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.

robertcpalmer

Supercharge your site with instant-loading images (WebP)
Give your website a speed boost in minutes. This plugin converts and compresses your images to the modern, ultra-efficient WebP format—so pages feel snappier and visitors stick around longer.
Why you’ll love it!
Faster pages, happier users: WebP files are smaller, so images load noticeably quicker, but the quality stays sharp. Even when using a Compression Setting of just ‘1’.
Set & forget: Convert and compress everything in your Media Library, then let the plugin automatically optimise new uploads.
No workflow change: In the WordPress admin, you’ll still see images in their original formats. On the front end, however, visitors get the magic: lightweight, crystal-clear WebP files.
Totally FREE! There are no PRO versions to sell or the pushing of unnecessary CDN services, data-limited APIs or any Registration. Use without limits.
Safe rollback: Want to switch back? DEACTIVATE the plugin to serve your original JPG/JPEG/PNG files again — WebP copies are removed as part of the process.
<h4>How it works</h4>
Convert existing images in your Media Library to WebP.
Keep the automatic conversion on for all future uploads.
Enjoy noticeably faster page loads without touching your content.
Pro tips (read me!)
-After converting, flush all caches: any caching plugin (e.g. WP Rocket), server-side cache, and your browser cache (Windows: Ctrl+Shift+R; Mac: ⌘+Shift+R).
-If you deactivate the plugin to revert to originals, flush caches again to ensure changes show everywhere.
-If you upload an image in WebP format, because it will have no fallback jpeg/png file, if you deactivate the plugin, that image will NOT be lost when all WebP files are deleted.
-Important: ALWAYS back up your site before activating or deactivating this plugin.
** Ready to make your images smaller, sharper, and faster? Install now and feel the difference. 🚀
<h3>FAQs</h3>
= If I deactivate the plugin and then reactivate it again, will I need to convert all my images again? = 
Yes. On deactivation of the plugin, it performs a full rollback, and all WebP images created by the plugin will be deleted, and your original files jpg/png will be served. Where you have WebP files that do not have a fallback file, those files will not be removed.
<h4>What Compression Level should I set?</h4>
If your existing images are of reasonable quality, set the Compression Level to ‘1’ and get image compressions of an amazing 90%+ and get excellent performance enhancements on your site, and the quality and sharpness of the images will also amaze.

Images to WebP Converter

Convert and Compress your Image Files into WebP Format. With compression rates up to 90+%.  Make your images and pages load instantly.

Image Quality vs Images to WebP Converter