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[css-color-4] give deltaE2000 values for MacBeth patches
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‎css-color-4/Overview.bs‎

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@@ -56,6 +56,13 @@ table.named-color-table td:nth-child(n+4) { background: silver; }
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.color-table th { white-space: pre-line; }
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.color-table td { background: currentcolor; }
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.color-table .white { color: white; }
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table.deltaE td {border: 4px solid white; padding: 6px; font-size: 1.4em;}
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table.deltaE td.dE0 { background: rgb(68, 243, 91)}
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table.deltaE td.dE1 { background: rgb(153, 243, 68)}
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table.deltaE td.dE2 { background: rgb(217, 243, 68)}
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table.deltaE td.dE3 { background: rgb(243, 240, 68)}
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table.deltaE td.dE4 { background: rgb(243, 202, 68)}
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table.deltaE td.dE5 { background: rgb(243, 103, 68); color: white}
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</style>
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<h2 id="introduction">
@@ -2303,7 +2310,7 @@ Converting CMYK colors to Lab
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Conversion from a calibrated CMYK colorspace to Lab
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is typically dones by looking up the Lab values in an ICC profile.
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<h3 id="cmyk-to-lab">
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<h3 id="lab-to-cmyk">
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Converting Lab colors to CMYK
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</h3>
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@@ -3050,17 +3057,52 @@ can proceed as normal.
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<figure>
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<img src="images/macbeth-roundtrip.svg" style="width: 60vmin">
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<figcaption>
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A color checker, used for ensuring color fidelity
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<p>A color checker, used for ensuring color fidelity
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in the print and photographic industries.
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Averaged measured Lab values are available for each patch.
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The rectangles show the Lab values, converted to sRGB.
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The circles, which are barely visible, show the Lab values,
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passed through an ICC profile to convert them to CMYK.
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The CMYK values are then passed through the same ICC profile in reverse,
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to yield new Lab values. These are then converted to sRGB for display.
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The one patch with a more visible circle (third row, first patch)
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to yield new Lab values. These are then converted to sRGB for display.</p>
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<p>The one patch with a more visible circle (third row, first patch)
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is because the color is slightly outside the gamut of the
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FOGRA55 CMYK space used.
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FOGRA55 CMYK space used.</p>
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<p>The table below shows, for each patch, the DeltaE 2000 between the original Lab and the Lab value after round-tripping through CMYK. A DeltaE 2000 of 1 or more is just visible.</p>
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<table class="deltaE">
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<tr>
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<td class="dE0">0.06</td>
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<td class="dE0">0.07</td>
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<td class="dE0">0.03</td>
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<td class="dE0">0.04</td>
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<td class="dE0">0.06</td>
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<td class="dE0">0.17</td>
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</tr>
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<tr>
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<td class="dE0">0.03</td>
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<td class="dE0">0.75</td>
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<td class="dE0">0.05</td>
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<td class="dE0">0.06</td>
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<td class="dE0">0.03</td>
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<td class="dE0">0.02</td>
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</tr>
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<tr>
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<td class="dE2">1.9</td>
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<td class="dE0">0.04</td>
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<td class="dE0">0.06</td>
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<td class="dE0">0.05</td>
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<td class="dE0">0.02</td>
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<td class="dE0">0.05</td>
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</tr>
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<tr>
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<td class="dE0">0.03</td>
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<td class="dE0">0.08</td>
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<td class="dE0">0.03</td>
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<td class="dE0">0.03</td>
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<td class="dE0">0.04</td>
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<td class="dE0">0.80</td>
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</tr>
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</table>
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</figcaption>
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</figure>
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@@ -3325,12 +3367,47 @@ Device-dependent CMYK Colors: the ''device-cmyk()'' function</h2>
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<figure>
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<img src="images/macbeth-naive.svg" style="width: 60vmin">
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<figcaption>
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A color checker, used for ensuring color fidelity
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<p>A color checker, used for ensuring color fidelity
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in the print and photographic industries.
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Averaged measured Lab values are available for each patch.
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The rectangles show the Lab values, converted to sRGB.
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The circles show the Lab values, passed through an ICC profile to convert them to CMYK.
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The CMYK value are then naively converted to sRGB.
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The CMYK value are then naively converted to sRGB.</p>
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<p>The table below shows, for each patch, the DeltaE 2000 between the original Lab and the Lab value after round-tripping through CMYK. A DeltaE 2000 of 1 or more is just visible, while 5 or more is just a different color altogether.</p>
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<table class="deltaE">
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<tr>
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<td class="dE5">11.33</td>
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<td class="dE5">9.36</td>
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<td class="dE5">5.66</td>
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<td class="dE5">7.52</td>
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<td class="dE5">12.39</td>
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<td class="dE5">21.58</td>
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</tr>
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<tr>
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<td class="dE5">6.40</td>
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<td class="dE5">8.79</td>
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<td class="dE5">11.77</td>
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<td class="dE5">17.16</td>
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<td class="dE5">11.91</td>
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<td class="dE3">3.97</td>
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</tr>
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<tr>
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<td class="dE5">12.1</td>
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<td class="dE5">17.00</td>
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<td class="dE3">3.38</td>
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<td class="dE1">1.94</td>
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<td class="dE5">18.08</td>
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<td class="dE5">14.97</td>
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</tr>
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<tr>
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<td class="dE1">1.89</td>
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<td class="dE5">6.56</td>
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<td class="dE5">7.85</td>
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<td class="dE5">8.76</td>
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<td class="dE5">9.82</td>
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<td class="dE5">10.29</td>
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</tr>
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</table>
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</figcaption>
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</figure>
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