Changeset 2014


Ignore:
Timestamp:
Nov 17, 2007, 4:02:59 PM (13 years ago)
Author:
Sam Hocevar
Message:
  • Put a few keywords in bold.
File:
1 edited

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  • www/study/part2.html

    r2013 r2014  
    113113
    114114<p> Different matrices can give very different results. This is a 4×4
    115 Bayer ordered dithering matrix: </p>
     115<b>Bayer ordered dither matrix</b>: </p>
    116116
    117117<p style="text-align: center;">
     
    135135</p>
    136136
    137 <p> This 4×4 cluster dot matrix creates dot patterns: </p>
     137<p> This 4×4 <b>cluster dot matrix</b> creates dot patterns: </p>
    138138
    139139<p style="text-align: center;">
     
    190190</p>
    191191
    192 <p> This is random dithering with threshold values chosen with a gaussian
    193 distribution (mean 0.5, standard deviation 0.15): </p>
     192<p> This is random dithering with threshold values chosen with a <b>gaussian
     193distribution</b> (mean 0.5, standard deviation 0.15): </p>
    194194
    195195<p style="text-align: center;">
     
    202202<p> Random dithering can help reduce the major problem caused by halftoning,
    203203which is the apparition of pattern artifacts. The method is as simple as
    204 slightly perturbating matrix coefficients (or pixel values) during the
    205 halftoning step. The difficult part is the proper pertubation choice. </p>
     204<b>slightly perturbating dither matrix coefficients</b> (or pixel values)
     205during the halftoning step. The difficult part is picking up an adequate
     206perturbation function: too much perturbation and the result is unrecognisable,
     207too little and the artifacts stay. </p>
    206208
    207209<p> For instance, this is the result of 8×8 Bayer dithering perturbated by a
     
    216218
    217219<p> Another way to use random number generators to avoid pattern artifacts
    218 is random dither matrix selection. The image space is no longer tiled with
    219 the same matrix over and over again, but with a random selection from a list
    220 of similar dither matrices. </p>
     220is <b>random dither matrix selection</b>. The image space is no longer tiled
     221with the same matrix over and over again, but with a random selection from a
     222list of similar dither matrices. </p>
    221223
    222224<p> This example shows random matrix selection from a list of six 3×3 dither
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