3 files changed, 40 insertions, 4 deletions
diff --git a/actionpack/CHANGELOG.md b/actionpack/CHANGELOG.md
index d6a2687037..3c62d39e07 100644
--- a/actionpack/CHANGELOG.md
+++ b/actionpack/CHANGELOG.md
@@ -1,5 +1,26 @@
 ## Rails 4.0.0 (unreleased) ##
 
+*   Fix `image_alt` method to work with underscored or hyphenated file names.
+    Currently, underscored filenames become 
+    `<img alt="A_long_file_name_with_underscores"` in HTML, which is 
+    poor for accessibility; Apple's VoiceOver Utility pronounces
+    each underscore. "A_long_file_name" thus becomes "A underscore 
+    long underscore file underscore name." This patch makes underscored 
+    or hyphenated file names (both of which are very popular naming
+    conventions) read more naturally in screen readers by converting
+    both hyphens and underscores to spaces.
+
+    Example:
+        # current implementation
+        image_tag('underscored_file_name.png') 
+        #=> <img alt="Underscored_file_name" src="/assets/underscored_file_name.png" />
+
+        # this patch
+        image_tag('underscored_file_name.png')
+        #=> <img alt="Underscored file name" src="/assets/underscored_file_name.png" />
+
+    *Nick Cox*
+
 *   We don't support the `:controller` option for route definitions
     with the ruby constant notation. This will now result in an
     `ArgumentError`.
diff --git a/actionpack/lib/action_view/helpers/asset_tag_helper.rb b/actionpack/lib/action_view/helpers/asset_tag_helper.rb
index 5b3a2cae7c..6387b89a81 100644
--- a/actionpack/lib/action_view/helpers/asset_tag_helper.rb
+++ b/actionpack/lib/action_view/helpers/asset_tag_helper.rb
@@ -214,10 +214,24 @@ module ActionView
       end
 
       # Returns a string suitable for an html image tag alt attribute.
-      # +src+ is meant to be an image file path.
-      # It removes the basename of the file path and the digest, if any.
+      # The +src+ argument is meant to be an image file path.
+      # The method removes the basename of the file path and the digest, 
+      # if any. It also removes hyphens and underscores from file names and
+      # replaces them with spaces, returning a space-separated, titleized
+      # string.
+      # 
+      # ==== Examples
+      #
+      #   image_tag('rails.png')
+      #   # => <img alt="Rails" src="/assets/rails.png" />
+      #
+      #   image_tag('hyphenated-file-name.png')
+      #   # => <img alt="Hyphenated file name" src="/assets/hyphenated-file-name.png" />
+      #   
+      #   image_tag('underscored_file_name.png')
+      #   # => <img alt="Underscored file name" src="/assets/underscored_file_name.png" />
       def image_alt(src)
-        File.basename(src, '.*').sub(/-[[:xdigit:]]{32}\z/, '').capitalize
+        File.basename(src, '.*').sub(/-[[:xdigit:]]{32}\z/, '').tr('-_', ' ').capitalize
       end
 
       # Returns an html video tag for the +sources+. If +sources+ is a string,
diff --git a/actionpack/test/template/asset_tag_helper_test.rb b/actionpack/test/template/asset_tag_helper_test.rb
index 82c9d383ac..11614a45dc 100644
--- a/actionpack/test/template/asset_tag_helper_test.rb
+++ b/actionpack/test/template/asset_tag_helper_test.rb
@@ -443,7 +443,8 @@ class AssetTagHelperTest < ActionView::TestCase
     [nil, '/', '/foo/bar/', 'foo/bar/'].each do |prefix|
       assert_equal 'Rails', image_alt("#{prefix}rails.png")
       assert_equal 'Rails', image_alt("#{prefix}rails-9c0a079bdd7701d7e729bd956823d153.png")
-      assert_equal 'Avatar-0000', image_alt("#{prefix}avatar-0000.png")
+      assert_equal 'Long file name with hyphens', image_alt("#{prefix}long-file-name-with-hyphens.png") 
+      assert_equal 'Long file name with underscores', image_alt("#{prefix}long_file_name_with_underscores.png")  
     end
   end