mryuanshu

WppaoImage图片增强插件，来自Wppao团队缘殊开发，只为完成网站运营时必须要的几个图片处理功能，如远程图片本地化，图片加水印等功能。
目前支持的功能： 
* 图片文字水印功能 
* 图片文字水印字体自选 
* 图片文字水印尺寸自选 
* 图片文字水印颜色自选 
* 图片使用图片水印功能 
* 水印位置自选

Wppao Image

Wordpress图片增强插件，可以将远程图片获取到本地，并且可以对文章的图片打水印。

ChrisHurst

MyWebsiteAdvisor

This plugin allows you to Automatically displays a watermark on images which have been hotlinked as they are viewed on the Hotlinkers Website. 
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. 
Watermarks are non-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!
<a href="http://MyWebsiteAdvisor.com/tools/wordpress-plugins/watermark-hotlink-protection/" rel="nofollow ugc">Upgrade to Watermark Hotlink Protection Ultra</a> for advanced 
watermark features including:
<ul>
<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/watermark-hotlink-protection/
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:

Watermark Hotlink Protection

Displays a watermark on images which have been hotlinked

Wppao Image vs Watermark Hotlink Protection