22. Halftoning_fundamentals - 2011

22. Halftoning_fundamentals - 2011 - 1 Halftoning...

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Advanced Digital Halftoning – 2 October 2011 1.1 1. Halftoning Fundamentals
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Advanced Digital Halftoning – 2 October 2011 1.2 Outline Goals of halftoning Taxonomy of halftoning textures Architectures for halftoning algorithms Training-based approaches to algorithm design Impact of printer and viewer Halftone quality metrics
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Advanced Digital Halftoning – 2 October 2011 1.3 1.1 What is digital halftoning? Digital halftoning is the process of rendering a continuous- tone image with a device that is capable of generating only two or a few levels of gray at each point on the device output surface. The perception of additional levels of gray depends on a local average of the binary or multilevel texture.
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Advanced Digital Halftoning – 2 October 2011 1.4 What is digital halftoning (cont.) Detail is rendered by local modulation of the texture
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Advanced Digital Halftoning – 2 October 2011 1.5 History Fundamental concepts have been used for centuries in weaving and engraving
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Advanced Digital Halftoning – 2 October 2011 1.6 History (cont.) Photomechanical halftoning process was introduced by Talbot in 1852.
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Advanced Digital Halftoning – 2 October 2011 1.7 History (cont.) Digital halftoning algorithms first appeared in the early 70s as computer graphics displays and hardcopy devices became more widely available. Bayer - 1972 Floyd-Steinberg - 1976
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Advanced Digital Halftoning – 2 October 2011 1.8 Overview of Imaging Pipeline Page description language (PDL) to print Interpret page description language Render objects on display list scale crop rotate Display List 24 bit RGB raster image Color conversion color space conversion gamut mapping appearance matching undercolor removal trapping Compress Decompress Store 32 bit CMYK raster image Halftone 4 bit CMYK raster image Marking Engine 24 bit RGB raster image Color conversion 24 bit RGB raster image
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Advanced Digital Halftoning – 2 October 2011 1.9 Overview of Printing Technologies Two dominant technologies – Electrophotographic (EP) process – Inkjet (IJ) Traditionally: – EP has been used in faster, higher capacity, higher cost business platforms. – IJ has been used in slower, lower capacity, lower cost home/small business platforms. But the boundary is blurring somewhat: – Very low cost EP printers are now available. – IJ speed and performance continues to improve.
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Advanced Digital Halftoning – 2 October 2011 1.10 Overview of Printing Technologies Laser scan mechanism for electrophotographic printer
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Advanced Digital Halftoning – 2 October 2011 1.11 Overview of Printing Technologies Electrophotographic imaging process
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Advanced Digital Halftoning – 2 October 2011 1.12 Overview of Printing Technologies InkJet print mechanism Photos courtesy Hewlett-Packard Co.
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Advanced Digital Halftoning – 2 October 2011 1.13 Overview of Printing Technologies InkJet printhead Diagram courtesy Hewlett-Packard Co.
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This note was uploaded on 02/19/2012 for the course ECE 638 taught by Professor Staff during the Fall '08 term at Purdue.

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22. Halftoning_fundamentals - 2011 - 1 Halftoning...

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