fix issue #28: dhash should compute horizontally. Version bump to 3.0

README.rst

@@ -40,4 +40,15 @@ Source hosted at github: https://github.com/JohannesBuchner/imagehash
 .. _wHash: https://fullstackml.com/2016/07/02/wavelet-image-hash-in-python/
 .. _pypi: https://pypi.python.org/pypi/ImageHash
 
+Changelog
+----------
+
+* 3.0: dhash had a bug: It computed pixel differences vertically, not horizontally.
+       I modified it to follow `dHash`_. The old function is available as dhash_vertical.
+
+* 2.0: added whash
+
+* 1.0: initial ahash, dhash, phash implementations.
+
+
 

imagehash/__init__.py

@@ -154,6 +154,24 @@ def dhash(image, hash_size=8):
 	Difference Hash computation.
 
 	following http://www.hackerfactor.com/blog/index.php?/archives/529-Kind-of-Like-That.html
+	
+	computes differences horizontally
+
+	@image must be a PIL instance.
+	"""
+	image = image.convert("L").resize((hash_size, hash_size + 1), Image.ANTIALIAS)
+	pixels = numpy.array(image.getdata(), dtype=numpy.float).reshape((hash_size + 1, hash_size))
+	# compute differences
+	diff = pixels[:, 1:] > pixels[:, :-1]
+	return ImageHash(diff)
+
+def dhash_vertical(image, hash_size=8):
+	"""
+	Difference Hash computation.
+
+	following http://www.hackerfactor.com/blog/index.php?/archives/529-Kind-of-Like-That.html
+
+	computes differences vertically
 
 	@image must be a PIL instance.
 	"""

setup.py

@@ -9,7 +9,7 @@
 
 setup(
     name='ImageHash',
-    version='2.2',
+    version='3.0',
     author='Johannes Buchner',
     author_email='[email protected]',
     packages=['imagehash'],