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Header Watermark provides you with extra flexibility and control over the header image(s) for your WordPress site:
<ul>
<li>Use any image from your Media Library as a watermark for your header image(s)</li>
<li>Control the placement and opacity of the watermark</li>
<li>Select any suitable image from your Media Library as your header image(s)</li>
<li>Control which images are used for random header images</li>
</ul>
<h3>Requirements</h3>
Header Watermark requires the following to work:
<ul>
<li>GD Library PHP extension – version 2.0.28 or higher</li>
<li>The WordPress theme must use the get_header_image() function to generate the header image and must also define the HEADER_IMAGE_WIDTH and HEADER_IMAGE_HEIGHT constants</li>
</ul>
<h3>Themes</h3>
This plugin works with the Twenty Ten theme with no further configuration.
If you use this plugin with the Twenty Eleven theme, you may see a notice at the top of your website/WordPress admin pages like this:
<blockquote>
Notice: Constant HEADER_IMAGE already defined in /var/www/yoursite/wordpress/wp-content/themes/twentyeleven/functions.php on line 118
</blockquote>
You may also find that you get occasional errors on some WordPress admin pages, for example if you activate a different theme.
To prevent the notice and errors, find and change the following line in the functions.php file of the Twenty Eleven theme:
Change this: 
 define( ‘HEADER_IMAGE’, ” ); 
to this: 
 if ( ! defined( ‘HEADER_IMAGE’ ) ) { 
 define( ‘HEADER_IMAGE’, ” ); 
 }
Any other themes that define the HEADER_IMAGE constant may have the same problems and need to be altered in the same way for the plugin to work.

Header Watermark

Add a watermark image to your WordPress header image and use suitable images from your media library as the header image(s).

dFactory

<a href="http://www.dfactory.co/products/image-watermark/" rel="nofollow ugc">Image Watermark</a> allows you to automatically watermark images uploaded to the WordPress Media Library and bulk watermark previously uploaded images.
For more information, check out plugin page at <a href="http://www.dfactory.co/" rel="nofollow ugc">dFactory</a>, <a href="http://www.dfactory.co/docs/image-watermark/" rel="nofollow ugc">documentation page</a> or plugin <a href="http://www.dfactory.co/support/forum/image-watermark/" rel="nofollow ugc">support forum</a>.
<h4>Features include:</h4>
<ul>
<li>Bulk watermark – Apply watermark option in Media Library actions</li>
<li>Watermark images already uploaded to Media Library</li>
<li>GD LIbrary and ImageMagic support</li>
<li>Image backup functionality</li>
<li>Option to remove watermark</li>
<li>Flexible watermark position</li>
<li>Watermark image preview</li>
<li>Set watermark offset</li>
<li>Select post types where watermark will be aplied to uploaded images or select adding watermark during any image upload</li>
<li>Select from 3 methods of aplying watermark size: original, custom or scaled</li>
<li>Set watermark transparency / opacity</li>
<li>Select image format (baseline or progressive)</li>
<li>Set image quality</li>
<li>Protect your images from copying via drag&drop</li>
<li>Disable right mouse click on images</li>
<li>Disable image protection for logged-in users</li>
<li>.pot file for translations included</li>
</ul>

Image Watermark

Image Watermark allows you to automatically watermark images uploaded to the WordPress Media Library and bulk watermark previously uploaded images.

Header Watermark vs Image Watermark