eaxjp

Image will be shrink in the case of automatic JPEG and PNG format to upload the image. 
There are the following features in isShrinker WordPress Plugin.
Can specify the maximum file size. 
Keep aspect ratio. 
Convert image inclination from inclination information of image
If you upload, such as iPhone app slope of image because reduced after correction 
it appears in the blog exactly as it appears in the iPhone.
The maximum file size of the image is 50KB by default 
Length of the long side of the image is 640px by default 
And it is with, but you can change from the management screen of WordPress.
Upload png image ‘watermark.png’ to plugin directory and then watermark will be enable. 
Watermark add on right bottom of image. 
If watermark enabled water mark transparency setting is enable.
<h3>Arbitrary section 1</h3>

isShrinker

When uploading, it will shrink the image automatically. The feature is  keeping the aspect ratio and  maximum file size can be specified.

dFactory

<a href="http://www.dfactory.co/products/image-watermark/" rel="nofollow ugc">Image Watermark</a> allows you to automatically watermark images uploaded to the WordPress Media Library and bulk watermark previously uploaded images.
For more information, check out plugin page at <a href="http://www.dfactory.co/" rel="nofollow ugc">dFactory</a>, <a href="http://www.dfactory.co/docs/image-watermark/" rel="nofollow ugc">documentation page</a> or plugin <a href="http://www.dfactory.co/support/forum/image-watermark/" rel="nofollow ugc">support forum</a>.
<h4>Features include:</h4>
<ul>
<li>Bulk watermark – Apply watermark option in Media Library actions</li>
<li>Watermark images already uploaded to Media Library</li>
<li>GD LIbrary and ImageMagic support</li>
<li>Image backup functionality</li>
<li>Option to remove watermark</li>
<li>Flexible watermark position</li>
<li>Watermark image preview</li>
<li>Set watermark offset</li>
<li>Select post types where watermark will be aplied to uploaded images or select adding watermark during any image upload</li>
<li>Select from 3 methods of aplying watermark size: original, custom or scaled</li>
<li>Set watermark transparency / opacity</li>
<li>Select image format (baseline or progressive)</li>
<li>Set image quality</li>
<li>Protect your images from copying via drag&drop</li>
<li>Disable right mouse click on images</li>
<li>Disable image protection for logged-in users</li>
<li>.pot file for translations included</li>
</ul>

Image Watermark

Image Watermark allows you to automatically watermark images uploaded to the WordPress Media Library and bulk watermark previously uploaded images.

isShrinker vs Image Watermark