Kiminori Shimada - ?? ??

You will be able to resize smartphone, tablet PC for the image in the article. This Plugin is the ideal tool for Responsive Web design.
<h3>Plug-in Usage</h3>
In order to use this plug-in, there is no special knowledge. 
enable the plug-in, will start running.
If necessary, from the configuration screen, you can also specify the width of each device.

Auto Image Resize

jegbagus

This plugin have ability to override default worpdress behavior and disable croping image but try to resize image to fit rectangle container size and fill space with background color. 
You also able to choose background color to use.
Links: <a href="http://farm9.staticflickr.com/8459/8016053956_8616f8b1f8_z.jpg" rel="nofollow ugc">Example</a> | <a href="http://jegtheme.com" rel="nofollow ugc">Author Homepage</a>

JResizr

Resize with no crop and fill background color of the rest area

Auto Image Resize vs JResizr