50. Measuring image artifacts - moire artifacts - 2011

50. Measuring image artifacts - moire artifacts - 2011 -...

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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 in Banding and MTF Characterization Moiré Artifact Prediction and Reduction in a Variable Data Printing Environment Conclusions References
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HP-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 artifacts
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HP-PURDUE-CONFIDENTIAL Final Exam May 16th 2008 Slide No. 3 Quality of Embedded Images Example: Moiré Artifact Business Week, April 30, 2007 p.56
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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 image
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HP-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 device
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HP-PURDUE-CONFIDENTIAL Final Exam May 16th 2008 Slide No. 6 Phases and Components of Automatic Workflow [3]
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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
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HP-PURDUE-CONFIDENTIAL Final Exam May 16th 2008 Slide No. 8 Illustration of Halftone Spectrum for a Sine Wave Image Continuous-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
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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 C A’ B’ C’
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HP-PURDUE-CONFIDENTIAL Final Exam May 16th 2008 Slide No. 10
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50. Measuring image artifacts - moire artifacts - 2011 -...

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