wework4web

With the help of the shortcode, this plugin helps you to resize your image in different size. You never need to update your thumbnail size settings and re-upload all the image as you used to do before. It gives you the unlimited limitation for image resize.
How To Use
[image-resize width=100 height=100 ref=w default=your_default_image.png]
Parameters: 
width: (required) Width of the image in px
height: (required) Height of the image in px
Ref: (optional) w if you want the width reference, h for height reference. No ref parameter means you will have image with maintained ratio.
default: (optional) Your default image path. The default image is shown when you don’t have featured image in your post.
You can use the shortcode in your post,page content area.
For using in templates, you can use the wordpress do_shortcode function. Like:
<?php do_shortcode(‘[image-resize width=100 height=100 ref=w default=your_default_image.png]’); ?>
While using in templates, it must be inside the post loop.
If you have any queries do write in the support section.

Image Resizer On The Fly

This plugin resize featured image on the fly and gives u ability to remove automatically resized image from admin.

dmry

This plugin enables you to automatically resize every user-posted image which is larger than given dimensions. Original plugin writen by <a href="http://www.ncode.nl/vbulletinplugins/" rel="nofollow ugc">Jorrit Schippers</a> for vBulletin.
Some features:
<ul>
<li>No resizing</li>
<li>Enlargement in the same document</li>
<li>Enlargement in the same window</li>
<li>Enlargement in a new window</li>
<li>Enlargement in modal window</li>
<li>Any JavaScript Framework is not required</li>
</ul>
It also adds an information bar (which is not displayed when the image is too small) giving information about the original dimensions and filesize.
Localization:
<ul>
<li>Belorussian (be_BY) – <a href="http://www.fatcow.com/" rel="nofollow ugc">FatCow</a></li>
<li>Arabic (ar_AR) – <a href="http://linuxawi.com/" rel="nofollow ugc">ZAH3R</a></li>
<li>Japanese (ja) – <a href="http://blog.osakana.net/" rel="nofollow ugc">osakanataro</a></li>
</ul>

nCode Image Resizer

This plugin enables you to automatically resize every user-posted image which is larger than given dimensions.

Image Resizer On The Fly vs nCode Image Resizer