if(!window.Color) Color = { };
if(!window.Color.Vision) Color.Vision = { };

(function() {

/*
	Color.Vision.Daltonize : v0.1
	------------------------------
	"Analysis of Color Blindness" by Onur Fidaner, Poliang Lin and Nevran Ozguven.
	http://scien.stanford.edu/class/psych221/projects/05/ofidaner/project_report.pdf
	
	"Digital Video Colourmaps for Checking the Legibility of Displays by Dichromats" by Françoise Viénot, Hans Brettel and John D. Mollon
	http://vision.psychol.cam.ac.uk/jdmollon/papers/colourmaps.pdf

*/

var CVDMatrix = { // Color Vision Deficiency
	"Protanope": [ // reds are greatly reduced (1% men)
		0.0, 2.02344, -2.52581,
		0.0, 1.0,      0.0,
		0.0, 0.0,      1.0
	],
	"Deuteranope": [ // greens are greatly reduced (1% men)
		1.0,      0.0, 0.0,
		0.494207, 0.0, 1.24827,
		0.0,      0.0, 1.0
	],
	"Tritanope": [ // blues are greatly reduced (0.003% population)
		1.0,       0.0,      0.0,
		0.0,       1.0,      0.0,
		-0.395913, 0.801109, 0.0
	]
};

Color.Vision.Daltonize = function(image, options) {
	if(!options) options = { };
	var type = typeof options.type == "string" ? options.type : "Normal", 
		amount = typeof options.amount == "number" ? options.amount : 1.0,
		canvas = document.createElement("canvas"),
		ctx = canvas.getContext("2d");
	canvas.width = image.width;
	canvas.height = image.height;
	ctx.drawImage(image, 0, 0);
	try {
		var imageData = ctx.getImageData(0, 0, canvas.width, canvas.height),
			data = imageData.data;		
	} catch(e) { }
	// Apply Daltonization
	var cvd = CVDMatrix[type],
		cvd_a = cvd[0],
		cvd_b = cvd[1],
		cvd_c = cvd[2],
		cvd_d = cvd[3],
		cvd_e = cvd[4],
		cvd_f = cvd[5],
		cvd_g = cvd[6],
		cvd_h = cvd[7],
		cvd_i = cvd[8];
	var L, M, S, l, m, s, R, G, B, RR, GG, BB;
	for(var id = 0, length = data.length; id < length; id += 4) {
		var r = data[id],
			g = data[id + 1],
			b = data[id + 2];
		// RGB to LMS matrix conversion
		L = (17.8824 * r) + (43.5161 * g) + (4.11935 * b);
		M = (3.45565 * r) + (27.1554 * g) + (3.86714 * b);
		S = (0.0299566 * r) + (0.184309 * g) + (1.46709 * b);
		// Simulate color blindness
		l = (cvd_a * L) + (cvd_b * M) + (cvd_c * S);
		m = (cvd_d * L) + (cvd_e * M) + (cvd_f * S);
		s = (cvd_g * L) + (cvd_h * M) + (cvd_i * S);
		// LMS to RGB matrix conversion
		R = (0.0809444479 * l) + (-0.130504409 * m) + (0.116721066 * s);
		G = (-0.0102485335 * l) + (0.0540193266 * m) + (-0.113614708 * s);
		B = (-0.000365296938 * l) + (-0.00412161469 * m) + (0.693511405 * s);
		// Isolate invisible colors to color vision deficiency (calculate error matrix)
		R = r - R;
		G = g - G;
		B = b - B;
		// Shift colors towards visible spectrum (apply error modifications)
		RR = (0.0 * R) + (0.0 * G) + (0.0 * B);
		GG = (0.7 * R) + (1.0 * G) + (0.0 * B);
		BB = (0.7 * R) + (0.0 * G) + (1.0 * B);
		// Add compensation to original values
		R = RR + r;
		G = GG + g;
		B = BB + b;
		// Clamp values
		if(R < 0) R = 0;
		if(R > 255) R = 255;
		if(G < 0) G = 0;
		if(G > 255) G = 255;
		if(B < 0) B = 0;
		if(B > 255) B = 255;
		// Record color
		data[id] = R >> 0;
		data[id + 1] = G >> 0;
		data[id + 2] = B >> 0;
	}
	// Record data
	ctx.putImageData(imageData, 0, 0);
	if(typeof options.callback == "function") {
		options.callback(canvas);
	}
};

})();