Transform between RGB and XYZ colours with come calculations I found on the web

RGB-XYZ.c

#include <CoreGraphics/CoreGraphics.h>

static inline CGFloat gammaCorrect(CGFloat component) {
	if (component > 0.04045f) {
		return pow((component + 0.055f) / 1.055f, 2.4f);
	}

	return component / 12.92f;
}

static inline CGFloat reverseGammaCorrect(CGFloat component) {
	if (component > 0.0031308) {
		return 1.055f * pow(component, 1 / 2.4f) - 0.055f;
	}

	return component * 12.92f;
}

static void RGBToXYZ(CGFloat red, CGFloat green, CGFloat blue, CGFloat *X, CGFloat *Y, CGFloat *Z) {
	// http://www.easyrgb.com/index.php?X=MATH&H=02#text2

	CGFloat correctedRed = gammaCorrect(red);
	CGFloat correctedGreen = gammaCorrect(green);
	CGFloat correctedBlue = gammaCorrect(blue);

	// Observer = 2°, Illuminant = D65
	if (X) *X = correctedRed * 0.4124f + correctedGreen * 0.3576f + correctedBlue * 0.1805f;
	if (Y) *Y = correctedRed * 0.2126f + correctedGreen * 0.7152f + correctedBlue * 0.0722f;
	if (Z) *Z = correctedRed * 0.0193f + correctedGreen * 0.1192f + correctedBlue * 0.9505f;
}

static void XYZToRGB(CGFloat X, CGFloat Y, CGFloat Z, CGFloat *red, CGFloat *green, CGFloat *blue) {
	// http://www.easyrgb.com/index.php?X=MATH&H=01#text1

	// Observer = 2°, Illuminant = D65
	CGFloat correctedRed   = X *  3.2406f + Y * -1.5372f + Z * -0.4986f;
	CGFloat correctedGreen = X * -0.9689f + Y *  1.8758f + Z *  0.0415f;
	CGFloat correctedBlue  = X *  0.0557f + Y * -0.2040f + Z *  1.0570f;

	if (red) *red = reverseGammaCorrect(correctedRed);
	if (green) *green = reverseGammaCorrect(correctedGreen);
	if (blue) *blue = reverseGammaCorrect(correctedBlue);
}

int main(int argc, char *argv[]) {
	CGFloat X, Y, Z;
	RGBToXYZ(1, 0.5, 0.1, &X, &Y, &Z);
	CGFloat red, green, blue;
	XYZToRGB(X, Y, Z, &red, &green, &blue);

	printf("RGB(%g, %g, %g)\n", red, green, blue);
	
	return 0;
}