Stanislav Khromov

This plugin enables upscaling of thumbnails for small media attachments. The default behaviour of WordPress is to not upscale small images, which means 
you are never guaranteed a certain size for a thumbnail format. This plugin corrects that and upscales small images to the specified thumbnail dimensions. 
This is beneficial in grid layouts where images of different sizes can make the grid malfunction.
<a href="https://wordpress.org/plugins/thumbnail-upscale/screenshots/" rel="ugc">Check screenshots for an example!</a>
Important: Your thumbnails format must have the crop setting enabled to be processed by this plugin.
Usage
After you have enabled Thumbnail Upscale plugin, all your future uploaded images will be upscaled. 
For existing images, install and run <a href="https://wordpress.org/plugins/force-regenerate-thumbnails/" rel="ugc">Force Regenerate Thumbnails</a> 
This will upscale your existing media images!
<h3>Requirements</h3>
<ul>
<li>PHP 5.2 or higher strongly recommended</li>
</ul>
<h3>Translations</h3>
None. The plugin has no translateable strings.

Thumbnail Upscale

Whaaaaat? You don't use this plugin? It's good.

It’s still relevant god damn it

Enables upscaling of thumbnails for small media attachments

nosilver4u

Pedro Elsner

Force Regenerate Thumbnails allows you to delete all old images sizes and REALLY regenerate the thumbnails for your uploads.
Regenerate all thumbnails from the Tools admin menu. Regenerate batches of images via the Media Library list mode. Select the images to regenerate and then use the Bulk Actions drop-down menu to Force Regenerate Thumbnails. Use attachment actions to regenerate thumbnails for a single image.
Several filters exist for advanced usage. See more via <a href="https://gist.github.com/nosilver4u/eb858df10521aece2044a3a15ccdd17b" rel="nofollow ugc">this gist</a>.
You may report security issues through our Patchstack Vulnerability Disclosure Program. The Patchstack team helps validate, triage and handle any security vulnerabilities. <a href="https://patchstack.com/database/vdp/force-regenerate-thumbnails" rel="nofollow ugc">Report a security vulnerability.</a>

Force Regenerate Thumbnails

Delete and REALLY force thumbnail regeneration.

Thumbnail Upscale vs Force Regenerate Thumbnails