julioprotzek

For cropping a post thumbnail image to 200×300 pixels:
<pre><code><?php
 the_post();
 img(200, 300);
?>
</code></pre>
This will verify the existence of post thumbnail, crop the image, save it in uploads folder, and generate an image tag.
To verify the existence of a post thumbnail, you can use <code>has_img()</code>
<pre><code><?php if (has_img()): ?>
<figure>
 <?php img(200, 300) ?>
 <figcaption>Some text</figcaption>
</figure>
<?php endif ?>
</code></pre>
To crop images that are not post thumbnails, you can use <code>crop($url, $size)</code>
<pre><code><?php
 $cropped_url= crop( get_bloginfo('url') . '/wp-content/uploads/image.jpg', array(200, 300) );
?>
<img src="<?php echo $cropped_url ?>">
</code></pre>

Image Cropper

Image cropper gives you an API for cropping images inside WordPress.

yaroinfo

Make your images really responsive with Responsive cropped Yummy images, pictures and thumbnails plugin.
Choose focus in the image for every device (mobile, tablet, laptop, desktop) to deliver the best impression to your customers.
Plugin functionality:
<ul>
<li>Choosing a custom position for crop image for each image size;</li>
<li>Adding and cropping a separate image for each image size.</li>
</ul>
We are planning to provide more functionality very soon when we get good rating for current version:
<ul>
<li>Grouping image sizes in images set;</li>
<li>Saving the parameters of previous cropped images for each image size;</li>
<li>Image size filters for different types of posts;</li>
<li>Creating thumbnails of images in accordance with the filter;</li>
<li>Customize responsive breakpoints;</li>
<li>Changing the width and height of the registered dimensions.</li>
</ul>
Email us if you are interested in updates.

Responsive cropped Yummy images, pictures and thumbnails

Manual cropping of images for different sizes

Image Cropper vs Responsive cropped Yummy images, pictures and thumbnails