ChrisHurst

MyWebsiteAdvisor

This plugin allows you to Automatically add a watermark to all images as they are viewed on your WordPress Website. 
Watermarks are not permenant, original images are not edited. 
The plugin maintains a cached copy of the watermarked image, which can be cleared and regenerated at any time!
The plugin uses PNG watermark images with transparency for precise control over the appearance of the watermarks. 
This plugin also supports simple text watermarks with adjustable color, size and transparency. 
The user friendly settings page allows for control over the appearance of your watermark. 
The watermark preview feature allows for easy testing of the plugin settings. 
The watermark size is controlled as a percentage of the target image, 50% means the watermark will be half the width of the target image.
This plugin needs to add to your .htaccess file, and will not work if you do not have a .htaccess file or mod_rewrite.
NOTE: 
This plugin may have a slight impact on the performance of your web server, use of the Included Basic Caching System is Highly Recommended! 
The premium version of this plugin also includes an Advanced Cache System which performs nearly identical to when the plugin is disabled.
<a href="http://MyWebsiteAdvisor.com/tools/wordpress-plugins/simple-watermark/" rel="nofollow ugc">Upgrade to Simple Watermark Ultra</a> for advanced 
watermark features including:
<ul>
<li>Improved Performance with Advanced Cache</li>
<li>Fully Adjustable Image Watermark Position</li>
<li>Fully Adjustable Text Watermark Position</li>
<li>Adjustable JPEG Image Output Quality</li>
<li>Highest Quality Watermarks using Image Re-sampling rather than Re-sizing</li>
<li>Lifetime Priority Support and Update License</li>
</ul>
Developer Website: http://MyWebsiteAdvisor.com/
Plugin Support: http://MyWebsiteAdvisor.com/support/
Plugin Page: http://MyWebsiteAdvisor.com/tools/wordpress-plugins/simple-watermark/
Requirements:
<ul>
<li>PHP v5.0+</li>
<li>WordPress v3.3+</li>
<li>GD extension for PHP</li>
<li>FreeType extension for PHP</li>
<li>.htaccess file and mod_rewrite</li>
</ul>
To-do:

Simple Watermark

Automatically watermark images as they are viewed

Protect Uploads

The uploads directory is where the files of the WordPress library are stored. Unfortunelty, this directory is not protected. A person who wants to see all your library could list it instantly going to : http://yourwebsite/wp-content/uploads . This plugin will hide the content by adding an index.php file on the root of your uploads directory or by setting an htaccess which will return a 403 error (Forbidden Access).
<ul>
<li>Depending on your server setting, the htaccess option could be disabled.</li>
</ul>
New Features in Version 0.6.0:
<ul>
<li>Image Watermarking: Add text watermarks to your uploaded images with customizable position, opacity, and font size.</li>
<li>Right-Click Protection: Prevent users from right-clicking to download or save your images.</li>
<li>Password Protection: Secure individual media files with passwords. Multiple passwords can be set for each file with custom labels.</li>
<li>Access Logging: Track who accesses your password-protected files with detailed logs including IP address and user agent.</li>
</ul>
Available languages:
<ul>
<li>English</li>
<li>Français</li>
<li>Español</li>
<li>Italian (thanks to Marko97)</li>
</ul>

Do not download. The plugin has been changed not too long ago and it now infects your wordpress installation, and possible spreads itself to other sites if you are on shared hosting.

It's a virus

Protect your uploads directory. Prevent browsing, add watermarks, disable right-click, and password-protect files. For more information, visit protect …

Simple Watermark vs Protect Uploads