HETWORKS

You probably know that the speed of your website is important for both user experience and for your search engine ranking. The people 
at TinyPNG.com offered this great service where you could upload your PNG images and shortly also your JPG images, to have the file size 
shrinked to much lower amount of data, without a noticable reduce of image quality. And that is great! Compare your Google pagespeed score 
before and after you shrinked your images. You will gain many points.
The disadvantage of using TinyPNG is that you had to use the service upfront, before you could upload your images into your WordPress 
medialibrary you had to upload them to TinyPNG and download the shrinked files again. When the images were already in your medialibrary you 
had to do this all over, also for the images that were cropped by WordPress into the different filesizes. With this plugin that is all history. 
You just upload your images and as part of the proces these images are processed by TinyPNG.
This is what TinyPNG say themselves: 
How does it work? TinyPNG uses smart lossy compression techniques to reduce the file size of your PNG files. By selectively decreasing the 
number of colors in the image, fewer bytes are required to store the data. The effect is nearly invisible but it makes a very large 
difference in file size!

WordPress Image shrinker

Reduce image file sizes drastically and improve performance and Pagespeed score using the TinyPNG API within WordPress. Works for both PNGs and JPGs.

Takis Bouyouris

<h4>Deliver downsized images to mobile devices</h4>
WURFL Image Tailor (WIT) http://web.wurfl.io/#wit is an automatic image transformation and delivery service, based on 
the WURFL device detection library http://web.wurfl.io/#learnmore. WURFL will detect the device, and its screen size 
and it will resize and optimize (downsize) each image accordingly.
This plugin hooks automatically into the WordPress HTML image code generation process and changes each image’s src 
attribute, so that it is optimized for that specific device and delivered via the WURFL Image Tailor service.
The plugin also filters the post contents to replace the src attribute of images in it. But it currently does this for 
all (!) images that it finds in the post contents. Right now it does not replace the href attribute of links that 
point to images in the media gallery.
<h4>Use WordPress functions and filters</h4>
Make sure you use functions like:
<ul>
<li><code>the_post_thumbnail(</code>…<code>)</code></li>
<li><code>wp_get_attachment_image(</code>…<code>)</code></li>
<li><code>the_content(</code>…<code>)</code></li>
</ul>
However, do not use <code>wp_get_attachment_image_src()</code>, because we cannot hook into it (yet)! Right now the plugin hooks 
into these WordPress filters:
<ul>
<li><code>wp_get_attachment_image_attributes</code></li>
<li><code>the_content</code></li>
</ul>
<h4>Adaptive Images</h4>
Also, checkout Adaptive Images for WordPress https://wordpress.org/plugins/adaptive-images/ a self-hosted, transparent mobile images solution.

WURFL Image Tailor (WIT)

Sets up the sources of your images so that they are served via the WURFL Image tailor service (WIT) http://web.wurfl.io/#wit.

WordPress Image shrinker vs WURFL Image Tailor (WIT)