I have over 6 image sizes, Therefore WP cannot satisfy every size with proper cropping as some images get their head cut off and some don't.
Is there a plugin that lets me choose the cropping area of each size (including custom sizes)?
To further explain this, I imagine it'd just let me move the crop selection for every single size.
Is there such solution?
You can customize or change WordPress image sizes using this function: http://codex.wordpress.org/Function_Reference/add_image_size
<?php add_image_size( $name, $width, $height, $crop ); ?>
The $crop parameter can be set to false for proportional or true for hard crop (it will hard crop from the center).
If you use this function on already existing images you will need to regenerate them.
If you want to manually crop individual images you can do this by default in the WordPress image editor, or use a plugin like http://wordpress.org/extend/plugins/tags/crop
If you are not comfortable with the above function you can use a plugin like http://wordpress.org/extend/plugins/simple-image-sizes/
To manually crop each image, click "edit" under the image in the pop-up image editor and you will see this.
To programmatically change the crop area, you will have to use a technique seen in brasofilo comment link.
You can instruct WordPress to always crop some specific sizes of the image to a specific position, for example, the top of the image, so the heads of people not to be cut off in the thumbnail.
There are plugins that allow you to do that manually, for each image, and also plugins that make that automatically for every image you upload, like Image Regenerate & Select Crop. This plugin handles all sort of options for images, and it is super easy to use, the interface is very intuitive and gives you a lot of details and control over the images. Check this out at https://wordpress.org/plugins/image-regenerate-select-crop/
