diff --git a/src/org/oscim/utils/FastMath.java b/src/org/oscim/utils/FastMath.java
index a20a3c2a..b1aaf269 100644
--- a/src/org/oscim/utils/FastMath.java
+++ b/src/org/oscim/utils/FastMath.java
@@ -54,31 +54,40 @@ public class FastMath {
 
 		return (pow > 0 ? (1 << pow) : (1.0f / (1 << -pow)));
 	}
-	public static int clamp(int value, int max, int min){
+
+	public static int clamp(int value, int max, int min) {
 		return (value < min ? min : (value > max ? max : value));
 	}
 
-	public static byte clampToByte(int value){
-		return (byte)(value < 0 ? 0 : (value > 255 ? 255 : value));
+	public static float clamp(float value, float max, float min) {
+		return (value < min ? min : (value > max ? max : value));
 	}
 
-	public static float abs(float value){
+	public static float clampN(float value) {
+		return (value < 0f ? 0f : (value > 1f ? 1f : value));
+	}
+
+	public static byte clampToByte(int value) {
+		return (byte) (value < 0 ? 0 : (value > 255 ? 255 : value));
+	}
+
+	public static float abs(float value) {
 		return value < 0 ? -value : value;
 	}
 
-	public static float absMax(float value1, float value2){
+	public static float absMax(float value1, float value2) {
 		float a1 = value1 < 0 ? -value1 : value1;
 		float a2 = value2 < 0 ? -value2 : value2;
 		return a2 < a1 ? a1 : a2;
 	}
 
 	// test if any absolute value is greater than 'cmp'
-	public static boolean absMaxCmp(float value1, float value2, float cmp){
+	public static boolean absMaxCmp(float value1, float value2, float cmp) {
 		return value1 < -cmp || value1 > cmp || value2 < -cmp || value2 > cmp;
 	}
 
 	// test if any absolute value is greater than 'cmp'
-	public static boolean absMaxCmp(int value1, int value2, int cmp){
+	public static boolean absMaxCmp(int value1, int value2, int cmp) {
 		return value1 < -cmp || value1 > cmp || value2 < -cmp || value2 > cmp;
 	}
 }
diff --git a/src/org/oscim/utils/GlUtils.java b/src/org/oscim/utils/GlUtils.java
index 7ca30816..55a06fd0 100644
--- a/src/org/oscim/utils/GlUtils.java
+++ b/src/org/oscim/utils/GlUtils.java
@@ -257,6 +257,29 @@ public class GlUtils {
 		return c;
 	}
 
+	/**
+	 * public-domain function by Darel Rex Finley
+	 * from http://alienryderflex.com/saturation.html
+	 *
+	 * @param color
+	 *            The passed-in RGB values can be on any desired scale, such as
+	 *            0 to 1, or 0 to 255.
+	 * @param change
+	 *            0.0 creates a black-and-white image.
+	 *            0.5 reduces the color saturation by half.
+	 *            1.0 causes no change.
+	 *            2.0 doubles the color saturation.
+	 */
+	public static void changeSaturation(float color[], float change) {
+		float r = color[0];
+		float g = color[1];
+		float b = color[2];
+		double p = Math.sqrt(r * r * 0.299f + g * g * 0.587f + b * b * 0.114f);
+		color[0] = FastMath.clampN((float) (p + (r - p) * change));
+		color[1] = FastMath.clampN((float) (p + (g - p) * change));
+		color[2] = FastMath.clampN((float) (p + (b - p) * change));
+	}
+
 	private final static float[] mIdentity = {
 			1, 0, 0, 0,
 			0, 1, 0, 0,