RRLuminanceFromRGBComponents.m

// RRUtils RRLuminanceFromRGBComponents.m
//
// Copyright © 2008-2010, Roy Ratcliffe, Pioneering Software, United Kingdom
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//
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// of this software and associated documentation files (the "Software"), to deal
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// copies of the Software, and to permit persons to whom the Software is
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//------------------------------------------------------------------------------

#import "RRLuminanceFromRGBComponents.h"

// http://www.opengl.org/resources/code/samples/advanced/advanced97/notes/node140.html
CGFloat RRLuminanceFromRGBComponents(const CGFloat *rgb)
{
	// 0.3086 + 0.6094 + 0.0820 = 1.0
	return 0.3086f*rgb[0] + 0.6094f*rgb[1] + 0.0820f*rgb[2];
}