trig.cpp

/*
 * Copyright (c) 2007 Alexander Strange <astrange@ithinksw.com>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include "trig.h"

real srgbToL[256];

static inline real linearFromSRGB(uint8_t vi)
{
	const real a = .055, v = vi/255.;
	real v_linear = (v > .04045) ? pow((v + a) / 1.055, 2.4) : (v / 12.92); 
	return v_linear;
}

static struct srgbToLSetup
{
	srgbToLSetup()
	{
		for (int i = 0; i < 256; i++)
			srgbToL[i] = linearFromSRGB(i);
	}
} srgbsetup;