pattern shows multiple moiré artifacts patterns Each moiré artifact exhibits a pattern of concentric circles The xy coordinates of the centerof each pattern of concentric circles correspond to a frequency that may cause moiré artifacts in the printed image
moiré artifactsHP-PURDUE-CONFIDENTIAL Final Exam May 16th 2008
Slide No. 15
Bullseye pattern halftoned with 150 cycles/inch, 0 degree screen; printed at 600 dpi and scanned at 600 dpi. The red dots indicate detected MIF's
Symmetry of the Secondary Bullseye Artifacts
The secondary bullseye artifacts are symmetric to the center of the test page Each secondary bullseye artifact forms concentric circles Some pairs of secondary bullseye artifacts that are symmetrical to the center show different gray levelsHP-PURDUE-CONFIDENTIAL Final Exam May 16th 2008
Slide No. 16
1-D illustration
Image: 5 cycles per inch Screen: 10 cycles per inch Average: 0.375 Average: 0.4667 Same frequencyHP-PURDUE-CONFIDENTIAL Final Exam May 16th 2008
Slide No. 17
Anisotropy Measurements on Scanned Bullseye Pattern [4] Each image pixel's anisotropy measurement is calculated based on a disk area Image pixels within the disk is divided into annuli The width of each annulus is delta, ∆ Image pixels are sorted into annulus (bins) based on their distance to the center of the region Mean and variance are calculated for each bin Calculate Anisotropy for each binHP-PURDUE-CONFIDENTIAL Final Exam May 16th 2008
Slide No. 18
Modified Anisotropy Measurement Secondary Bullseye Artifacts Modified anisotropy measurement takes account on the entire region's energy to give better distinction between concentric circles (secondary bullseye) and random noise region
HP-PURDUE-CONFIDENTIAL Final Exam May 16th 2008
Slide No. 19
Bullseye pattern halftoned with 150 lines/inch, 0 degree screen; printed at 600 dpi and scanned at 600 dpi. The red dots indicate detected MIF's
Printer MIF Detection Result
Maximal frequency: 90 cycles/inch Maximal frequency: 55 cycles/inchHP-PURDUE-CONFIDENTIAL Final Exam May 16th 2008
Slide No. 20
MIF Detection on Test Page
Radial Frequency
(cycles per inch) Angle (degrees)37 ±90 50 ±90 75 ±90 57 ±64 67 ±64 75 ±64 50 ±45 72 ±45 75 ±45 57 ±26 67 ±26 75 ±26 37 0 45 0 75 0
HP-PURDUE-CONFIDENTIAL Final Exam May 16th 2008
Slide No. 21
MIF detection in the continuous-tone input image
Based on press profile, measure the energy of MIF in power spectrum of the digital image Find peaks in the spectrum of the continuous-tone image that corresponding to MIF frequency In frequency domain, calculate a confidence measure in the neighborhood of the peaks Calculate the size of each detected region to eliminate false alarms due to strong edge componentsHP-PURDUE-CONFIDENTIAL Final Exam May 16th 2008
Slide No. 22
MIF Detection on Digital Images
Sampling frequency of the digital image on print-out: Image Metadata in PPML or XML Dimension: image width/height size Position: Determined by the attribute "Position" in MARK and
OBJECT elements
Transform Matrix: provides various image properties such as scale, skew, and translation Clipping size: determined by the attribute "Rectangle" in CLIP_RECT elementHP-PURDUE-CONFIDENTIAL Final Exam May 16th 2008
Slide No. 23
Indices Representing MIF in Frequency Domain
Check for MIF on the 2D-DSFT of the digital image:HP-PURDUE-CONFIDENTIAL Final Exam May 16th 2008
Slide No. 24
Confidence Measurement in Frequency Domain
In frequency domain, calculate a confidence measure in the neighborhood of the peaksPower spectrum
HP-PURDUE-CONFIDENTIAL Final Exam May 16th 2008
Slide No. 25
Confidence Measure
Strong peak in power spectrum at the MIF location means perceptible moiré is likely to occur in printing
Confidence measure helps to reduce misclassificationPower Spectrum
HP-PURDUE-CONFIDENTIAL Final Exam May 16th 2008
Slide No. 26
Results: Sinusoidal Grating
Digitally generated sinusoidal grating Starting from 10 cycles/inch with 20 cycles/inch increment per row Starting from 0 degree with 10 degrees increment per column Detection is done for 90 cycles/inch with 10 degreesHP-PURDUE-CONFIDENTIAL Final Exam May 16th 2008
Slide No. 27
Misclassification Due to Strong Edges
HP-PURDUE-CONFIDENTIAL Final Exam May 16th 2008
Slide No. 28
Measure Length and Width of Each Detected Region
Project each region to the horizontal and vertical axis of the image plan Count the number of pixels on each horizontal and vertical position Regions with maximal length or width less than 2N (N: the 2D DSFT window size) will be removed from mask. Projection to obtain width region identified in moiré maskHP-PURDUE-CONFIDENTIAL Final Exam May 16th 2008
Slide No. 29
Misclassification Regions Removed
HP-PURDUE-CONFIDENTIAL Final Exam May 16th 2008
Slide No. 30
Adaptive Scaling to Reduce Moiré
For each image identified with moiré we scaled the image to reduce moiré artifacts in print-out
Each region on the moiré mask is analyzed to obtain a scale factor Global scale factor is the maximal of all the regional scale factors Entire image is scaled by the global factor
HP-PURDUE-CONFIDENTIAL Final Exam May 16th 2008
Slide No. 31
Results: Shirt
Printed using HP LaserJet 5500 with 600 dpi and 150 lpi halftone Visible moiré artifacts on the shirt region Successful detection of using the printer profileHP-PURDUE-CONFIDENTIAL Final Exam May 16th 2008
Slide No. 32
Results: Hotel
Original digital image Moiré mask Scan of the original image print-out Scan of the scaled image print-out
HP-PURDUE-CONFIDENTIAL Final Exam May 16th 2008
Slide No. 33
Results: Kodak Window
Original digital image Moiré mask Scan of the original image print-out Scan of the scaled image print-out
HP-PURDUE-CONFIDENTIAL Final Exam May 16th 2008
Slide No. 34
Summary
Analyze the relationship between the spectrum of halftone image and that of the original image
Use bullseye pattern to characterize printer Identified moiré inducing frequency Predict moiré artifacts based on the image content, image
pixel size, and actual printed size Adaptive image scaling to resize the image so that the new image will not induce moiré artifactsquotesdbs_dbs15.pdfusesText_21