src/org/tiefaces/components/websheet/utility/ColorUtility.java
private static double getAutomaticTint(final int index) {

		final double[] idxArray = { 0, 0.25, 0.5, -0.25, -0.5, 0.1, 0.3,
				-0.1, -0.3 };
		int i = index / AUTOCOLORSIZE;
		if (i >= idxArray.length) {
			return 0;
		} else {
			return idxArray[i];
		}
	}
private static double getAutomaticTint(final int index) {

		final double[] idxArray = { 0, 0.25, 0.5, -0.25, -0.5, 0.1, 0.3,
				-0.1, -0.3 };
		int i = index / AUTOCOLORSIZE;
		if (i >= idxArray.length) {
			return 0;
		} else {
			return idxArray[i];
		}
	}
Get automatic tint number for specified index line. The default automatic
color only have 6 colors. If there are more than 6 lines then use tint
for next round, e.g. color7 = color1 + tint (0.25)

@param index
line index.
@return tint.