parser.addVariable("b", 0.0);
parser.addVariable("x", 0.0);
parser.addVariable("y", 0.0);
parser.addVariable("width", (double) width);
parser.addVariable("height", (double) height);
Node redNode = parser.parse(formula1Red);
Node greenNode = parser.parse(formula2Green);
Node blueNode = parser.parse(formula3Blue);
Pixel pixel = new Pixel();
for (int i = 0; i < height; i++) {
parser.setVarValue("y", i);
for (int j = 0; j < width; j++) {