Fixed the hashing algorithm to use Longs and also added an AHash class

src/main/scala/com/sothr/imagetools/hash/AHash.scala

@@ -1,10 +1,48 @@
 package com.sothr.imagetools.hash
 
+import grizzled.slf4j.Logging
+
 /**
   * Created by dev on 1/22/14.
   */
-object AHash extends PerceptualHasher {
+object AHash extends PerceptualHasher with Logging {
    def getHash(imageData: Array[Array[Int]]): Long = {
-     return 0L
+     debug("Generating AHash")
+     val width = imageData.length
+     val height = imageData(0).length
+     debug(s"Image data size: ${width}x${height}")
+
+     //calculate average pixel
+     var total = 0
+     for (row <- 0 until height) {
+       for (col <- 0 until width) {
+         total += imageData(row)(col)
+       }
+     }
+     val mean = total / (height * width)
+
+     //calculate ahash
+     var hash = 0L
+     for (row <- 0 until height by 2) {
+       //process each column
+       for (col <- 0 until width by 1) {
+         hash <<= 1
+         val pixel = imageData(row)(col)
+         //If the current pixel is at or above the mean, store it as a one, else store it as a zero
+         if (pixel >= mean) hash |= 1 else hash |= 0
+       }
+
+       if ((row +1) < width) {
+         val nextRow = row + 1
+         //process each column
+         for (col <- (width - 1) to 0 by -1) {
+           hash <<= 1
+           val pixel = imageData(nextRow)(col)
+           if (pixel >= mean) hash |= 1 else hash |= 0
+         }
+       }
+     }
+     debug(s"Computed AHash: $hash from ${width * height} pixels")
+     hash
    }
  }

src/main/scala/com/sothr/imagetools/hash/DHash.scala

@@ -13,7 +13,7 @@ object DHash extends PerceptualHasher with Logging {
     debug(s"Image data size: ${width}x${height}")
     
     //calculate dhash
-    var hash = 0
+    var hash = 0L
     var previousPixel = imageData(height-1)(width-1)
     var previousLocation = (height-1, width-1)
     if (height % 2 == 0) {
@@ -27,10 +27,10 @@ object DHash extends PerceptualHasher with Logging {
         hash <<= 1
         val pixel = imageData(row)(col)
         //debug(s"previousPixel: $previousPixel currentPixel: $pixel previousLocation: $previousLocation currentLocation: (${row},${col})")
-        //binary or the current bit based on whether the value
+        //binary of the current bit based on whether the value
         //of the current pixel is greater or equal to the previous pixel
         if (pixel >= previousPixel) hash |= 1 else hash |= 0
-        //debug(s"hash: $hash")
+        //debug(s"(${row},${col})=$pixel hash=${hash.toBinaryString}")
         previousPixel = pixel
         previousLocation = (row, col)
       }
@@ -42,16 +42,14 @@ object DHash extends PerceptualHasher with Logging {
             hash <<= 1
             val pixel = imageData(nextRow)(col)
             //debug(s"previousPixel: $previousPixel currentPixel: $pixel previousLocation: $previousLocation currentLocation: (${nextRow},${col})")
-            //binary or the current bit based on whether the value
-            //of the current pixel is greater or equal to the previous pixel
             if (pixel >= previousPixel) hash |= 1 else hash |= 0
-            //debug(s"hash: $hash")
+            //debug(s"(${row},${col})=$pixel hash=${hash.toBinaryString}")
             previousPixel = pixel
             previousLocation = (nextRow, col)
           }
       }
     }
-    debug(s"Computed Hash: $hash from ${width * height} pixels")
+    debug(s"Computed DHash: $hash from ${width * height} pixels")
     hash
   }
 }

src/test/scala/com/sothr/imagetools/hash/HashServiceTest.scala

@@ -44,6 +44,21 @@ class HashServiceTest extends BaseTest {
       assert(true)
   }
 
+  test("Confirm Largest DHash Output ") {
+    val testData:Array[Array[Int]] = Array(
+      Array(1,2,3,4,5,6,7,8),
+      Array(16,15,14,13,12,11,10,9),
+      Array(17,18,19,20,21,22,23,24),
+      Array(32,31,30,29,28,27,26,25),
+      Array(33,34,35,36,37,38,39,40),
+      Array(48,47,46,45,44,43,42,41),
+      Array(49,50,51,52,53,54,55,56),
+      Array(64,63,62,61,60,59,58,57))
+    val hash = DHash.getHash(testData)
+    debug(s"Hash of test array: $hash")
+    assert(hash == (Long.MaxValue))
+  }
+
   test("Calculate DHash Large Sample Image 1") {
     debug("Starting 'Calculate DHash Large Sample Image 1' test")
     val sample = new File(TestParams.LargeSampleImage1)
@@ -51,8 +66,8 @@ class HashServiceTest extends BaseTest {
     val image = ImageIO.read(sample)
     debug(s"Image: width: ${image.getWidth} height: ${image.getHeight}")
     val hash = HashService.getDhash(image)
-    debug(s"Testing that $hash = -1689609389L")
-    assert(hash == -1689609389L)
+    debug(s"Testing that $hash = 4004374827879799635L")
+    assert(hash == 4004374827879799635L)
   }
   
   test("Calculate DHash Medium Sample Image 1") {
@@ -62,8 +77,8 @@ class HashServiceTest extends BaseTest {
     val image = ImageIO.read(sample)
     debug(s"Image: width: ${image.getWidth} height: ${image.getHeight}")
     val hash = HashService.getDhash(image)
-    debug(s"Testing that $hash = -1689609389L")
-    assert(hash == -1689609389L)
+    debug(s"Testing that $hash = 4004374827879799635L")
+    assert(hash == 4004374827879799635L)
   }
   
   test("Calculate DHash Small Sample Image 1") {
@@ -73,8 +88,8 @@ class HashServiceTest extends BaseTest {
     val image = ImageIO.read(sample)
     debug(s"Image: width: ${image.getWidth} height: ${image.getHeight}")
     val hash = HashService.getDhash(image)
-    debug(s"Testing that $hash = -1689609389L")
-    assert(hash == -1689609389L)
+    debug(s"Testing that $hash = 4004383623972821843L")
+    assert(hash == 4004383623972821843L)
   }
   
   test("DHash Of Large, Medium, And Small Sample 1 Must Be Similar") {