for ( var i = 0; i < gridlines[axis].length; i++) {
y = halfDown(g.toDomYCoord(gridlines[axis][i], axis));
// Ignore the alpha value
for ( var i = 0; i < gridlines[axis].length; i++) {
y = halfDown(g.toDomYCoord(gridlines[axis][i], axis));
// Ignore the alpha value
var drawnPixeldown2 = Util.samplePixel(g.hidden_, x, y - 2).slice(0, 3);
var drawnPixeldown1 = Util.samplePixel(g.hidden_, x, y - 1).slice(0, 3);
var drawnPixel = Util.samplePixel(g.hidden_, x, y).slice(0, 3);
var drawnPixeldown2 = Util.samplePixel(g.hidden_, x, y - 2).slice(0, 3);
var drawnPixeldown1 = Util.samplePixel(g.hidden_, x, y - 1).slice(0, 3);
var drawnPixel = Util.samplePixel(g.hidden_, x, y).slice(0, 3);