Michael Zangl

This plugin allows you to add a watermark images on all images that were uploaded in your wordpress. The watermark is generated on-the-fly and cached for faster access.
To see the plugin in action, select “Add watermark to all images”, chose a watermark image and and submit the settings page. You should then see the watermark appearing on your site. You might need to reload the page (F5 in most browsers) to bypass the browser cache.
The plugin does not change your source images. To disable all watermarks, simply disable the plugin, and everything is back to normal.
If you encounter errors (especially syntax errors), check your PHP version. It should be at least 7.0. This plugin requires Apache and mod_rewrite.

Add Watermarks

Adds watermarks to selected images without changing the original image.

sverde1

This plugin allows you to watermark your uploaded images. You can create watermark with different fonts, colors and 
apply those watermarks to different image sizes (thumbnail, medium, large, fullsize). You can also position the watermark 
anywhere on the image within Watermark RELOADED settings. Watermarking settings are simple to use and provide you with 
instant preview of how your watermark will look like on the uploaded image.
<a href="http://eappz.eu/en/products/watermark-reloaded-pro/" rel="nofollow ugc">Upgrade to Watermark RELOADED Pro</a> for more 
watermarking features:
<ul>
<li>watermark opacity</li>
<li>image watermark</li>
<li>watermark background color</li>
<li>text watermark with outline</li>
<li>text watermark with variables</li>
<li>upload time option to turn off the watermarking</li>
<li>many more amazing features</li>
</ul>
Requirements:
<ul>
<li>PHP5</li>
<li>GD extension for PHP</li>
<li>FreeType Library</li>
</ul>
To-do:
<ul>
<li>Watermark RELOADED Bug fixing (request by: all)</li>
<li>Don’t display watermark on images where watermark would overflow image (request by: alex)</li>
<li>Watermark aditional image sizes added by other plugins (request by: twincascos)</li>
<li>Watermark images that were uploaded before plugin was installed (request by: anchy-9, Blogging Junction, Ashkir, Mobile Ground, Nicolas)</li>
<li>Image size aware watermark (request by: brohism)</li>
<li>Watermark outside picture</li>
</ul>

Watermark RELOADED

Add watermark to your uploaded images and customize your watermark appearance on a user friendly settings page.

Add Watermarks vs Watermark RELOADED