From 417f8bb74cecca7e27a10fd85f0e657177dfce88 Mon Sep 17 00:00:00 2001
From: Ben Ubois <ben@benubois.com>
Date: Wed, 28 Nov 2012 00:07:42 -0800
Subject: [PATCH 1/3] Added an example of a custom filter.

---
 README.md | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/README.md b/README.md
index 113706c3..28690d06 100644
--- a/README.md
+++ b/README.md
@@ -151,6 +151,36 @@ EmojiPipeline = Pipeline.new [
 ], context, {}
 ```
 
+## Extending
+If you need a custom filter, you can write your own. All that is needed is a
+class that inherits from `HTML::Pipeline::Filter` and has a `call` method. For
+example this filter adds a base url to images that are root relative:
+
+```ruby
+require 'uri'
+
+class RootRelativeFilter < HTML::Pipeline::Filter
+
+  def call
+    doc.search("img").each do |img| 
+      next if img['src'].nil?
+      src = img['src'].strip
+      if src.start_with? '/'
+        img["src"] = URI.join(context[:base_url], src).to_s
+      end
+    end
+    doc
+  end
+
+end
+```
+
+Now this filter can be used in a pipeline:
+
+```ruby
+Pipeline.new [ ImageSourceFilter ], { :base_url => 'http://somehost.com' }
+```
+
 ## Development
 
 To see what has changed in recent versions, see the [CHANGELOG](https://github.com/jch/html-pipeline/blob/master/CHANGELOG.md).

From 55560db7feb2cc53a21e3432e8916f148972e831 Mon Sep 17 00:00:00 2001
From: Ben Ubois <ben@benubois.com>
Date: Wed, 28 Nov 2012 00:11:08 -0800
Subject: [PATCH 2/3] Fixed typo in example.

---
 README.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/README.md b/README.md
index 28690d06..590469ad 100644
--- a/README.md
+++ b/README.md
@@ -178,7 +178,7 @@ end
 Now this filter can be used in a pipeline:
 
 ```ruby
-Pipeline.new [ ImageSourceFilter ], { :base_url => 'http://somehost.com' }
+Pipeline.new [ RootRelativeFilter ], { :base_url => 'http://somehost.com' }
 ```
 
 ## Development

From 2d8b046f652b2e0fd54e30483f028718ff7b0a28 Mon Sep 17 00:00:00 2001
From: Ben Ubois <ben@benubois.com>
Date: Wed, 28 Nov 2012 01:09:50 -0800
Subject: [PATCH 3/3] Extending example copy edits.

---
 README.md | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/README.md b/README.md
index 590469ad..f86f6786 100644
--- a/README.md
+++ b/README.md
@@ -152,9 +152,10 @@ EmojiPipeline = Pipeline.new [
 ```
 
 ## Extending
-If you need a custom filter, you can write your own. All that is needed is a
-class that inherits from `HTML::Pipeline::Filter` and has a `call` method. For
-example this filter adds a base url to images that are root relative:
+To write a custom filter, you need a class with a `call` method that inherits
+from `HTML::Pipeline::Filter`.
+
+For example this filter adds a base url to images that are root relative:
 
 ```ruby
 require 'uri'