diff --git a/src/03/gammacorrection.ts b/src/03/gammacorrection.ts
index 4443a90..5e8e689 100644
--- a/src/03/gammacorrection.ts
+++ b/src/03/gammacorrection.ts
@@ -15,4 +15,16 @@ export function gammaAdjust(gamma: number, source: Uint8ClampedArray,
                             width: number, height: number) {
 
     // TODO: Perform a gamma correction with the given gamma value on the current pixel at position (x, y) in the source array, and store the result in the dest array.
+    var posInArrayX = x * 4;
+    var posInArrayY = y * 4 * width;
+    
+    var R = source[0 + posInArrayX + posInArrayY];
+    var G = source[1 + posInArrayX + posInArrayY];
+    var B = source[2 + posInArrayX + posInArrayY];
+    var A = source[3 + posInArrayX + posInArrayY];
+    
+    dest[0 + posInArrayX + posInArrayY] = Math.pow((R/256),(1/gamma))*256;
+    dest[1 + posInArrayX + posInArrayY] = Math.pow((G/256),(1/gamma))*256;
+    dest[2 + posInArrayX + posInArrayY] = Math.pow((B/256),(1/gamma))*256;
+    dest[3 + posInArrayX + posInArrayY] = A;
 }
diff --git a/src/03/grayscale.ts b/src/03/grayscale.ts
index f11d074..2823179 100644
--- a/src/03/grayscale.ts
+++ b/src/03/grayscale.ts
@@ -13,4 +13,19 @@ export function grayscale(x: number, y: number, source: Uint8ClampedArray, targe
 
     // TODO: Convert the pixel at position (x, y) in the source array from RGB to XYZ.
     // TODO: Set the RGBA values in the target array according to the Y component of the source pixel in XYZ space.
+    var posInArrayX = x * 4;
+    var posInArrayY = y * 4 * width;
+    var matrix = [  0.4124564, 0.3575761, 0.1804375, 
+                    0.2126729, 0.7151522, 0.0721750,
+                    0.0193339, 0.1191920, 0.9503041];
+    
+    var R = source[0 + posInArrayX + posInArrayY];
+    var G = source[1 + posInArrayX + posInArrayY];
+    var B = source[2 + posInArrayX + posInArrayY];
+    var A = source[3 + posInArrayX + posInArrayY];
+    
+    target[0 + posInArrayX + posInArrayY] = Math.abs(matrix[3]*R + matrix[4]*G + matrix[5]*B); // (R+B+G)/3;
+    target[1 + posInArrayX + posInArrayY] = Math.abs(matrix[3]*R + matrix[4]*G + matrix[5]*B); // (R+B+G)/3;
+    target[2 + posInArrayX + posInArrayY] = Math.abs(matrix[3]*R + matrix[4]*G + matrix[5]*B); // (R+B+G)/3;
+    target[3 + posInArrayX + posInArrayY] = A;
 }
diff --git a/src/03/quantisecolor.ts b/src/03/quantisecolor.ts
index 0273860..9eeea44 100644
--- a/src/03/quantisecolor.ts
+++ b/src/03/quantisecolor.ts
@@ -14,4 +14,17 @@ export function quantiseColor(x: number, y: number, source: Uint8ClampedArray, t
     // TODO: Limit the brightness of each color channel to the set of 4 different values 0, 85, 170, 255.
     // TODO: Set the RGBA values in the target array accordingly.
     // TODO:
+    var posInArrayX = x * 4;
+    var posInArrayY = y * 4 * width;
+    
+    var R = source[0 + posInArrayX + posInArrayY];
+    var G = source[1 + posInArrayX + posInArrayY];
+    var B = source[2 + posInArrayX + posInArrayY];
+    var A = source[3 + posInArrayX + posInArrayY];
+
+    //quantisierung
+    for(let i = 0; i < 3; i++) {
+        target[i + posInArrayX + posInArrayY] = (Math.floor((source[i + posInArrayX + posInArrayY]/256) * (4))) * (256/3);
+    }
+    target[3 + posInArrayX + posInArrayY] = A;
 }
diff --git a/src/03/quantisegrayscale.ts b/src/03/quantisegrayscale.ts
index d3c1c2f..bc352af 100644
--- a/src/03/quantisegrayscale.ts
+++ b/src/03/quantisegrayscale.ts
@@ -14,4 +14,28 @@ export function quantisegrayscale(x: number, y: number, source: Uint8ClampedArra
     // TODO: Convert the pixel at position (x, y) in the source array from RGB to XYZ. Limit the 
     // TODO: Limit the brightness to the set of 4 different values 0, 85, 170, 255.
     // TODO: Set the RGBA values in the target array to this brightness.
+    var posInArrayX = x * 4;
+    var posInArrayY = y * 4 * width;
+    var matrix = [  0.4124564, 0.3575761, 0.1804375, 
+                    0.2126729, 0.7151522, 0.0721750,
+                    0.0193339, 0.1191920, 0.9503041];
+    
+    var R = source[0 + posInArrayX + posInArrayY];
+    var G = source[1 + posInArrayX + posInArrayY];
+    var B = source[2 + posInArrayX + posInArrayY];
+    var A = source[3 + posInArrayX + posInArrayY];
+    
+    var X = 0;
+    var Y = Math.abs(matrix[3]*R + matrix[4]*G + matrix[5]*B)
+    var Z = 0;
+
+    //quantisierung
+    let QY = (Y/256) * (4);
+    QY = Math.floor(QY);
+    QY = QY * (256/3);
+    
+    target[0 + posInArrayX + posInArrayY] = QY;
+    target[1 + posInArrayX + posInArrayY] = QY;
+    target[2 + posInArrayX + posInArrayY] = QY;
+    target[3 + posInArrayX + posInArrayY] = A;
 }