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<?xml version="1.0" encoding="utf-8"?>
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<page xmlns="http://projectmallard.org/1.0/" type="topic" id="color-whyimportant" xml:lang="vi">
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<link type="guide" xref="color"/>
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<desc>Color management is important for designers, photographers and artists.</desc>
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<name>Richard Hughes</name>
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<email>richard@hughsie.com</email>
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<include xmlns="http://www.w3.org/2001/XInclude" href="legal.xml"/>
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<title>Why is color management important?</title>
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Color management is the process of capturing a color using an input
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device, displaying it on a screen, and printing it all whilst managing
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the exact colors and the range of colors on each medium.
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The need for color management is probably explained best with a
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photograph of a bird on a frosty day in winter.
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<desc>A bird on a frosty wall as seen on the camera view-finder</desc>
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<media type="image" mime="image/png" src="figures/color-camera.png"/>
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Displays typically over-saturate the blue channel, making the images
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<desc>This is what the user sees on a typical business laptop screen</desc>
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<media type="image" mime="image/png" src="figures/color-display.png"/>
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Notice how the white is not 'paper white' and the black of the eye
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<desc>This is what the user sees when printing on a typical inkjet printer</desc>
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<media type="image" mime="image/png" src="figures/color-printer.png"/>
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The basic problem we have here is that each device is capable of
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handling a different range of colors.
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So while you might be able to take a photo of electric blue, most
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printers are not going to be able to reproduce it.
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Most image devices capture in RGB (Red, Green, Blue) and have
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to convert to CMYK (Cyan, Magenta, Yellow, and Black) to print.
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Another problem is that you can't have <em>white</em> ink, and so
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the whiteness can only be as good as the paper color.
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Another problem is units.
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Without specifying the scale on which a color is measured, we don't
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know if 100% red is near infrared or just the deepest red ink in the
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What is 50% red on your display is probably something like 62% on my
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It's like telling a person that you've just driven 7 units of
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distance, without the unit you don't know if that's 7 kilometers or
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In color, we refer to the units as gamut. Gamut is essentually the
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range of colors that can be reproduced.
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A device like a DSLR camera might have a very large gamut, being able
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to capture all the colors in a sunset, but a projector has a very
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small gamut and all the colors are going to look "washed out".
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In some cases we can <em>correct</em> the device response by altering
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the data we sent to the device but in other cases where that's not
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possible (you can't print electric blue) we need to show the user
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what the result is going to look like.
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For photographs it makes sense to use the full tonal range of a color
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device, to be able to make smooth changes in color.
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For other graphics you might want to match the color exactly, which
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is important if you're trying to print a custom mug with the Red Hat
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logo, that <em>has</em> to be the exact Red Hat Red.
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