ChrisHurst

MyWebsiteAdvisor

This plugin allows you to watermark your previously uploaded images using a PNG image file with transparency as well as text signature. 
The user friendly settings page allows for control over the appearance of your watermark. 
You can set your watermarks to always be a specific percentage of the target image. 
This plugin will add the watermarks to ALL of the images in your WordPress uploads directory.
Please BACK UP all of your uploads via FTP before using this plugin!
<a href="http://mywebsiteadvisor.com/plugins/bulk-watermark/" rel="nofollow ugc">Upgrade to Bulk Watermark Ultra</a> for advanced 
watermark features including:
<ul>
<li>Fully Adjustable Text and Image Watermark Positions</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>
Check out the <a href="http://www.youtube.com/watch?v=XkFXBjfzw2I&hd=1" rel="nofollow ugc">Bulk Watermark Plugin for WordPress Video Tutorial</a>:
<iframe loading="lazy" title="Bulk Watermark for WordPress Tutorial" width="750" height="422" src="https://www.youtube.com/embed/XkFXBjfzw2I?feature=oembed" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" referrerpolicy="strict-origin-when-cross-origin" allowfullscreen></iframe>
Developer Website: http://MyWebsiteAdvisor.com/
Plugin Support: http://MyWebsiteAdvisor.com/support/
Plugin Page: http://mywebsiteadvisor.com/plugins/bulk-watermark/
Compare Watermark Plugins: http://MyWebsiteAdvisor.com/tools/wordpress-plugins/watermark-plugins-for-wordpress/
Video Tutorial: http://mywebsiteadvisor.com/learning/video-tutorials/bulk-watermark-tutorial/
Requirements:
<ul>
<li>PHP v5.0+</li>
<li>WordPress v3.3+</li>
<li>GD extension for PHP</li>
<li>FreeType extension for PHP</li>
</ul>
To-do:

Bulk Watermark

Adds an image and/or text watermark to all uploaded images, using PNG images with transparency.

BeRocket

Dmytro Holovnia

Product Watermark for WooCommerce plugin allows you to add watermark to images that applied to products. These watermarks can be an image copyright symbol, company logo or text. You will need few clicks to apply a logo or a watermark on all your product images.
<h4>Features:</h4>
✅ Watermark for product images 
✅ Custom watermark position 
✅ Watermarks with transparency is supported 
✅ Custom CSS for front end pages
<h4>Additional Features in Paid Plugin:</h4>
✅ Custom watermark size 
✅ Different watermarks for different image type 
✅ Save aspect ratio for watermarks 
✅ From 1 to 5 watermarks 
✅ Place text to images 
✅ Options to set text color, size and transparency
<h4>Plugin Links:</h4>
<a href="https://berocket.com/woocommerce-products-image-watermark/?utm_source=wordpress_org&utm_medium=plugin_links&utm_campaign=image_watermark" rel="nofollow ugc">Paid Plugin</a> 
<a href="https://woocommerce-currency-exchange.berocket.com/shop/?utm_source=wordpress_org&utm_medium=plugin_links&utm_campaign=image_watermark" rel="nofollow ugc">Demo</a> 
<a href="https://docs.berocket.com/plugin/woocommerce-products-image-watermark?utm_source=wordpress_org&utm_medium=plugin_links&utm_campaign=image_watermark" rel="nofollow ugc">Docs</a>
<h4>🍬 Wanna try admin side?</h4>
<a href="https://berocket.com/woocommerce-products-image-watermark/?utm_source=wordpress_org&utm_medium=admin_demo&utm_campaign=image_watermark#try-admin" rel="nofollow ugc">Admin Demo</a> – Get access to this plugin’s admin and try it from inside. Change things and watch how they work.
<h4>Premium plugin video</h4>
<iframe loading="lazy" class="youtube-player" width="750" height="422" src="https://www.youtube.com/embed/SrIhU35n0P0?version=3&rel=1&showsearch=0&showinfo=1&iv_load_policy=1&fs=1&hl=en-US&autohide=2&wmode=transparent" allowfullscreen="true" style="border:0;" sandbox="allow-scripts allow-same-origin allow-popups allow-presentation allow-popups-to-escape-sandbox"></iframe> 
we don’t have video with free plugin right now but we are working on it
<h4>Compatibility with WooCommerce plugins</h4>
Product Watermark for WooCommerce has been tested and compatibility is certain with the following WooCommerce plugins that you can add to your site:
🔸 <a href="https://wordpress.org/plugins/woocommerce-ajax-filters/" rel="ugc">Advanced AJAX Product Filters</a> 
🔸 <a href="https://wordpress.org/plugins/load-more-products-for-woocommerce/" rel="ugc">Load More Products for WooCommerce</a> 
🔸 <a href="https://wordpress.org/plugins/gridlist-view-for-woocommerce/" rel="ugc">Grid/List View for WooCommerce</a> 
🔸 <a href="https://wordpress.org/plugins/product-preview-for-woocommerce/" rel="ugc">Product Preview for WooCommerce</a> 
🔸 <a href="https://wordpress.org/plugins/products-compare-for-woocommerce/" rel="ugc">Products Compare for WooCommerce</a> 
🔸 <a href="https://wordpress.org/plugins/sales-report-for-woocommerce/" rel="ugc">Sales Report for WooCommerce</a> 
🔸 <a href="https://wordpress.org/plugins/wish-wait-list-for-woocommerce/" rel="ugc">Wishlist and Waitlist for WooCommerce</a>

Product Watermark for WooCommerce

Yes, it worked perfectly on my client's website. Thank you so much guys!

This plugin really works!

Allows you to add watermark to images that applied to products

Bulk Watermark vs Product Watermark for WooCommerce