keighl

Organize “before and after” style portfolios embedded within WordPress posts. Before/After allows you to select specific images out of your media library, and sort them into respective before and after groups from the post editing page. Useful for anyone who features their work or services (web-designers, artists, plumbers, etc.) on their site.
<a href="http://www.keighl.com/plugins/before-after/" rel="nofollow ugc">Support & Examples</a>
=Use=
<ul>
<li>Add images to your Media Library; these images will become available to you on the post add/edit page.</li>
<li>On the post add/edit page, simply drag images from the Media Library column into the Before and After columns.</li>
<li>To remove an item, double-click it.</li>
</ul>
=Template Tags=
=<code><?php $beforeafter->is_gallery( id ); ?></code>=
Returns true if there is a Before/After gallery associated with a particular post.
<ul>
<li>id:
<ul>
<li>A post id. Typically the current post, $post->ID</li>
</ul>
</li>
</ul>
=<code><?php $beforeafter->gallery( type , id , file , links , list , rel , limit ); ?></code>=
Returns the images stored in a particular Before/After gallery.
<ul>
<li>
type:
<ul>
<li>Determines which gallery to return: before or after.</li>
<li>Values: ‘before’ , ‘after’</li>
<li>Default: ‘after’</li>
</ul>
</li>
<li>
id:
<ul>
<li>The post id. If set to 0, will return images from all posts with Before/After galleries.</li>
<li>Default: 0</li>
</ul>
</li>
<li>
file:
<ul>
<li>Determines the type of image to return: the original image file, or the thumbnail.</li>
<li>Values: ‘thumb’ , ‘file’</li>
<li>Default: ‘thumb’</li>
</ul>
</li>
<li>
links:
<ul>
<li>If set to true, will wrap images with links to the original files.</li>
<li>Values: true, false</li>
<li>Default: true</li>
</ul>
</li>
<li>
list:
<ul>
<li>If set to true, wraps the image in </li>
<li> tags.</li>
<li>Values: true, fase</li>
<li>Default: false</li>
</ul>
</li>
<li>
rel:
<ul>
<li>Alters the default rel parameter for image links.</li>
<li>Default: ‘beforeafter’</li>
</ul>
</li>
<li>
limit:
<ul>
<li>Limits how many items are returned.</li>
<li>Default: all of ’em.</li>
</ul>
</li>
</ul>

Before/After

A "before and after" portfolio generator. Uses images uploaded to the media library; organize galleries from the post add/edit page.

Aluka

BA Plus – Before & After Image Slider is a plugin for WordPress which allow you compare two or more different images in the same frame.
<a href="http://dev.abydx.com/bai/" title="Live Demo" rel="nofollow ugc">Try out the demo</a> to see it in action!
<h3>Features</h3>
<ul>
<li>Compare two or more images</li>
<li>Slideshow Option</li>
<li>Auto Slide Bar Mode</li>
<li>Option to change slide duration</li>
<li>Fully Responsive</li>
<li>Touch & Swipe on Mobile Devices</li>
<li>Define Any Initial Position for Your Slider</li>
<li>Horizontal or Vertical</li>
<li>Hover or Drag Interaction</li>
<li>Many Styles to Choose</li>
<li>Many Options to Customize (Labels, Captions, Slide Bar,…)</li>
<li>Shortcode Generator</li>
</ul>
<h3>Premium Features</h3>
<ul>
<li>Import/Export Customizer Settings</li>
<li>Export Slider to Static HTML</li>
</ul>
<h3>Premium Support</h3>
We provides very limited support on the WordPress.org forums. Please feel free to post questions or bug reports, but for timely support, we recommend purchasing Pro version. 
<a href="http://dev.abydx.com/bai/pro/" title="Pro version" rel="nofollow ugc">View pro version</a>
<h3>Privacy Policy</h3>
This plugin doesn’t collect/store any user related information.

BA Plus – Before & After Image Slider FREE

This plugin works as advertised, and I will end up getting the premium version as it is reasonably priced.

Excellent

Offers a simple and effective way to compare two or more different images in the same frame.

Before/After vs BA Plus – Before & After Image Slider FREE