changed overlay_watermark() to check for an alpha value before applying the image to help support PNG-24s with alpha transparency
http://codeigniter.com/bug_tracker/bug/4506/
diff --git a/user_guide/changelog.html b/user_guide/changelog.html
index c523165..43905db 100644
--- a/user_guide/changelog.html
+++ b/user_guide/changelog.html
@@ -139,7 +139,8 @@
<li>Fixed a bug in the table library that could cause identically constructed rows to be dropped (#3459).</li>
<li>Fixed a bug (#4206) in the Directory Helper where the directory resource was not being closed, and minor improvements.</li>
<li>Fixed a bug where SMTP emails were not having dot transformation performed on lines that begin with a dot.</li>
- <li>Fixed a bug in display_error() in the DB driver that was instantiating new Language and Exception objects, and not using the error heading.</li>
+ <li>Fixed a bug in display_error() in the DB driver that was instantiating new Language and Exception objects, and not using the error heading.</li>
+ <li>Fixed a bug (#4506) with overlay_watermark() in the Image library preventing support for PNG-24s with alpha transparency</li>
</ul>
<h2>Version 1.6.1</h2>