Makoto

This plugin allows you and your visitors to add comment as textual annotations to images by select a region of the image and then attach a textual description, the concept of annotating images with user comments. 
The text is intergrated with WordPress comment system. 
Integration with <a href="http://www.flipbit.co.uk/jquery-image-annotation.html" rel="nofollow ugc">JQuery Image Annotation from Chris</a> with <a href="http://github.com/stas/jquery-image-annotate-php-fork" rel="nofollow ugc">PHP support from GitHub</a>. 
Modified from <a href="http://www.superwhite.cc/demon/image-annotation-plugin" rel="nofollow ugc">Demon Image Annotation version 1.0</a>. 
Icons from <a href="http://www.famfamfam.com/lab/icons/silk/" rel="nofollow ugc">Fam Fam Fam</a>
Features:
<ol>
<li>Ability to add notes to your uploaded pictures.</li>
<li>Show notes on single page, front page, archive page and etc.</li>
<li>Notes synced with WordPress commenting system but there’s option to turn it off.</li>
<li>Gravatar in the notes.</li>
<li>Commentator’s name in the notes.</li>
<li>Image thumbnail appear at comment area, but there’s option to turn it off.</li>
<li>No hard coding required.</li>
<li>Admin page.</li>
<li>Remove all database if you wish to not using the plugin anymore.</li>
</ol>

Guan Image Notes

Image tagging system sync with WordPress comment system. Or also known as image notes, or image annotation.

durgathakur

This plugin allows you to add textual annotations to images by select a region of the image and then attach a textual description, the concept of annotating images with user comments. Integration with JQuery Image Annotation from Chris (http://www.flipbit.co.uk/jquery-image-annotation.html) with PHP support from GitHub (http://github.com/stas/jquery-image-annotate-php-fork).
Some features:
<ul>
<li>Admin page</li>
<li>Option to approve, edit amd remove image notes in admin page.</li>
<li>Auto insert unique id attribute for all the images for image note.</li>
<li>Show notes on other pages such as home and archive.</li>
<li>Gravatar in the notes</li>
<li>Option to sync with wordpress comments.</li>
<li>Option to show thumbnail in comment list.</li>
<li>Option to include post id in every auto insert images id.</li>
<li>‘Mouseover to load notes’ on top of every image note (editable).</li>
<li>‘Link’ on top of every image note if hyperlink image (editable).</li>
</ul>

wp image annotation

Allows you to add textual annotations to images by select a region of the image and then attach a textual description.

Guan Image Notes vs wp image annotation