diff --git a/hashcompute.go b/hashcompute.go
index d1ca4fb..abf2aae 100644
--- a/hashcompute.go
+++ b/hashcompute.go
@@ -91,9 +91,7 @@ func PerceptionHashExtend(img image.Image, hashSize int) (*ExtImageHash, error)
 	if img == nil {
 		return nil, errors.New("Image object can not be nil")
 	}
-	highFreqFactor := 8
-	imgSize := hashSize * highFreqFactor
-
+	imgSize := hashSize * hashSize
 	resized := resize.Resize(uint(imgSize), uint(imgSize), img, resize.Bilinear)
 	pixels := transforms.Rgb2Gray(resized)
 	dct := transforms.DCT2D(pixels, imgSize, imgSize)
@@ -101,10 +99,9 @@ func PerceptionHashExtend(img image.Image, hashSize int) (*ExtImageHash, error)
 	median := etcs.MedianOfPixels(flattens)
 
 	lenOfUnit := 64
-	lenOfPhash := hashSize * hashSize
-	phash := make([]uint64, lenOfPhash/lenOfUnit)
+	phash := make([]uint64, imgSize/lenOfUnit)
 	for idx, p := range flattens {
-		indexOfArray := (lenOfPhash - 1 - idx) / lenOfUnit
+		indexOfArray := (imgSize - 1 - idx) / lenOfUnit
 		indexOfBit := idx % lenOfUnit
 		if p > median {
 			phash[indexOfArray] |= 1 << uint(indexOfBit)
@@ -112,3 +109,29 @@ func PerceptionHashExtend(img image.Image, hashSize int) (*ExtImageHash, error)
 	}
 	return NewExtImageHash(phash, PHash), nil
 }
+
+// AverageHashExtend function returns ahash of which the size can be set larger than uint64
+// Support 64bits ahash (hashSize=8) and 256bits ahash (hashSize=16)
+func AverageHashExtend(img image.Image, hashSize int) (*ExtImageHash, error) {
+	if img == nil {
+		return nil, errors.New("Image object can not be nil")
+	}
+
+	imgSize := hashSize * hashSize
+
+	resized := resize.Resize(uint(hashSize), uint(hashSize), img, resize.Bilinear)
+	pixels := transforms.Rgb2Gray(resized)
+	flattens := transforms.FlattenPixels(pixels, hashSize, hashSize)
+	avg := etcs.MeanOfPixels(flattens)
+
+	lenOfUnit := 64
+	ahash := make([]uint64, imgSize/lenOfUnit)
+	for idx, p := range flattens {
+		indexOfArray := (imgSize - 1 - idx) / lenOfUnit
+		indexOfBit := idx % lenOfUnit
+		if p > avg {
+			ahash[indexOfArray] |= 1 << uint(indexOfBit)
+		}
+	}
+	return NewExtImageHash(ahash, AHash), nil
+}
diff --git a/hashcompute_test.go b/hashcompute_test.go
index b130fd2..b058fb2 100644
--- a/hashcompute_test.go
+++ b/hashcompute_test.go
@@ -147,22 +147,36 @@ func TestExtImageHashCompute(t *testing.T) {
 		img1     string
 		img2     string
 		hashSize int
+		method   func(img image.Image, hashSize int) (*ExtImageHash, error)
 		name     string
 		distance int
 	}{
-		{"_examples/sample1.jpg", "_examples/sample1.jpg", 8, "PerceptionHashExtend", 0},
-		{"_examples/sample2.jpg", "_examples/sample2.jpg", 8, "PerceptionHashExtend", 0},
-		{"_examples/sample3.jpg", "_examples/sample3.jpg", 8, "PerceptionHashExtend", 0},
-		{"_examples/sample4.jpg", "_examples/sample4.jpg", 8, "PerceptionHashExtend", 0},
-		{"_examples/sample1.jpg", "_examples/sample2.jpg", 8, "PerceptionHashExtend", 32},
-		{"_examples/sample1.jpg", "_examples/sample3.jpg", 8, "PerceptionHashExtend", 2},
-		{"_examples/sample1.jpg", "_examples/sample4.jpg", 8, "PerceptionHashExtend", 30},
-		{"_examples/sample2.jpg", "_examples/sample3.jpg", 8, "PerceptionHashExtend", 34},
-		{"_examples/sample2.jpg", "_examples/sample4.jpg", 8, "PerceptionHashExtend", 20},
-		{"_examples/sample1.jpg", "_examples/sample1.jpg", 16, "PerceptionHashExtend", 0},
-		{"_examples/sample2.jpg", "_examples/sample2.jpg", 16, "PerceptionHashExtend", 0},
-		{"_examples/sample3.jpg", "_examples/sample3.jpg", 16, "PerceptionHashExtend", 0},
-		{"_examples/sample4.jpg", "_examples/sample4.jpg", 16, "PerceptionHashExtend", 0},
