Flow Byte

Resizeer is a WordPress plugin designed to help you manage your media library more efficiently, ensuring your images are optimally sized for both web performance and quality. With Resizeer, you can automate the image resizing process, whether you’re uploading new images or dealing with existing ones in your library.

Resizeer

Optimize your images automatically and forget about resizing and compressing them manually before uploading to your WordPress site.

Gagan Deep Singh

Sometimes you may want the images on your blog/site to be pixel perfect, while sometimes you may want them to be compressed to save space on the server.
This plugin allows you to select the quality of the thumbnail images generated by WordPress, as easy as that. Just go to Media Settings page and modify the Image Quality setting.
Plugin only works for new uploads, but in case you want to modify the thumbnails generated earlier, you can either use
<a href="https://wordpress.org/plugins/regenerate-thumbnails/" rel="ugc">Regenerate Thumbnails</a>
or if you are familiar with WP-CLI, then you can use this command to regenerate
<pre><code>wp media regenerate
</code></pre>
P.S. It does not change the quality of the original image that you upload, 
but only changes the quality of the thumbnails WordPress generates from that image.

Image Quality

Lets you adjust the quality of image thumbnails that WordPress generates.

Resizeer vs Image Quality