adamprohack

<h3>What does this plugin do?</h3>
<p>This plugin generate image thumbnails only when site need it, when someone call function with needed size,<br />
and saves disk space when image is uploaded to media library.<br />
You don’t need to use <strong><code>add_image_size()</code></strong> function.</p>
<h3>How it works?</h3>
<ol>
<li>Upload image to media library</li>
<li>Change function <strong><code>wp_get_attachment_image_url()</code></strong> to <strong><code>get_otf_image_url()</code></strong> in your wordpress template</li>
<li>When function is invoke the first time, the image is dynamically adjust, create and stored</li>
<li>Page serve image in need size</li>
</ol>
<h3>Documentation</h3>
<pre><code>`php
function get_otf_image_url(
    $image_id, $size_name, 
    $width = 0, $height = 0, 
    $crop_mode = ["center", "center"], 
    $mime_type = "image/jpeg", $quality = 70)
`
</code></pre>
<p><strong>Parameters</strong></p>
<ul>
<li>Required:<br />
*<strong>$image_id</strong>  – attachment id<br />
***$size_name** – dynamic size name<br />
***$width** – image width<br />
***$height** – image height</li>
<li>Optional<br />
*<strong>$crop_mode</strong> – image crop mode<br />
***$mime_type** – result image mime type<br />
***$quality** – result image quality</li>
</ul>
<p><strong>Return Value</strong></p>
<ul>
<li>Returns an url string</li>
</ul>


WP Images OTF Plugin

Bytes.co

gschoppe

<p>WP SmartCrop allows you to set the ‘focal point’ of any image, right from the media library, then crops your images to match your css rules <em>(no more squished aspect ratios)</em>, keeping that focal point, not only in view, but as near as possible to a ‘rule of thirds’ position in the image.  The results are powerful, composed photos at any screen size, with any constraints.</p>
<ul>
<li>Visually select your images’ focal points with an intuitive click-based interface</li>
<li>Quickly enable or disable smart-cropping on a per-image basis.</li>
<li>Easily target only the images you want to style, with the <em>img.wpsmartcrop-image</em> selector</li>
<li>Automatic image preloader, so your users never see partially loaded images again</li>
<li>Semantic HTML5/CSS3 for modern browsers, with automatic fallback to non-semantic HTML4/CSS2 for older browsers.</li>
<li>Lightweight and fast processing of images, even inside post content</li>
<li>Fully compatible with common caching and optimization plugins and solutions, such as W3 Total Cache, Wordfence, WPEngine’s EverCache, Better WordPress Minify, and Google’s PageSpeed Module.</li>
<li>Lets you take full advantage of the new responsive srcset features added in WordPress 4.4, to make the most of your images.</li>
<li><strong>NEW!</strong> Legacy support for existing cropped thumb sizes allows you to see improvements, right out of the box, without changing your CSS!</li>
</ul>
<h3>Compatibility</h3>
<p>WP SmartCrop has been fully tested in the following browsers:</p>
<ul>
<li>Safari</li>
<li>Chrome</li>
<li>Firefox</li>
<li>Microsoft Edge</li>
</ul>
<p>This is by no means an exhaustive list of supported devices; it just represents our primary target platforms.</p>
<h4>Please Rate/Review and Enjoy</h4>
<p>Your Ratings and Reviews help us to direct our development, and help other users know what to expect.</p>


WP SmartCrop

This function should be a core functionality! So when I found this little gem I was so happy.

A small but significant improvement to WP

WP SmartCrop will crop your images on-the-fly to match your CSS, keeping the main focal point in view.

WP Images OTF Plugin vs WP SmartCrop