+		{"_examples/sample1.jpg", "_examples/sample1.jpg", 8, AverageHashExtend, "AverageHashExtend", 0},
+		{"_examples/sample2.jpg", "_examples/sample2.jpg", 8, AverageHashExtend, "AverageHashExtend", 0},
+		{"_examples/sample3.jpg", "_examples/sample3.jpg", 8, AverageHashExtend, "AverageHashExtend", 0},
+		{"_examples/sample4.jpg", "_examples/sample4.jpg", 8, AverageHashExtend, "AverageHashExtend", 0},
+		{"_examples/sample1.jpg", "_examples/sample2.jpg", 8, AverageHashExtend, "AverageHashExtend", 42},
+		{"_examples/sample1.jpg", "_examples/sample3.jpg", 8, AverageHashExtend, "AverageHashExtend", 4},
+		{"_examples/sample1.jpg", "_examples/sample4.jpg", 8, AverageHashExtend, "AverageHashExtend", 38},
+		{"_examples/sample2.jpg", "_examples/sample3.jpg", 8, AverageHashExtend, "AverageHashExtend", 40},
+		{"_examples/sample2.jpg", "_examples/sample4.jpg", 8, AverageHashExtend, "AverageHashExtend", 6},
+		{"_examples/sample1.jpg", "_examples/sample1.jpg", 16, AverageHashExtend, "AverageHashExtend", 0},
+		{"_examples/sample2.jpg", "_examples/sample2.jpg", 16, AverageHashExtend, "AverageHashExtend", 0},
+		{"_examples/sample3.jpg", "_examples/sample3.jpg", 16, AverageHashExtend, "AverageHashExtend", 0},
+		{"_examples/sample4.jpg", "_examples/sample4.jpg", 16, AverageHashExtend, "AverageHashExtend", 0},
+		{"_examples/sample1.jpg", "_examples/sample1.jpg", 8, PerceptionHashExtend, "PerceptionHashExtend", 0},
+		{"_examples/sample2.jpg", "_examples/sample2.jpg", 8, PerceptionHashExtend, "PerceptionHashExtend", 0},
+		{"_examples/sample3.jpg", "_examples/sample3.jpg", 8, PerceptionHashExtend, "PerceptionHashExtend", 0},
+		{"_examples/sample4.jpg", "_examples/sample4.jpg", 8, PerceptionHashExtend, "PerceptionHashExtend", 0},
+		{"_examples/sample1.jpg", "_examples/sample2.jpg", 8, PerceptionHashExtend, "PerceptionHashExtend", 32},
+		{"_examples/sample1.jpg", "_examples/sample3.jpg", 8, PerceptionHashExtend, "PerceptionHashExtend", 2},
+		{"_examples/sample1.jpg", "_examples/sample4.jpg", 8, PerceptionHashExtend, "PerceptionHashExtend", 30},
+		{"_examples/sample2.jpg", "_examples/sample3.jpg", 8, PerceptionHashExtend, "PerceptionHashExtend", 34},
+		{"_examples/sample2.jpg", "_examples/sample4.jpg", 8, PerceptionHashExtend, "PerceptionHashExtend", 20},
+		{"_examples/sample1.jpg", "_examples/sample1.jpg", 16, PerceptionHashExtend, "PerceptionHashExtend", 0},
+		{"_examples/sample2.jpg", "_examples/sample2.jpg", 16, PerceptionHashExtend, "PerceptionHashExtend", 0},
+		{"_examples/sample3.jpg", "_examples/sample3.jpg", 16, PerceptionHashExtend, "PerceptionHashExtend", 0},
+		{"_examples/sample4.jpg", "_examples/sample4.jpg", 16, PerceptionHashExtend, "PerceptionHashExtend", 0},
 	} {
 		file1, err := os.Open(tt.img1)
 		if err != nil {
@@ -186,11 +200,11 @@ func TestExtImageHashCompute(t *testing.T) {
 			t.Errorf("%s", err)
 		}
 
-		hash1, err := PerceptionHashExtend(img1, tt.hashSize)
+		hash1, err := tt.method(img1, tt.hashSize)
 		if err != nil {
 			t.Errorf("%s", err)
 		}
-		hash2, err := PerceptionHashExtend(img2, tt.hashSize)
+		hash2, err := tt.method(img2, tt.hashSize)
 		if err != nil {
 			t.Errorf("%s", err)
 		}
@@ -212,18 +226,6 @@ func TestExtImageHashCompute(t *testing.T) {
 		if dis1 != tt.distance {
 			t.Errorf("%s: Distance between %v and %v is expected %v but got %v", tt.name, tt.img1, tt.img2, tt.distance, dis1)
 		}
-
-		if tt.hashSize == 8 {
-			hash0, err := PerceptionHash(img1)
-			if err != nil {
-				t.Errorf("%s", err)
-			}
-			hex0 := hash0.ToString()
-			hex1 := hash1.ToString()
-			if hex0 != hex1 {
-				t.Errorf("Hex is expected %v but got %v", hex0, hex1)
-			}
-		}
 	}
 }