UFRaw curve specifications

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UFRaw curve file has a .curve ending. It is an XML file and the structure can easily understood from an example: 

<?xml version="1.0" encoding="utf-8"?>
<Curve Version='7'>Sample
        <AnchorXY>0.180392 0.078431</AnchorXY>
        <AnchorXY>0.392157 0.478431</AnchorXY>
        <AnchorXY>0.627451 0.666667</AnchorXY>
        <AnchorXY>0.847059 0.956863</AnchorXY>
</Curve>

There is no limit on the number of anchor points, but UFRaw limits itself to 20 points, to match the limit of the Nikon Tone Curve (NTC) format.

The version number is ignored, but can not be larger than 7.

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Generating the curve

The curve is a constant line before the first point and after the last point. The inner curve is interpolated by a cubic spline.

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Applying the curve

How the curve is used is not part of the specification. UFRaw uses the same curve format for two different purposes -- the base curve and the luminosity curve.

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Other softwares that use this format

No other software is known to use this format. This means that the format can change without notice. Please update the UFRaw developer if you plan to use this format. Especially, if you want to keep compatility.

Retrieved from "http://ufraw.sourceforge.net/wiki/UFRaw_curve_specifications"
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