49 lines
2.2 KiB
HTML
Executable File
49 lines
2.2 KiB
HTML
Executable File
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<html>
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<head>
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<title>Input vs. Output Referred images</title>
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<meta http-equiv="content-type" content="text/html;
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charset=windows-1252">
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</head>
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<body>
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<h2 style="text-decoration: underline; font-weight: bold;">Input vs.
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Output Referred Images<br>
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</h2>
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A lot of Photography related sources recommend that images be
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encoded in a large gamut colorspace such as ProPhoto, but don't
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explain the implications of doing this in in the process of
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subsequently displaying such photo's. <br>
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<h3> Input referred:</h3>
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Images are encoded in a way that represents their unchanged or
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originally captured values, in an encoding space that is larger
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enough to store their gamut without clipping. The gamut of the
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encoding space tells you nothing about the gamut of the images.<br>
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<br>
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Typical: L*a*b*, Raw, ProPhoto, RIMM etc.<br>
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<h3>Output referred:</h3>
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Images are modified (i.e. rendered) to fit within the gamut of a
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specific real world output device (such as display or printer). This
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means that typically the encoding space is a good representation of
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the gamut of the images.<br>
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<br>
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Typical sRGB, AdobeRGB, printer profile, display profile, etc.<br>
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<br>
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<br>
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Before displaying images that are Input Referred, they need to be
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rendered to a smaller gamut. This may be done manually by adjusting
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the images carefully to fit within the smaller gamut, or in some
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automatic fashion such as by hard clipping them to the smaller
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gamut, or by setting up a specific gamut mapping for each image or
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set of images that occupy a similar gamut.<br>
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<br>
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<u><b>Note</b></u> that setting up a gamut mapping from the very
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large Input referred encoding gamut to the smaller output device
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gamut will almost certainly result in a disappointing loss of
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saturation, because the images deliberately do not occupy the large
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encoding gamut, and so get unnecessarily squashed down to allow for
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colors that they do not actually contain.<br>
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<br>
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See also Scenarios.html#LP3.<br>
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</body>
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</html>
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